fix: fix this mess

I am stupid
I am stupid
I am stupid
I can't believe how f- ricking stupid I am

.clang-tidy

@@ -11,6 +11,7 @@ Checks: >
   -bugprone-assignment-in-if-condition,
   -bugprone-easily-swappable-parameters,
   -bugprone-multi-level-implicit-pointer-conversion,
+  -bugprone-unintended-char-ostream-output,
   -readability-function-cognitive-complexity,
   -readability-magic-numbers,
   -readability-redundant-access-specifiers,
@@ -28,7 +29,11 @@ Checks: >
   -cppcoreguidelines-macro-usage,
   -cppcoreguidelines-owning-memory,
   -cppcoreguidelines-non-private-member-variables-in-classes,
-  -cppcoreguidelines-pro-bounds-avoid-unchecked-container-access
+  -cppcoreguidelines-pro-bounds-avoid-unchecked-container-access,
+  -cppcoreguidelines-pro-bounds-array-to-pointer-decay,
+  -cppcoreguidelines-use-enum-class,
+  -bugprone-forward-declaration-namespace,
+  -bugprone-tagged-union-member-count
 
 WarningsAsErrors: "*"
 

CMakeLists.txt

@@ -14,6 +14,7 @@ set(CMAKE_CXX_STANDARD_REQUIRED ON)
 add_subdirectory(furlang)
 add_subdirectory(furvm)
 add_subdirectory(furc)
+add_subdirectory(furas)
 
 if(DOXYGEN_FOUND)
     set(DOXYGEN_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR}/docs)

CONTRIBUTING.md

@@ -1 +1 @@
-TBD
+The commits must be as good as CHatingPython's.

furas/CMakeLists.txt

@@ -0,0 +1,5 @@
+file(GLOB_RECURSE FURAS_SRCS "src/**.cpp")
+file(GLOB_RECURSE FURAS_HDRS "include/**.hpp")
+add_executable(furas ${FURAS_SRCS} ${FURAS_HDRS})
+target_include_directories(furas PUBLIC include/)
+target_link_libraries(furas PRIVATE furlang libfurvm)

furas/examples/array.furas

@@ -0,0 +1,35 @@
+type arr = array $s8 10
+
+func println $arr = native println
+
+public func main = #main
+main:
+    array $arr
+    dup
+    store %0
+
+    lenof
+    store %1
+
+    push $s32 0
+loop:
+    dup
+    load %1
+    ge
+    jnz #end
+body:
+    dup
+    load %0
+    swap
+    push $s8 69
+    set
+
+    push $s32 1
+    add
+
+    jmp #loop
+end:
+    drop
+    load %0
+    call $arr println
+    ret

furas/examples/array2.furas

@@ -0,0 +1,34 @@
+type arr = array $s8 10
+
+func println $arr = native println
+
+public func main = #main
+main:
+    array $arr
+    store %0
+
+    push $s32 2
+    store %1
+
+    push $s32 0
+loop:
+    dup
+    load %1
+    ge
+    jnz #end
+body:
+    dup
+    load %0
+    swap
+    push $s8 69
+    set
+
+    push $s32 1
+    add
+
+    jmp #loop
+end:
+    drop
+    load %0
+    call $arr println
+    ret

furas/examples/ops.furas

@@ -0,0 +1,23 @@
+func println $u32 = native println
+
+public func main = #main
+main:
+    push $u32 0
+    store %0
+loop_header:
+    load %0
+    push $u32 10
+    ge
+    jnz #loop_end
+loop_body:
+    load %0
+    call $u32 println
+
+    load %0
+    push $u32 1
+    add
+    store %0
+
+    jmp #loop_header
+loop_end:
+    ret

furas/include/furas/gen.hpp

@@ -0,0 +1,36 @@
+#ifndef FURAS_GEN_HPP
+#define FURAS_GEN_HPP
+
+#include "furas/lexer.hpp"
+#include "furvm/module.hpp"
+
+#include <string>
+
+namespace furas {
+
+struct generator_error {
+    enum type {
+        Success = 0,
+        Eof     = 1,
+
+        UnexpectedEof    = -1,
+        UnexpectedToken  = -2,
+        UnknownCharacter = -3,
+        UnknownType      = -4,
+    } type = Success;
+    std::string message;
+};
+
+class generator {
+public:
+    struct result {
+        generator_error error;
+        furvm::mod      mod;
+    };
+public:
+    static result generate(lexer lexer);
+};
+
+} // namespace furas
+
+#endif // FURAS_GEN_HPP

furas/include/furas/lexer.hpp

@@ -0,0 +1,47 @@
+#ifndef FURAS_LEXER_HPP
+#define FURAS_LEXER_HPP
+
+#include "furas/token.hpp"
+#include "furlang/result.hpp"
+
+#include <cstddef>
+#include <string_view>
+
+namespace furas {
+
+struct lexer_location {
+    std::string_view filename;
+    std::size_t      row, col;
+};
+
+struct lexer_error {
+    enum type {
+        EndOfFile = 0,
+        UnknownCharacter,
+    } type;
+
+    lexer_location location;
+    std::string    message;
+};
+
+using token_r = furlang::result<token, lexer_error>;
+
+class lexer {
+public:
+    lexer(std::string_view filename, std::string_view content)
+      : m_filename(filename), m_content(content) {}
+
+    token_r next_token();
+private:
+    constexpr lexer_location location() const { return { m_filename, m_cursor - m_lineStart, m_column }; }
+private:
+    std::string_view m_filename;
+    std::string_view m_content;
+    std::size_t      m_cursor    = 0;
+    std::size_t      m_lineStart = 0;
+    std::size_t      m_column    = 0;
+};
+
+} // namespace furas
+
+#endif // FURAS_LEXER_HPP

furas/include/furas/token.hpp

@@ -0,0 +1,94 @@
+#ifndef FURAS_TOKEN_HPP
+#define FURAS_TOKEN_HPP
+
+#include <cstdint>
+#include <string_view>
+
+namespace furas {
+
+struct token {
+    enum type {
+        Identifier = 0, /**< An identifier. */
+        Signed,         /**< A signed integer. */
+        Unsigned,       /**< An unsigned integer. */
+
+        // Markers
+        Monkey,  /**< Constant marker (`@`). */
+        Dolar,   /**< Type marker(`$`). */
+        Sha256,  /**< Label marker(`#`). */
+        Percent, /**< Variable marker(`%`). The more the better. */
+
+        EqSign, /**< `=` */
+        Dot,    /**< . */
+        Colon,  /**< `:` */
+
+        // Keywords
+        Func,    /**< `func` keyword for defining functions. */
+        Type,    /**< `type` keyword for defining types. */
+        Native,  /**< `native` keyword for native functions. :v: */
+        Import,  /**< `import` keyword for importing functions and types. */
+        Public,  /**< `public` access specifier. */
+        Private, /**< `private` access specifier. */
+
+        // Instructions
+        Push,
+        Array,
+        Get,
+        Set,
+        Drop,
+        Dup,
+        Swap,
+        Clone,
+        Ref,
+        Add,
+        Sub,
+        Mul,
+        Div,
+        Mod,
+        Eq,
+        Neq,
+        Lt,
+        Gt,
+        Le,
+        Ge,
+        Ptrof,
+        Sizeof,
+        Lenof,
+        Load,
+        Store,
+        Call,
+        Jmp,
+        Jnz,
+        Ret,
+
+        Count
+    } type = Count;
+    union value {
+        std::nullptr_t   null = nullptr;
+        std::string_view string;
+        std::int64_t     integer;
+        std::uint64_t    uint;
+    } value;
+
+    token(enum type type)
+      : type(type) {}
+
+    token(enum type type, std::string_view string)
+      : type(type) {
+        value.string = string;
+    }
+
+    token(std::uint64_t num)
+      : type(Unsigned) {
+        value.uint = num;
+    }
+
+    token(std::int64_t num)
+      : type(Signed) {
+        value.integer = num;
+    }
+};
+
+} // namespace furas
+
+#endif // FURAS_TOKEN_HPP

furas/src/gen.cpp

@@ -0,0 +1,558 @@
+#include "furas/gen.hpp"
+
+#include "furas/token.hpp"
+#include "furvm/function.hpp"
+#include "furvm/fwd.hpp"
+#include "furvm/instruction.hpp"
+
+#include <cassert>
+#include <cstdint>
+#include <cstdlib>
+#include <limits>
+#include <optional>
+#include <stdexcept>
+#include <unordered_map>
+#include <utility>
+#include <vector>
+
+namespace furas {
+
+using namespace std::string_literals;
+
+namespace {
+
+struct instruction {
+    furvm::instruction_t fur{};
+    enum arg_type {
+        None = 0,
+        Type,
+        Constant,
+        Variable,
+        Function,
+        Label,
+    } arg = None;
+};
+
+// NOLINTBEGIN
+std::unordered_map<enum token::type, instruction> instructions = {
+    { token::Array, { furvm::instruction_t::Array, instruction::Type } },
+    { token::Get, { furvm::instruction_t::Get } },
+    { token::Set, { furvm::instruction_t::Set } },
+    { token::Drop, { furvm::instruction_t::Drop } },
+    { token::Dup, { furvm::instruction_t::Duplicate } },
+    { token::Swap, { furvm::instruction_t::Swap } },
+    { token::Clone, { furvm::instruction_t::Clone } },
+    { token::Ref, { furvm::instruction_t::Reference } },
+    { token::Add, { furvm::instruction_t::Add } },
+    { token::Sub, { furvm::instruction_t::Sub } },
+    { token::Mul, { furvm::instruction_t::Mul } },
+    { token::Div, { furvm::instruction_t::Div } },
+    { token::Mod, { furvm::instruction_t::Mod } },
+    { token::Eq, { furvm::instruction_t::Equals } },
+    { token::Neq, { furvm::instruction_t::NotEquals } },
+    { token::Lt, { furvm::instruction_t::LessThan } },
+    { token::Gt, { furvm::instruction_t::GreaterThan } },
+    { token::Le, { furvm::instruction_t::LessEqual } },
+    { token::Ge, { furvm::instruction_t::GreaterEqual } },
+    { token::Ptrof, { furvm::instruction_t::Pointerof } },
+    { token::Sizeof, { furvm::instruction_t::Sizeof } },
+    { token::Lenof, { furvm::instruction_t::Lengthof } },
+    { token::Load, { furvm::instruction_t::Load, instruction::Variable } },
+    { token::Store, { furvm::instruction_t::Store, instruction::Variable } },
+    { token::Call, { furvm::instruction_t::Call, instruction::Function } },
+    { token::Jmp, { furvm::instruction_t::Jump, instruction::Label } },
+    { token::Jnz, { furvm::instruction_t::JumpNotZero, instruction::Label } },
+    { token::Ret, { furvm::instruction_t::Return } },
+};
+// NOLINTEND
+
+const char* token_type(enum token::type type) {
+    switch (type) {
+    case token::Identifier: return "identifier";
+    case token::Signed: return "signed";
+    case token::Unsigned: return "unsigned";
+    case token::Monkey: return "'@'";
+    case token::Dolar: return "'$'";
+    case token::Sha256: return "'#'";
+    case token::Percent: return "'%'";
+    case token::EqSign: return "'='";
+    case token::Dot: return "'.'";
+    case token::Colon: return "':'";
+    case token::Func: return "func";
+    case token::Type: return "type";
+    case token::Native: return "native";
+    case token::Import: return "import";
+    case token::Public: return "public";
+    case token::Private: return "private";
+    case token::Push: return "push";
+    case token::Array: return "array";
+    case token::Get: return "get";
+    case token::Set: return "set";
+    case token::Drop: return "drop";
+    case token::Dup: return "dup";
+    case token::Swap: return "swap";
+    case token::Clone: return "clone";
+    case token::Ref: return "ref";
+    case token::Add: return "add";
+    case token::Sub: return "sub";
+    case token::Mul: return "mul";
+    case token::Div: return "div";
+    case token::Mod: return "mod";
+    case token::Eq: return "eq";
+    case token::Neq: return "neq";
+    case token::Lt: return "lt";
+    case token::Gt: return "gt";
+    case token::Le: return "le";
+    case token::Ge: return "ge";
+    case token::Ptrof: return "ptrof";
+    case token::Sizeof: return "sizeof";
+    case token::Lenof: return "lenof";
+    case token::Load: return "load";
+    case token::Store: return "store";
+    case token::Call: return "call";
+    case token::Jmp: return "jmp";
+    case token::Jnz: return "jnz";
+    case token::Ret: return "ret";
+    case token::Count: break;
+    }
+    throw std::runtime_error("unreachable");
+}
+
+struct mod_context {
+    struct label_context {
+        struct function_info {
+            std::string         name;
+            furvm::function_sig signature;
+            bool                pub;
+        };
+
+        static constexpr std::size_t INVALID = std::numeric_limits<std::size_t>::max();
+
+        std::size_t                offset = INVALID;
+        std::vector<function_info> functions;
+        std::vector<std::size_t>   unknowns;
+    };
+
+    furvm::mod mod;
+    std::unordered_map<std::pair<std::string, furvm::function_sig>,
+        furvm::function_h,
+        furlang::utility::
+            pair_hash<std::string, furvm::function_sig, std::hash<std::string>, furvm::detail::function_sig_hash>>
+                                                       functions;
+    std::unordered_map<std::string, furvm::mod_type_h> types;
+
+    std::unordered_map<std::string, label_context> labels;
+
+    struct token_result {
+        generator_error error;
+        token           token;
+
+        struct token* operator->() { return &token; }
+        struct token& operator*() { return token; }
+
+        bool operator!() const { return error.type != generator_error::Success; }
+    };
+
+    mod_context() {
+        types.emplace("s8", mod.emplace_type(furvm::mod_type::S8));
+        types.emplace("u8", mod.emplace_type(furvm::mod_type::U8));
+        types.emplace("s16", mod.emplace_type(furvm::mod_type::S16));
+        types.emplace("u16", mod.emplace_type(furvm::mod_type::U16));
+        types.emplace("s32", mod.emplace_type(furvm::mod_type::S32));
+        types.emplace("u32", mod.emplace_type(furvm::mod_type::U32));
+        types.emplace("s64", mod.emplace_type(furvm::mod_type::S64));
+        types.emplace("u64", mod.emplace_type(furvm::mod_type::U64));
+    }
+
+    static token_result next_token(lexer& lexer) {
+        auto token = lexer.next_token();
+        if (token.has_error()) {
+            switch (token.error().type) {
+            case lexer_error::EndOfFile:
+                return { { generator_error::UnexpectedEof, "Unexpected end of file" }, { token::Count } };
+            case lexer_error::UnknownCharacter:
+                return { { generator_error::UnknownCharacter, token.error().message }, { token::Count } };
+            }
+        }
+        return { { generator_error::Success }, *token };
+    }
+
+    static token_result eat_token(lexer& lexer, enum token::type type) {
+        auto token = next_token(lexer);
+        if (!token) return token;
+        if (token.token.type != type) {
+            return { { generator_error::UnexpectedToken,
+                         "Expected "s + token_type(type) + ", but got " + token_type(token->type) },
+                { token::Count } };
+        }
+        return { { generator_error::Success }, token.token };
+    }
+
+    generator_error generate(lexer& lexer) {
+        auto result = next_token(lexer);
+        if (result.error.type == generator_error::UnexpectedEof) return { generator_error::Eof };
+        if (!result) return result.error;
+        switch (result->type) {
+        case token::Identifier: {
+            std::string labelName = std::string(result->value.string);
+
+            result = eat_token(lexer, token::Colon);
+            if (!result) return result.error;
+
+            auto& label = labels[labelName];
+            if (label.offset != label_context::INVALID)
+                return { generator_error::UnexpectedToken, "Label "s + labelName + " already exists" };
+            label.offset = mod.bytecode().size();
+
+            for (auto& func : label.functions) {
+                furvm::function_h handle =
+                    (func.pub ? mod.emplace_function(func.name, std::move(func.signature), label.offset)
+                              : mod.emplace_function(std::move(func.signature), label.offset));
+
+                functions.emplace(std::make_pair(std::move(func.name), std::move(func.signature)), handle);
+
+                handle.dispatch();
+            }
+            for (auto unknown : label.unknowns) {
+                std::ptrdiff_t jmpOff = static_cast<std::ptrdiff_t>(label.offset - unknown);
+                if (jmpOff < std::numeric_limits<std::int8_t>::min() ||
+                    jmpOff > std::numeric_limits<std::int8_t>::max()) {
+                    assert(false); // TODO: Further jumps are not implemented
+                }
+                mod.bytecode()[unknown - 1] = jmpOff;
+            }
+            label.functions = {};
+            label.unknowns  = {};
+            return { generator_error::Success };
+        }
+
+        case token::Func:
+        case token::Type:
+        case token::Public:
+        case token::Private: {
+            bool pub = false;
+            if (result->type == token::Public) {
+                pub    = true;
+                result = next_token(lexer);
+                if (!result) return { result.error };
+            } else if (result->type == token::Private) {
+                result = next_token(lexer);
+                if (!result) return { result.error };
+            }
+
+            if (result->type == token::Func) {
+                auto nameRes = next_token(lexer);
+                if (!nameRes) return nameRes.error;
+
+                furvm::function_sig signature;
+
+                result = next_token(lexer);
+                if (!result) return result.error;
+                while (result->type == token::Dolar) {
+                    result = eat_token(lexer, token::Identifier);
+                    if (!result) return result.error;
+                    if (auto it = types.find(std::string(result->value.string)); it != types.end()) {
+                        signature.params.push_back(it->second);
+                    } else {
+                        return { generator_error::UnknownType, "Unknown type "s + std::string(result->value.string) };
+                    }
+
+                    result = next_token(lexer);
+                    if (!result) return result.error;
+                }
+                if (result->type != token::EqSign) return result.error;
+
+                result = next_token(lexer);
+                if (!result) return result.error;
+                if (result->type == token::Dolar) {
+                    result = eat_token(lexer, token::Identifier);
+                    if (!result) return result.error;
+                    if (auto it = types.find(std::string(result->value.string)); it != types.end()) {
+                        signature.returnType = it->second;
+                    } else {
+                        return { generator_error::UnknownType, "Unknown type "s + std::string(result->value.string) };
+                    }
+
+                    result = next_token(lexer);
+                    if (!result) return result.error;
+                }
+
+                switch (result->type) {
+                case token::Sha256: {
+                    result = eat_token(lexer, token::Identifier);
+                    if (!result) return result.error;
+
+                    std::string name = std::string(nameRes->value.string);
+
+                    std::string labelName = std::string(result->value.string);
+                    std::size_t offset    = 0;
+                    if (auto it = labels.find(labelName); it != labels.end()) {
+                        offset = it->second.offset;
+                    } else {
+                        labels[labelName].functions.emplace_back(
+                            label_context::function_info{ std::move(name), std::move(signature), pub });
+                        return { generator_error::Success };
+                    }
+
+                    furvm::function_h handle =
+                        (pub ? mod.emplace_function(name, signature, offset) : mod.emplace_function(signature, offset));
+
+                    functions.emplace(std::make_pair(name, std::move(signature)), handle);
+
+                    handle.dispatch();
+                    return { generator_error::Success };
+                }
+                case token::Native: {
+                    result = eat_token(lexer, token::Identifier);
+                    if (!result) return result.error;
+
+                    std::string nativeName = std::string(result->value.string);
+
+                    std::string name = std::string(nameRes->value.string);
+
+                    furvm::function_h handle = (pub ? mod.emplace_function(name, signature, std::move(nativeName))
+                                                    : mod.emplace_function(signature, std::move(nativeName)));
+
+                    functions.emplace(std::make_pair(name, std::move(signature)), handle);
+
+                    handle.dispatch();
+                    return { generator_error::Success };
+                }
+                case token::Import: {
+                    throw std::runtime_error("unimplemented");
+                }
+                default:
+                    return { generator_error::UnexpectedToken,
+                        "Unexpected token "s + token_type(result->type) +
+                            ", expected label name, `native`, or `import`" };
+                }
+            }
+
+            if (result->type == token::Type) {
+                auto nameRes = eat_token(lexer, token::Identifier);
+                if (!nameRes) return nameRes.error;
+
+                result = eat_token(lexer, token::EqSign);
+                if (!result) return result.error;
+
+                result = next_token(lexer);
+                if (!result) return result.error;
+                switch (result->type) {
+                case token::Import: {
+                    auto typeNameRes = eat_token(lexer, token::Identifier);
+                    if (!typeNameRes) return typeNameRes.error;
+                    return { generator_error::Success };
+                }
+                case token::Array: {
+                    result = eat_token(lexer, token::Dolar);
+                    if (!result) return result.error;
+
+                    auto typeNameRes = eat_token(lexer, token::Identifier);
+                    if (!typeNameRes) return typeNameRes.error;
+
+                    auto size = eat_token(lexer, token::Unsigned);
+                    if (!size) return size.error;
+
+                    furvm::mod_type_id innerId = 0;
+                    if (auto it = types.find(std::string(typeNameRes->value.string)); it != types.end()) {
+                        innerId = it->second.id();
+                    } else {
+                        return { generator_error::UnknownType,
+                            "Unknown type "s + std::string(typeNameRes->value.string) };
+                    }
+
+                    auto type = mod.emplace_type(innerId, size->value.uint);
+                    types.emplace(std::string(nameRes->value.string), type);
+                    type.dispatch();
+
+                    return { generator_error::Success };
+                }
+                default:
+                    return { generator_error::UnexpectedToken,
+                        "Unexpected token "s + token_type(result->type) +
+                            ", expected either type, `import`, or `array`" };
+                }
+            }
+
+            return { generator_error::UnexpectedToken,
+                "Unexpected token "s + token_type(result->type) + ", expected either `func` or `type`" };
+        }
+
+        case token::Push: {
+            auto result = eat_token(lexer, token::Dolar);
+            if (!result) return result.error;
+            auto typeName = eat_token(lexer, token::Identifier);
+            if (!typeName) return result.error;
+            auto it = types.find(std::string(typeName->value.string));
+            if (it == types.end())
+                return { generator_error::UnexpectedToken, "Unknown type "s + std::string(typeName->value.string) };
+            // TODO: Add support for signed integers
+            auto value = eat_token(lexer, token::Unsigned);
+            if (!value) return result.error;
+            auto type = it->second;
+            switch (type->type) {
+            case furvm::mod_type::S8: {
+                mod.bytecode().push_back(static_cast<furvm::byte>(furvm::instruction_t::PushS8));
+                mod.bytecode().push_back(value->value.uint & 0xFF);
+            } break;
+            case furvm::mod_type::U8: {
+                mod.bytecode().push_back(static_cast<furvm::byte>(furvm::instruction_t::PushU8));
+                mod.bytecode().push_back(value->value.uint & 0xFF);
+            } break;
+            case furvm::mod_type::S16: {
+                mod.bytecode().push_back(static_cast<furvm::byte>(furvm::instruction_t::PushS16));
+                mod.bytecode().push_back(value->value.uint & 0xFF);
+                mod.bytecode().push_back((value->value.uint >> 8) & 0xFF);
+            } break;
+            case furvm::mod_type::U16: {
+                mod.bytecode().push_back(static_cast<furvm::byte>(furvm::instruction_t::PushU16));
+                mod.bytecode().push_back(value->value.uint & 0xFF);
+                mod.bytecode().push_back((value->value.uint >> 8) & 0xFF);
+            } break;
+            case furvm::mod_type::S32: {
+                mod.bytecode().push_back(static_cast<furvm::byte>(furvm::instruction_t::PushS32));
+                mod.bytecode().push_back(value->value.uint & 0xFF);
+            } break;
+            case furvm::mod_type::U32: {
+                mod.bytecode().push_back(static_cast<furvm::byte>(furvm::instruction_t::PushU32));
+                mod.bytecode().push_back(value->value.uint & 0xFF);
+            } break;
+            default:
+                return { generator_error::UnexpectedToken, "Unexpected type "s + std::string(typeName->value.string) };
+            }
+            return { generator_error::Success };
+        }
+
+        case token::Array:
+        case token::Get:
+        case token::Set:
+        case token::Drop:
+        case token::Dup:
+        case token::Swap:
+        case token::Clone:
+        case token::Ref:
+        case token::Add:
+        case token::Sub:
+        case token::Mul:
+        case token::Div:
+        case token::Mod:
+        case token::Eq:
+        case token::Neq:
+        case token::Lt:
+        case token::Gt:
+        case token::Le:
+        case token::Ge:
+        case token::Ptrof:
+        case token::Sizeof:
+        case token::Lenof:
+        case token::Load:
+        case token::Store:
+        case token::Call:
+        case token::Jmp:
+        case token::Jnz:
+        case token::Ret: {
+            auto it = instructions.find(result->type);
+            assert(it != instructions.end());
+            mod.bytecode().push_back(static_cast<furvm::byte>(it->second.fur));
+            switch (it->second.arg) {
+            case instruction::None: break;
+            case instruction::Type: {
+                result = eat_token(lexer, token::Dolar);
+                if (!result) return result.error;
+                result = eat_token(lexer, token::Identifier);
+                if (!result) return result.error;
+                auto type = types.find(std::string(result->value.string));
+                if (type == types.end())
+                    return { generator_error::UnknownType, "Unknown type "s + std::string(result->value.string) };
+                auto id = type->second.id();
+                mod.bytecode().push_back((id >> 0) & 0xFF);
+                mod.bytecode().push_back((id >> 8) & 0xFF);
+                mod.bytecode().push_back((id >> 16) & 0xFF);
+                mod.bytecode().push_back((id >> 24) & 0xFF);
+            } break;
+            case instruction::Constant: {
+                assert(false); // TODO: Unimplemented
+            } break;
+            case instruction::Variable: {
+                result = eat_token(lexer, token::Percent);
+                if (!result) return result.error;
+                result = eat_token(lexer, token::Unsigned);
+                if (!result) return result.error;
+                std::uint16_t var = result->value.uint;
+                mod.bytecode().push_back((var >> 0) & 0xFF);
+                mod.bytecode().push_back((var >> 8) & 0xFF);
+            } break;
+            case instruction::Function: {
+                furvm::function_sig signature;
+                while ((result = next_token(lexer)).error.type == generator_error::Success &&
+                       result->type == token::Dolar) {
+                    result = eat_token(lexer, token::Identifier);
+                    if (!result) return result.error;
+                    auto type = types.find(std::string(result->value.string));
+                    if (type == types.end())
+                        return { generator_error::UnknownType, "Unknown type "s + std::string(result->value.string) };
+                    signature.params.push_back(type->second);
+                }
+                if (!result || result->type != token::Identifier) return result.error;
+                std::string name(result->value.string);
+
+                auto func = functions.find(std::make_pair(name, signature));
+                if (func == functions.end())
+                    return { generator_error::UnknownType, "Unknown type "s + std::string(result->value.string) };
+                auto id = func->second.id();
+                mod.bytecode().push_back((id >> 0) & 0xFF);
+                mod.bytecode().push_back((id >> 8) & 0xFF);
+            } break;
+            case instruction::Label: {
+                result = eat_token(lexer, token::Sha256);
+                if (!result) return result.error;
+                result = eat_token(lexer, token::Identifier);
+                if (!result) return result.error;
+                auto& label  = labels[std::string(result->value.string)];
+                auto  offset = label.offset;
+                if (offset == label_context::INVALID) {
+                    label.unknowns.push_back(mod.bytecode().size() + 1);
+                    mod.bytecode().push_back(0);
+                    return { generator_error::Success };
+                }
+                std::ptrdiff_t jmpOff = static_cast<std::ptrdiff_t>(offset - mod.bytecode().size() - 1);
+                if (jmpOff < std::numeric_limits<std::int8_t>::min() ||
+                    jmpOff > std::numeric_limits<std::int8_t>::max()) {
+                    assert(false); // TODO: Further jumps are not implemented
+                }
+                mod.bytecode().push_back(jmpOff);
+            } break;
+            }
+            return { generator_error::Success };
+        }
+
+        case token::Signed:
+        case token::Unsigned:
+        case token::Colon:
+        case token::Monkey:
+        case token::Dolar:
+        case token::Sha256:
+        case token::Percent:
+        case token::EqSign:
+        case token::Dot:
+        case token::Native:
+        case token::Import:
+        case token::Count: break;
+        }
+        return { generator_error::UnexpectedToken, "Unexpected token "s + token_type(result->type) };
+    }
+};
+
+} // namespace
+
+generator::result generator::generate(lexer lexer) {
+    mod_context     context;
+    generator_error error;
+    do {
+        error = context.generate(lexer);
+    } while (error.type == generator_error::Success);
+    if (error.type == generator_error::Eof) return { { generator_error::Success }, std::move(context.mod) };
+    return { error };
+}
+
+} // namespace furas

furas/src/lexer.cpp

@@ -0,0 +1,98 @@
+#include "furas/lexer.hpp"
+
+#include <cctype>
+#include <unordered_map>
+
+namespace furas {
+
+using namespace std::string_literals;
+
+token_r lexer::next_token() {
+    while (m_cursor < m_content.size() && std::isspace(m_content[m_cursor]) != 0) {
+        if (m_content[m_cursor] == '\n') {
+            m_lineStart = m_cursor + 1;
+            ++m_column;
+        }
+        ++m_cursor;
+    }
+
+    // TODO: Add support for single-line comments
+    // TODO: Add support for multi-line comments
+
+    if (m_cursor >= m_content.size()) return token_r{ lexer_error{ lexer_error::EndOfFile, location() } };
+
+    // TODO: Add support for negative integers (I am positive thanks to stasiu :v:)
+    // TODO: Add support for hexadecimal and binary numeric literals
+    if (std::isdigit(m_content[m_cursor]) != 0) {
+        std::uint64_t num = 0;
+        while (m_cursor < m_content.size() && std::isdigit(m_content[m_cursor]) != 0) {
+            num *= 10;
+            num += m_content[m_cursor++] - '0';
+        }
+        return { num };
+    }
+
+    static std::unordered_map<std::string_view, enum token::type> s_tokens = {
+        { "func", token::Func },
+        { "type", token::Type },
+        { "native", token::Native },
+        { "import", token::Import },
+        { "public", token::Public },
+        { "private", token::Private },
+
+        { "push", token::Push },
+        { "array", token::Array },
+        { "get", token::Get },
+        { "set", token::Set },
+        { "drop", token::Drop },
+        { "dup", token::Dup },
+        { "swap", token::Swap },
+        { "clone", token::Clone },
+        { "ref", token::Ref },
+        { "add", token::Add },
+        { "sub", token::Sub },
+        { "mul", token::Mul },
+        { "div", token::Div },
+        { "mod", token::Mod },
+        { "eq", token::Eq },
+        { "neq", token::Neq },
+        { "lt", token::Lt },
+        { "gt", token::Gt },
+        { "le", token::Le },
+        { "ge", token::Ge },
+        { "ptrof", token::Ptrof },
+        { "sizeof", token::Sizeof },
+        { "lenof", token::Lenof },
+        { "load", token::Load },
+        { "store", token::Store },
+        { "call", token::Call },
+        { "jmp", token::Jmp },
+        { "jnz", token::Jnz },
+        { "ret", token::Ret },
+    };
+
+    if (std::isalnum(m_content[m_cursor]) != 0) {
+        std::size_t begin = m_cursor++;
+        while (m_cursor < m_content.size() && (std::isalnum(m_content[m_cursor]) != 0 || m_content[m_cursor] == '_'))
+            ++m_cursor;
+        std::string_view str = m_content.substr(begin, m_cursor - begin);
+        if (auto it = s_tokens.find(str); it != s_tokens.end()) return { it->second };
+        return { token::Identifier, str };
+    }
+
+    switch (m_content[m_cursor]) {
+    case '@': ++m_cursor; return { token::Monkey };
+    case '$': ++m_cursor; return { token::Dolar };
+    case '#': ++m_cursor; return { token::Sha256 };
+    case '%': ++m_cursor; return { token::Percent };
+    case '=': ++m_cursor; return { token::EqSign };
+    case '.': ++m_cursor; return { token::Dot };
+    case ':': ++m_cursor; return { token::Colon };
+    default:
+        return token_r{
+            lexer_error{ lexer_error::UnknownCharacter, location(), "Unknown character '"s + m_content[m_cursor] + "'" }
+        };
+    }
+}
+
+} // namespace furas

furas/src/main.cpp

@@ -0,0 +1,39 @@
+#include "furas/gen.hpp"
+#include "furas/lexer.hpp"
+
+#include <fstream>
+#include <furvm/module.hpp>
+#include <iostream>
+
+int main(int argc, char** argv) { // NOLINT
+    if (argc < 2) {
+        std::cerr << "feed me more arguments daddy >_<\n";
+        return 1;
+    }
+    if (argc > 2) {
+        std::cerr << "too much O_O\n";
+        return 1;
+    }
+
+    const char* filepath = argv[1];
+
+    std::ifstream file(filepath, std::ios::binary | std::ios::ate | std::ios::in);
+    if (!file.is_open()) {
+        std::cerr << "file won't open >~<\n";
+        return 1;
+    }
+    std::string content;
+    content.resize(file.tellg());
+    file.seekg(0);
+    file.read(content.data(), static_cast<std::streamsize>(content.size()));
+
+    auto result = furas::generator::generate(furas::lexer(filepath, content));
+    if (result.error.type != furas::generator_error::Success) {
+        std::cerr << result.error.message << '\n';
+        return 1;
+    }
+
+    result.mod.serialize(std::cout);
+
+    return 0;
+}

furc/CMakeLists.txt

@@ -4,7 +4,7 @@ add_library(libfurc ${FURC_SRCS} ${FURC_HDRS})
 target_include_directories(libfurc PUBLIC include/)
 target_compile_definitions(libfurc PRIVATE LIBFURC)
 set_target_properties(libfurc PROPERTIES PREFIX "")
-target_link_libraries(libfurc PUBLIC furlang)
+target_link_libraries(libfurc PUBLIC furlang libfurvm)
 add_executable(furc src/main.cpp)
 target_link_libraries(furc PRIVATE libfurc)
 

furc/include/furc/ast/declaration.hpp

@@ -4,11 +4,38 @@
 #include "furc/ast/node.hpp"
 #include "furc/ast/statement.hpp"
 
+#include <optional>
 #include <string>
+#include <type_traits>
+#include <vector>
 
 namespace furc {
 namespace ast {
 
+/**
+ * @brief Type class for AST declarations.
+ */
+class type {
+public:
+    template <typename NameFwd, typename = std::enable_if_t<std::is_constructible_v<std::string, NameFwd>>>
+    type(NameFwd&& name)
+      : m_name(std::forward<NameFwd>(name)) {}
+public:
+    const std::string& name() const { return m_name; }
+private:
+    std::string m_name;
+};
+
+enum class declaration_access_t {
+    Implicit = 0, /**< Implicit access. */
+    Public,       /**< Public access. */
+    Private,      /**< Private access. */
+};
+
+static inline bool same_access(declaration_access_t lhs, declaration_access_t rhs) {
+    return lhs == declaration_access_t::Implicit || lhs == rhs;
+}
+
 /**
  * @brief Declaration node type.
  */
@@ -26,9 +53,10 @@ public:
      * @brief Construct a new declaration AST node.
      *
      * @param location Node location.
+     * @param access Declaration access.
      */
-    declaration_node(struct location location)
-      : abstract_node(location) {}
+    declaration_node(struct location location, declaration_access_t access)
+      : abstract_node(location), p_access(access) {}
 public:
     /**
      * @brief Returns this node's category.
@@ -50,8 +78,31 @@ public:
      * @return The declaration type.
      */
     virtual declaration_node_t declaration_type() const = 0;
+
+    /**
+     * @brief Returns the declaration's access.
+     *
+     * @return Access.
+     */
+    declaration_access_t access() const { return p_access; }
 protected:
     bool equal(const node& rhs) const override;
+protected:
+    declaration_access_t p_access;
+};
+
+/**
+ * @brief Parameter of function declaration AST node.
+ */
+struct function_declaration_param {
+    std::string name;
+    type        type;
+};
+
+enum class function_declaration_node_t {
+    Normal = 0,
+    Import,
+    Native,
 };
 
 /**
@@ -64,10 +115,20 @@ public:
      *
      * @param location Node location.
      * @param name Name of the function.
+     * @param type Return type of the function.
      */
-    template <typename T>
-    function_declaration_node(struct location location, T&& name)
-      : declaration_node(location), p_name(std::forward<T>(name)) {}
+    template <typename T, typename ParamsFwd>
+    function_declaration_node(struct location location,
+        declaration_access_t                  access,
+        T&&                                   name,
+        std::optional<type>&&                 returnType,
+        ParamsFwd&&                           params,
+        function_declaration_node_t           type = function_declaration_node_t::Normal)
+      : declaration_node(location, access),
+        p_name(std::forward<T>(name)),
+        p_returnType(std::move(returnType)),
+        p_params(std::forward<ParamsFwd>(params)),
+        p_type(type) {}
 public:
     /**
      * @brief Returns this node's declaration type.
@@ -82,6 +143,27 @@ public:
      * @return Name of the function.
      */
     std::string name() const { return p_name; }
+
+    /**
+     * @brief Returns function's return type.
+     *
+     * @return Function's return type.
+     */
+    const std::optional<type>& return_type() const { return p_returnType; }
+
+    /**
+     * @brief Returns function's parameters.
+     *
+     * @return Function's parameters.
+     */
+    const std::vector<function_declaration_param>& params() const { return p_params; }
+
+    /**
+     * @brief Returns function's type.
+     *
+     * @return Function's type.
+     */
+    function_declaration_node_t type() const { return p_type; }
 public:
     void accept(visitor& visitor) const override;
 
@@ -93,6 +175,21 @@ protected:
      * @brief Name of the function.
      */
     std::string p_name;
+
+    /**
+     * @brief Return type of the function.
+     */
+    std::optional<class type> p_returnType;
+
+    /**
+     * @brief Parameters of the function.
+     */
+    std::vector<function_declaration_param> p_params;
+
+    /**
+     * @brief Type of the function declaration.
+     */
+    function_declaration_node_t p_type;
 };
 
 /**
@@ -105,11 +202,22 @@ public:
      *
      * @param location Node location.
      * @param name Name of the function.
+     * @param type Return type of the function.
      * @param body Body of the function.
      */
-    template <typename T>
-    function_definition_node(struct location location, T&& name, body&& body)
-      : function_declaration_node(location, std::forward<T>(name)), m_body(std::move(body)) {}
+    template <typename T, typename ParamsFwd>
+    function_definition_node(struct location location,
+        declaration_access_t                 access,
+        T&&                                  name,
+        std::optional<class type>&&          type,
+        ParamsFwd&&                          params,
+        body&&                               body)
+      : function_declaration_node(location,
+            access,
+            std::forward<T>(name),
+            std::move(type),
+            std::forward<ParamsFwd>(params)),
+        m_body(std::move(body)) {}
 public:
     /**
      * @brief Returns this node's declaration type.

furc/include/furc/ast/expression.hpp

@@ -4,6 +4,8 @@
 #include "furc/ast/node.hpp"
 #include "furc/ast/statement.hpp"
 
+#include <vector>
+
 namespace furc {
 namespace ast {
 
@@ -16,6 +18,7 @@ enum class expression_node_t {
     Unaryop,   /**< Unary operation expression */
     Binop,     /**< Binary operation expression */
     VarAssign, /**< Variable assignment expression */
+    FuncCall,  /**< Function call expression. */
 };
 
 /**
@@ -110,6 +113,8 @@ enum class unaryop_expression_node_t {
     PostfixIncrement, /**< Postfix increment */
     PrefixDecrement,  /**< Prefix decrement */
     PostfixDecrement, /**< Postfix decrement */
+    Pointerof,        /**< Pointerof */
+    Sizeof,           /**< Sizeof */
 };
 
 /**
@@ -350,6 +355,54 @@ private:
     expression_node_p       m_rhs;
 };
 
+/**
+ * @brief Function call expression AST node.
+ */
+class function_call_expression_node final : public expression_node {
+public:
+    /**
+     * @brief Construct a new function call expression AST node.
+     *
+     * @param location Node location.
+     * @param func Left-hand-side expression.
+     * @param args Function arguments.
+     */
+    function_call_expression_node(struct location location,
+        expression_node_p&&                       func,
+        std::vector<expression_node_p>&&          args)
+      : expression_node(location), m_func(std::move(func)), m_args(std::move(args)) {}
+
+    /**
+     * @brief Returns this node's left-hand-side expression.
+     *
+     * @return The left-hand-side expression.
+     */
+    const expression_node_p& func() const { return m_func; }
+
+    /**
+     * @brief Returns this node's argument expressions.
+     *
+     * @return The argument expressions.
+     */
+    const std::vector<expression_node_p>& args() const { return m_args; }
+public:
+    /**
+     * @brief Returns this node's expression type.
+     *
+     * @return expression_node_t::FuncCall.
+     */
+    expression_node_t expression_type() const override { return expression_node_t::FuncCall; }
+public:
+    void accept(visitor& visitor) const override;
+
+    std::ostream& print(std::ostream& os) const override;
+protected:
+    bool equal(const node& rhs) const override;
+private:
+    expression_node_p              m_func;
+    std::vector<expression_node_p> m_args;
+};
+
 } // namespace ast
 } // namespace furc
 

furc/include/furc/ast/fwd.hpp

@@ -71,6 +71,10 @@ using expression_node_p = node_p<expression_node>; /**< Alias for a shared point
 
 using expression_node_r = node_r<expression_node>; /**< Alias for expression_node result */
 
+class type;
+
+using type_r = furlang::result<type, error>; /**< Alias for AST type result */
+
 class declaration_node;
 
 using declaration_node_p = node_p<declaration_node>; /**< Alias for a shared pointer to declaration_node. */
@@ -147,6 +151,14 @@ using var_assign_expression_node_p =
 using var_assign_expression_node_r =
     node_r<var_assign_expression_node>; /**< Alias for var_assign_expression_node result */
 
+class function_call_expression_node;
+
+using function_call_expression_node_p =
+    node_p<function_call_expression_node>; /**< Alias for a shared pointer to function_call_expression_node. */
+
+using function_call_expression_node_r =
+    node_r<function_call_expression_node>; /**< Alias for function_call_expression_node result. */
+
 /**
  * @brief List of statements.
  */
@@ -235,6 +247,12 @@ using compound_statement_node_p =
 
 using compound_statement_node_r = node_r<compound_statement_node>; /**< Alias for compound_statement_node result */
 
+class while_statement_node;
+
+using while_statement_node_p = node_p<while_statement_node>; /**< Alias for a shared pointer to while_statement_node. */
+
+using while_statement_node_r = node_r<while_statement_node>; /**< Alias for while_statement_node result */
+
 } // namespace ast
 } // namespace furc
 

furc/include/furc/ast/statement.hpp

@@ -1,6 +1,7 @@
 #ifndef FURC_AST_STATEMENT_HPP
 #define FURC_AST_STATEMENT_HPP
 
+#include "furc/ast/fwd.hpp"
 #include "furc/ast/node.hpp"
 
 #include <optional>
@@ -17,6 +18,7 @@ enum class statement_node_t {
     Return,      /**< Return statement */
     If,          /**< If statement */
     Compound,    /**< Compound statement */
+    While,       /**< While loop statement. */
 };
 
 /**
@@ -191,6 +193,51 @@ private:
     struct body m_body; /**< The body handle. */
 };
 
+/**
+ * @brief while statement AST node.
+ */
+class while_statement_node final : public statement_node, public abstract_node {
+public:
+    /**
+     * @brief Construct a new while statement AST node.
+     *
+     * @param location Node location.
+     * @param body Body handle.
+     */
+    while_statement_node(struct location location, expression_node_p&& cond, statement_node_p&& body)
+      : abstract_node(location), m_cond(std::move(cond)), m_body(std::move(body)) {}
+public:
+    /**
+     * @brief Returns this node's condition expression.
+     *
+     * @return The condition expression.
+     */
+    const expression_node_p& condition() const { return m_cond; }
+
+    /**
+     * @brief Returns this node's body handle.
+     *
+     * @return The body handle.
+     */
+    const statement_node_p& body() const { return m_body; }
+public:
+    /**
+     * @brief Returns this node's statement type.
+     *
+     * @return statement_node_t::while.
+     */
+    statement_node_t statement_type() const override { return statement_node_t::While; }
+public:
+    void accept(visitor& visitor) const override;
+
+    std::ostream& print(std::ostream& os) const override;
+protected:
+    bool equal(const node& rhs) const override;
+private:
+    expression_node_p m_cond; /**< The condition expression. */
+    statement_node_p  m_body; /**< The body handle. */
+};
+
 } // namespace ast
 } // namespace furc
 

furc/include/furc/ast/visitor.hpp

@@ -82,6 +82,14 @@ public:
      */
     virtual void visit(const var_assign_expression_node& node) {}
 
+    /**
+     * @brief Visit a function_call_expression_node.
+     * @see function_call_expression_node
+     *
+     * @param node Node.
+     */
+    virtual void visit(const function_call_expression_node& node) {}
+
     /**
      * @brief Visit a function_declaration_node.
      * @see function_declaration_node
@@ -122,6 +130,14 @@ public:
      */
     virtual void visit(const compound_statement_node& node) {}
 
+    /**
+     * @brief Visit a while_statement_node.
+     * @see while_statement_node
+     *
+     * @param node Node.
+     */
+    virtual void visit(const while_statement_node& node) {}
+
     /**
      * @brief Visit an AST error.
      *

furc/include/furc/back/furvm.hpp

@@ -0,0 +1,43 @@
+#ifndef FURC_BACK_FURVM_HPP
+#define FURC_BACK_FURVM_HPP
+
+#include "furlang/ir/operand.hpp"
+
+#include <cstddef>
+#include <furlang/ir/function.hpp>
+#include <furlang/ir/instruction.hpp>
+#include <furlang/ir/module.hpp>
+#include <furvm/fwd.hpp>
+#include <furvm/module.hpp>
+#include <unordered_map>
+#include <vector>
+
+namespace furc {
+namespace back {
+
+class furvm_generator {
+public:
+    furvm_generator() = default;
+public:
+    static furvm::mod generate(furlang::ir::mod& mod);
+private:
+    static void generate_function(furvm::mod& mod, const furlang::ir::function& function);
+
+    struct function_context {
+        std::unordered_map<furlang::ir::block_index, std::size_t>              blockOffsets;
+        std::unordered_map<furlang::ir::block_index, std::vector<std::size_t>> incompleteJumps;
+
+        std::unordered_map<furlang::ir::register_operand, furvm::variable_t> variables;
+        furvm::variable_t                                                    variableCounter{ 0 };
+    };
+
+    static void generate_instruction(furvm::mod& mod, function_context& ctx, const furlang::ir::instruction& instr);
+    static void generate_operand(furvm::mod& mod, function_context& ctx, const furlang::ir::operand& operand);
+
+    static void generate_jump(furvm::mod& mod, function_context& ctx, furlang::ir::block_index block, bool conditional);
+};
+
+} // namespace back
+} // namespace furc
+
+#endif // FURC_BACK_FURVM_HPP

furc/include/furc/front/ir_generator.hpp

@@ -22,11 +22,13 @@ public:
     ir_generator(const ir_generator&)            = delete;
     ir_generator& operator=(const ir_generator&) = delete;
 public:
-    furlang::ir::module&& move_module() { return std::move(m_module); }
+    furlang::ir::mod&& move_module() { return std::move(m_module); }
 public:
     void visit(const ast::function_definition_node& funcDef) override;
+    void visit(const ast::function_declaration_node& funcDecl) override;
     void visit(const ast::return_statement_node& returnStmt) override;
     void visit(const ast::if_statement_node& node) override;
+    void visit(const ast::while_statement_node& node) override;
     void visit(const ast::compound_statement_node& node) override;
     void visit(const ast::string_literal_node& node) override;
     void visit(const ast::integer_literal_node& node) override;
@@ -34,6 +36,7 @@ public:
     void visit(const ast::unary_op_expression_node& node) override;
     void visit(const ast::binary_op_expression_node& node) override;
     void visit(const ast::var_assign_expression_node& node) override;
+    void visit(const ast::function_call_expression_node& node) override;
 private:
     template <typename T, typename... Args>
     void push(Args&&... args) {
@@ -42,9 +45,9 @@ private:
         }
     }
 
-    furlang::ir::block_index push_block();
+    furlang::ir::block_index push_block(bool validate = true);
 private:
-    furlang::ir::module                    m_module;
+    furlang::ir::mod                       m_module;
     std::unique_ptr<furlang::ir::function> m_currentFunction;
     std::shared_ptr<furlang::ir::block>    m_currentBlock;
     ir_register                            m_registerCounter = 0;

furc/include/furc/front/parser.hpp

@@ -1,6 +1,7 @@
 #ifndef FURC_FRONT_PARSER_HPP
 #define FURC_FRONT_PARSER_HPP
 
+#include "furc/ast/declaration.hpp"
 #include "furc/ast/fwd.hpp"
 #include "furc/front/lexer.hpp"
 #include "furlang/arena.hpp"
@@ -23,7 +24,7 @@ public:
      * @param filename Filename for debugging.
      * @param content Content.
      */
-    parser(std::string_view filename, std::string_view content);
+    parser(furlang::arena& arena, std::string_view filename, std::string_view content);
 
     /**
      * @brief Construct a new parser from file.
@@ -32,7 +33,8 @@ public:
      *
      * @param filename Name of the file.
      */
-    parser(std::string_view filename);
+    parser(furlang::arena& arena, std::string_view filename);
+
     ~parser() = default;
 
     /**
@@ -40,13 +42,12 @@ public:
      */
     parser(parser&&) = default;
 
-    parser(const parser&) = delete;
-
     /**
      * @brief Move constructor.
      */
     parser& operator=(parser&&) = default;
 
+    parser(const parser&)            = delete;
     parser& operator=(const parser&) = delete;
 public:
     /**
@@ -56,6 +57,8 @@ public:
      */
     ast::program_node_r parse() &;
 private:
+    ast::type_r parse_type();
+
     ast::declaration_node_r parse_declaration();
     ast::statement_node_r   parse_statement();
     ast::expression_node_r  parse_expression(std::uint32_t precedence = 16);
@@ -73,7 +76,7 @@ private:
     std::string          m_filename;
     std::string          m_content;
     lexer                m_lexer;
-    furlang::arena       m_arena;
+    furlang::arena*      m_arena;
     std::vector<token_r> m_peekBuffer;
 };
 

furc/include/furc/front/post_process.hpp

@@ -0,0 +1,41 @@
+#ifndef FURC_FRONT_POST_PROCESS_HPP
+#define FURC_FRONT_POST_PROCESS_HPP
+
+#include "furlang/ir/module.hpp"
+
+#include <vector>
+
+namespace furc {
+namespace front {
+
+/**
+ * @brief Post process pipeline.
+ */
+class post_process {
+public:
+    enum stage { // NOLINT
+        Ssa,
+        Sccp,
+        Adce,
+        DeSsa,
+    };
+public:
+    post_process()  = default;
+    ~post_process() = default;
+
+    post_process(post_process&&) noexcept            = default;
+    post_process& operator=(post_process&&) noexcept = default;
+    post_process(const post_process&)                = delete;
+    post_process& operator=(const post_process&)     = delete;
+public:
+    void push_stage(stage stage) { m_stages.push_back(stage); }
+public:
+    void process(furlang::ir::mod& mod);
+private:
+    std::vector<stage> m_stages;
+};
+
+} // namespace front
+} // namespace furc
+
+#endif // FURC_FRONT_POST_PROCESS_HPP

furc/include/furc/front/token.hpp

@@ -54,6 +54,9 @@ enum class token_t {
     GreaterThan, /**< `>` */
     LessEq,      /**< `<=` */
     GreaterEq,   /**< `>=` */
+
+    SlimArrow, /**< `->` */
+    FatArrow,  /**< `=>` */
 };
 
 static inline std::ostream& operator<<(std::ostream& os, token_t type) {
@@ -92,6 +95,8 @@ static inline std::ostream& operator<<(std::ostream& os, token_t type) {
     case token_t::GreaterThan: return os << ">";
     case token_t::LessEq: return os << "<=";
     case token_t::GreaterEq: return os << ">=";
+    case token_t::SlimArrow: return os << "->";
+    case token_t::FatArrow: return os << "=>";
     }
     return os;
 }
@@ -132,6 +137,8 @@ static inline std::string operator+(const std::string& str, token_t type) {
     case token_t::GreaterThan: return str + ">";
     case token_t::LessEq: return str + "<=";
     case token_t::GreaterEq: return str + ">=";
+    case token_t::SlimArrow: return str + "->";
+    case token_t::FatArrow: return str + "=>";
     }
     return str;
 }
@@ -140,11 +147,20 @@ static inline std::string operator+(const std::string& str, token_t type) {
  * @brief Keyword token.
  */
 enum class keyword_token {
-    None,   /**< None */
-    Func,   /**< `func` */
-    Return, /**< `return` */
-    If,     /**< `if` */
-    Else,   /**< `else` */
+    None,      /**< None */
+    Func,      /**< `func` */
+    Return,    /**< `return` */
+    If,        /**< `if` */
+    Else,      /**< `else` */
+    While,     /**< `while` */
+    Import,    /**< `import` */
+    Native,    /**< `native` */
+    Public,    /**< `public` */
+    Private,   /**< `private` */
+    Pointerof, /**< `pointerof` */
+    Sizeof,    /**< `sizeof` */
+
+    Int32, /**< `int32` */
 };
 
 static inline std::ostream& operator<<(std::ostream& os, keyword_token keyword) {
@@ -154,6 +170,14 @@ static inline std::ostream& operator<<(std::ostream& os, keyword_token keyword)
     case keyword_token::Return: return os << "return";
     case keyword_token::If: return os << "if";
     case keyword_token::Else: return os << "else";
+    case keyword_token::While: return os << "while";
+    case keyword_token::Import: return os << "import";
+    case keyword_token::Native: return os << "native";
+    case keyword_token::Public: return os << "public";
+    case keyword_token::Private: return os << "private";
+    case keyword_token::Pointerof: return os << "pointerof";
+    case keyword_token::Sizeof: return os << "sizeof";
+    case keyword_token::Int32: return os << "int32";
     }
     return os;
 }
@@ -165,6 +189,14 @@ static inline std::string operator+(const std::string& str, keyword_token keywor
     case keyword_token::Return: return str + "return";
     case keyword_token::If: return str + "if";
     case keyword_token::Else: return str + "else";
+    case keyword_token::While: return str + "while";
+    case keyword_token::Import: return str + "import";
+    case keyword_token::Native: return str + "native";
+    case keyword_token::Public: return str + "public";
+    case keyword_token::Private: return str + "private";
+    case keyword_token::Pointerof: return str + "pointerof";
+    case keyword_token::Sizeof: return str + "sizeof";
+    case keyword_token::Int32: return str + "int32";
     }
     return str;
 }

furc/src/ast.cpp

@@ -37,6 +37,8 @@ std::ostream& operator<<(std::ostream& os, unaryop_expression_node_t type) {
     case unaryop_expression_node_t::PostfixIncrement: return os << "++";
     case unaryop_expression_node_t::PrefixDecrement:
     case unaryop_expression_node_t::PostfixDecrement: return os << "--";
+    case unaryop_expression_node_t::Pointerof: return os << "pointerof";
+    case unaryop_expression_node_t::Sizeof: return os << "sizeof";
     }
     return os;
 }
@@ -54,6 +56,8 @@ std::ostream& unary_op_expression_node::print(std::ostream& os) const {
     case unaryop_expression_node_t::PrefixDecrement: return os << '(' << m_type << *m_node << ')';
     case unaryop_expression_node_t::PostfixIncrement:
     case unaryop_expression_node_t::PostfixDecrement: return os << '(' << *m_node << m_type << ')';
+    case unaryop_expression_node_t::Pointerof: return os << "pointerof " << *m_node;
+    case unaryop_expression_node_t::Sizeof: return os << "sizeof " << *m_node;
     }
     return os;
 }
@@ -108,6 +112,26 @@ bool var_assign_expression_node::equal(const node& rhsNode) const {
     return expression_node::equal(rhsNode) && m_compound == rhs.m_compound && m_lhs == rhs.m_lhs && m_rhs == rhs.m_rhs;
 }
 
+void function_call_expression_node::accept(visitor& visitor) const {
+    visitor.visit(*this);
+}
+
+std::ostream& function_call_expression_node::print(std::ostream& os) const {
+    os << *m_func << '(';
+    bool first = true;
+    for (const auto& arg : m_args) {
+        if (!first) os << ", ";
+        first = false;
+        os << *arg;
+    }
+    return os << ')';
+}
+
+bool function_call_expression_node::equal(const node& rhsNode) const {
+    const auto& rhs = dynamic_cast<const function_call_expression_node&>(rhsNode);
+    return expression_node::equal(rhsNode) && m_func == rhs.m_func && m_args == rhs.m_args;
+}
+
 bool declaration_node::equal(const node& rhs) const {
     return declaration_type() == dynamic_cast<const declaration_node&>(rhs).declaration_type();
 }
@@ -186,6 +210,18 @@ bool compound_statement_node::equal(const node& rhs) const {
     return statement_node::equal(rhs) && m_body == dynamic_cast<const compound_statement_node&>(rhs).m_body;
 }
 
+void while_statement_node::accept(visitor& visitor) const {
+    visitor.visit(*this);
+}
+
+std::ostream& while_statement_node::print(std::ostream& os) const {
+    return os << m_body;
+}
+
+bool while_statement_node::equal(const node& rhs) const {
+    return statement_node::equal(rhs) && m_body == dynamic_cast<const while_statement_node&>(rhs).m_body;
+}
+
 void program_node::accept(visitor& visitor) const {
     for (const auto& decl : m_declarations) {
         decl->accept(visitor);

furc/src/back/furvm.cpp

@@ -0,0 +1,196 @@
+#include "furc/back/furvm.hpp"
+
+#include "furlang/ir/function.hpp"
+#include "furlang/ir/instruction.hpp"
+#include "furvm/function.hpp"
+#include "furvm/fwd.hpp"
+
+#include <furvm/instruction.hpp>
+#include <stdexcept>
+
+namespace furc::back {
+
+furvm::mod furvm_generator::generate(furlang::ir::mod& mod) {
+    furvm::mod vmMod;
+
+    for (const auto& function : mod.functions()) {
+        generate_function(vmMod, *function);
+    }
+
+    return vmMod;
+}
+
+void furvm_generator::generate_function(furvm::mod& mod, const furlang::ir::function& function) {
+    furvm::function_sig signature; // TODO: Complete
+
+    switch (function.type()) {
+    case furlang::ir::function_t::Normal: {
+        if (function.access() == furlang::ir::function_access_t::Public)
+            mod.emplace_function(function.name(), std::move(signature), mod.bytecode().size()).dispatch();
+        else
+            mod.emplace_function(std::move(signature), mod.bytecode().size()).dispatch();
+
+        function_context ctx;
+        for (furlang::ir::block_index idx = 0; idx < function.blocks().size(); ++idx) {
+            if (auto it = ctx.incompleteJumps.find(idx); it != ctx.incompleteJumps.end()) {
+                for (std::size_t offset : it->second) {
+                    mod.bytecode()[offset] = mod.bytecode().size() - offset - 1;
+                }
+                ctx.incompleteJumps.erase(it);
+            }
+
+            ctx.blockOffsets[idx] = mod.bytecode().size();
+            for (const auto& instr : function.blocks()[idx]->instructions())
+                generate_instruction(mod, ctx, *instr);
+            generate_instruction(mod, ctx, *function.blocks()[idx]->exit());
+        }
+    } break;
+    case furlang::ir::function_t::Import: {
+        throw std::runtime_error("unimplemented");
+        // mod.emplace_function_private(function.name(), function.param_count(), mod.bytecode().size()).dispatch();
+    } break;
+    case furlang::ir::function_t::Native: {
+        if (function.access() == furlang::ir::function_access_t::Public)
+            mod.emplace_function(function.name(), std::move(signature), function.name()).dispatch();
+        else
+            mod.emplace_function(std::move(signature), function.name()).dispatch();
+    } break;
+    }
+}
+
+static inline furvm::instruction_t op_type(furlang::ir::instruction_t type) {
+    switch (type) {
+    // Unary
+    case furlang::ir::instruction_t::Pointerof: return furvm::instruction_t::Pointerof;
+    case furlang::ir::instruction_t::Sizeof: return furvm::instruction_t::Sizeof;
+
+    // Binary
+    case furlang::ir::instruction_t::Add: return furvm::instruction_t::Add;
+    case furlang::ir::instruction_t::Sub: return furvm::instruction_t::Sub;
+    case furlang::ir::instruction_t::Mul: return furvm::instruction_t::Mul;
+    case furlang::ir::instruction_t::Div: return furvm::instruction_t::Div;
+    case furlang::ir::instruction_t::Mod: return furvm::instruction_t::Mod;
+    case furlang::ir::instruction_t::Eq: return furvm::instruction_t::Equals;
+    case furlang::ir::instruction_t::NotEq: return furvm::instruction_t::NotEquals;
+    case furlang::ir::instruction_t::LessThan: return furvm::instruction_t::LessThan;
+    case furlang::ir::instruction_t::GreaterThan: return furvm::instruction_t::GreaterThan;
+    case furlang::ir::instruction_t::LessEq: return furvm::instruction_t::LessEqual;
+    case furlang::ir::instruction_t::GreaterEq: return furvm::instruction_t::GreaterEqual;
+
+    default: throw std::runtime_error("unreachable");
+    }
+}
+
+void furvm_generator::generate_instruction(furvm::mod& mod,
+    function_context&                                  ctx,
+    const furlang::ir::instruction&                    instr) {
+    for (const auto& operand : instr.sources())
+        generate_operand(mod, ctx, *operand);
+
+    switch (instr.type()) {
+    case furlang::ir::instruction_t::Assign: {
+        if (ctx.variables.find(instr.destination().reg()) == ctx.variables.end()) {
+            ctx.variables[instr.destination().reg()] = ctx.variableCounter++;
+        }
+        auto var = ctx.variables[instr.destination().reg()];
+        mod.bytecode().push_back(static_cast<furvm::byte>(furvm::instruction_t::Store));
+        mod.bytecode().push_back((var >> 0) & 0xFF);
+        mod.bytecode().push_back((var >> 8) & 0xFF);
+        static_assert(sizeof(var) == 2, "sizeof(furvm::variable_t) has changed");
+    } break;
+    case furlang::ir::instruction_t::Add:
+    case furlang::ir::instruction_t::Sub:
+    case furlang::ir::instruction_t::Mul:
+    case furlang::ir::instruction_t::Div:
+    case furlang::ir::instruction_t::Mod:
+    case furlang::ir::instruction_t::Eq:
+    case furlang::ir::instruction_t::NotEq:
+    case furlang::ir::instruction_t::LessThan:
+    case furlang::ir::instruction_t::GreaterThan:
+    case furlang::ir::instruction_t::LessEq:
+    case furlang::ir::instruction_t::GreaterEq: {
+        mod.bytecode().push_back(static_cast<furvm::byte>(op_type(instr.type())));
+
+        if (ctx.variables.find(instr.destination().reg()) == ctx.variables.end()) {
+            ctx.variables[instr.destination().reg()] = ctx.variableCounter++;
+        }
+        auto var = ctx.variables[instr.destination().reg()];
+        mod.bytecode().push_back(static_cast<furvm::byte>(furvm::instruction_t::Store));
+        mod.bytecode().push_back((var >> 0) & 0xFF);
+        mod.bytecode().push_back((var >> 8) & 0xFF);
+        static_assert(sizeof(var) == 2, "sizeof(furvm::variable_t) has changed");
+    } break;
+    case furlang::ir::instruction_t::Pointerof:
+    case furlang::ir::instruction_t::Sizeof: {
+        mod.bytecode().push_back(static_cast<furvm::byte>(op_type(instr.type())));
+
+        if (ctx.variables.find(instr.destination().reg()) == ctx.variables.end()) {
+            ctx.variables[instr.destination().reg()] = ctx.variableCounter++;
+        }
+        auto var = ctx.variables[instr.destination().reg()];
+        mod.bytecode().push_back(static_cast<furvm::byte>(furvm::instruction_t::Store));
+        mod.bytecode().push_back((var >> 0) & 0xFF);
+        mod.bytecode().push_back((var >> 8) & 0xFF);
+        static_assert(sizeof(var) == 2, "sizeof(furvm::variable_t) has changed");
+    } break;
+    case furlang::ir::instruction_t::Branch: {
+        const auto& branch = dynamic_cast<const furlang::ir::branch_instruction&>(instr);
+        generate_jump(mod, ctx, branch.block(), false);
+    } break;
+    case furlang::ir::instruction_t::BranchCond: {
+        const auto& branch = dynamic_cast<const furlang::ir::branch_cond_instruction&>(instr);
+        generate_jump(mod, ctx, branch.if_block(), true);
+        generate_jump(mod, ctx, branch.else_block(), false);
+    } break;
+    case furlang::ir::instruction_t::Return: {
+        mod.bytecode().push_back(static_cast<furvm::byte>(furvm::instruction_t::Return));
+    } break;
+    case furlang::ir::instruction_t::Call: {
+        const auto& call = dynamic_cast<const furlang::ir::call_instruction&>(instr);
+
+        // TODO: Implement a queue for unknown functions
+        furvm::function_id func = mod.function_at(call.name(), furvm::function_sig{}).id(); // TODO: Complete
+        mod.bytecode().push_back(static_cast<furvm::byte>(furvm::instruction_t::Call));
+        mod.bytecode().push_back((func >> 0) & 0xFF);
+        mod.bytecode().push_back((func >> 8) & 0xFF);
+    } break;
+    case furlang::ir::instruction_t::Alloca: throw std::runtime_error("unimplemented instruction");
+    case furlang::ir::instruction_t::Phi: throw std::runtime_error("unreachable");
+    }
+}
+
+void furvm_generator::generate_operand(furvm::mod& mod, function_context& ctx, const furlang::ir::operand& operand) {
+    switch (operand.type()) {
+    case furlang::ir::operand_t::Register: {
+        if (ctx.variables.find(operand.reg()) == ctx.variables.end()) throw std::runtime_error("unregistered register");
+        auto var = ctx.variables[operand.reg()];
+        mod.bytecode().push_back(static_cast<furvm::byte>(furvm::instruction_t::Load));
+        mod.bytecode().push_back((var >> 0) & 0xFF);
+        mod.bytecode().push_back((var >> 8) & 0xFF);
+        static_assert(sizeof(var) == 2, "sizeof(furvm::variable_t) has changed");
+    } break;
+    case furlang::ir::operand_t::Integer: {
+        mod.bytecode().push_back(static_cast<furvm::byte>(furvm::instruction_t::PushS32));
+        mod.bytecode().push_back(operand.integer());
+    } break;
+    case furlang::ir::operand_t::Variable:
+    case furlang::ir::operand_t::String: throw std::runtime_error("unimplemented operand");
+    case furlang::ir::operand_t::None: throw std::runtime_error("unreachable");
+    }
+}
+
+void furvm_generator::generate_jump(furvm::mod& mod,
+    function_context&                           ctx,
+    furlang::ir::block_index                    block,
+    bool                                        conditional) {
+    mod.bytecode().push_back(
+        static_cast<furvm::byte>(conditional ? furvm::instruction_t::JumpNotZero : furvm::instruction_t::Jump));
+    if (auto it = ctx.blockOffsets.find(block); it != ctx.blockOffsets.end()) {
+        mod.bytecode().push_back(it->second - mod.bytecode().size() - 1);
+    } else {
+        ctx.incompleteJumps[block].push_back(mod.bytecode().size());
+        mod.bytecode().push_back(0);
+    }
+}
+
+} // namespace furc::back

furc/src/front/ir_generator.cpp

@@ -4,8 +4,14 @@
 #include "furc/ast/expression.hpp"  // IWYU pragma: keep
 #include "furc/ast/literal.hpp"     // IWYU pragma: keep
 #include "furc/ast/statement.hpp"   // IWYU pragma: keep
+#include "furlang/ir/function.hpp"
+#include "furlang/ir/instruction.hpp"
+#include "furlang/ir/operand.hpp"
 
 #include <cassert>
+#include <memory>
+#include <stdexcept>
+#include <vector>
 
 namespace furc::front {
 
@@ -14,7 +20,11 @@ namespace ir = furlang::ir;
 }
 
 void ir_generator::visit(const ast::function_definition_node& funcDef) {
-    m_currentFunction = std::make_unique<furlang::ir::function>(std::string(funcDef.name()));
+    furlang::ir::function_access_t access = (funcDef.access() == ast::declaration_access_t::Public)
+                                                ? furlang::ir::function_access_t::Public
+                                                : furlang::ir::function_access_t::Private;
+
+    m_currentFunction = std::make_unique<furlang::ir::function>(std::string(funcDef.name()), access, 0);
 
     push_block();
     for (const auto& stmt : funcDef.body().statements) {
@@ -26,6 +36,21 @@ void ir_generator::visit(const ast::function_definition_node& funcDef) {
     m_module.push(std::move(m_currentFunction));
 }
 
+void ir_generator::visit(const ast::function_declaration_node& funcDecl) {
+    if (funcDecl.type() == ast::function_declaration_node_t::Normal) return;
+
+    furlang::ir::function_t type = funcDecl.type() == ast::function_declaration_node_t::Import
+                                       ? furlang::ir::function_t::Import
+                                       : furlang::ir::function_t::Native;
+
+    furlang::ir::function_access_t access = (funcDecl.access() == ast::declaration_access_t::Public)
+                                                ? furlang::ir::function_access_t::Public
+                                                : furlang::ir::function_access_t::Private;
+
+    m_module.push(
+        std::make_unique<furlang::ir::function>(std::string(funcDecl.name()), access, funcDecl.params().size(), type));
+}
+
 void ir_generator::visit(const ast::return_statement_node& returnStmt) {
     if (returnStmt.value().has_value()) {
         returnStmt.value().value()->accept(*this);
@@ -55,6 +80,33 @@ void ir_generator::visit(const ast::if_statement_node& node) {
     push_block(); // merge block
 }
 
+void ir_generator::visit(const ast::while_statement_node& node) {
+    node.condition()->accept(*this);
+    ir_register                cond      = m_registerCounter - 1;
+    std::shared_ptr<ir::block> entry     = m_currentBlock;
+    ir::block_index            headerIdx = m_currentFunction->blocks().size();
+
+    push_block(false); // loop header
+    push<ir::branch_instruction>(m_currentFunction->blocks().size());
+
+    push_block(); // loop condition
+    node.condition()->accept(*this);
+    std::shared_ptr<ir::block> condBlock = m_currentBlock;
+    ir_register                cond2     = m_registerCounter - 1;
+
+    push_block(false); // loop body
+    node.body()->accept(*this);
+    push<ir::branch_instruction>(headerIdx);
+
+    entry->emplace<ir::branch_cond_instruction>(ir::operand::new_reg(cond),
+        headerIdx,
+        m_currentFunction->blocks().size());
+    condBlock->emplace<ir::branch_cond_instruction>(ir::operand::new_reg(cond2),
+        m_currentFunction->blocks().size() - 1,
+        m_currentFunction->blocks().size());
+    push_block(); // merge block
+}
+
 void ir_generator::visit(const ast::compound_statement_node& node) {
     for (const auto& stmt : node.body().statements) {
         stmt.value()->accept(*this);
@@ -80,23 +132,36 @@ void ir_generator::visit(const ast::var_read_expression_node& node) {
     }
 }
 
-void ir_generator::visit(const ast::unary_op_expression_node& node) {
-    throw std::runtime_error("unimplemented");
+static inline furlang::ir::instruction_t unary_op_instruction_t(ast::unaryop_expression_node_t type) {
+    switch (type) {
+    case ast::unaryop_expression_node_t::Pointerof: return furlang::ir::instruction_t::Pointerof;
+    case ast::unaryop_expression_node_t::Sizeof: return furlang::ir::instruction_t::Sizeof;
+    default: throw std::runtime_error("unimplemented");
+    }
 }
 
-static inline furlang::ir::binary_op_instruction_t binary_op_instruction_t(ast::binop_expression_node_t type) {
+void ir_generator::visit(const ast::unary_op_expression_node& node) {
+    node.get_node()->accept(*this);
+    ir_register src = m_registerCounter - 1;
+    ir_register dst = m_registerCounter++;
+    push<furlang::ir::unary_instruction>(unary_op_instruction_t(node.type()),
+        ir::operand::new_reg(src),
+        ir::operand::new_reg(dst));
+}
+
+static inline furlang::ir::instruction_t binary_op_instruction_t(ast::binop_expression_node_t type) {
     switch (type) {
-    case ast::binop_expression_node_t::Add: return furlang::ir::binary_op_instruction_t::Add;
-    case ast::binop_expression_node_t::Sub: return furlang::ir::binary_op_instruction_t::Sub;
-    case ast::binop_expression_node_t::Mul: return furlang::ir::binary_op_instruction_t::Mul;
-    case ast::binop_expression_node_t::Div: return furlang::ir::binary_op_instruction_t::Div;
-    case ast::binop_expression_node_t::Mod: return furlang::ir::binary_op_instruction_t::Mod;
-    case ast::binop_expression_node_t::Equal: return furlang::ir::binary_op_instruction_t::Eq;
-    case ast::binop_expression_node_t::NotEqual: return furlang::ir::binary_op_instruction_t::NotEq;
-    case ast::binop_expression_node_t::LessThan: return furlang::ir::binary_op_instruction_t::LessThan;
-    case ast::binop_expression_node_t::GreaterThan: return furlang::ir::binary_op_instruction_t::GreaterThan;
-    case ast::binop_expression_node_t::LessEqual: return furlang::ir::binary_op_instruction_t::LessEq;
-    case ast::binop_expression_node_t::GreaterEqual: return furlang::ir::binary_op_instruction_t::GreaterEq;
+    case ast::binop_expression_node_t::Add: return furlang::ir::instruction_t::Add;
+    case ast::binop_expression_node_t::Sub: return furlang::ir::instruction_t::Sub;
+    case ast::binop_expression_node_t::Mul: return furlang::ir::instruction_t::Mul;
+    case ast::binop_expression_node_t::Div: return furlang::ir::instruction_t::Div;
+    case ast::binop_expression_node_t::Mod: return furlang::ir::instruction_t::Mod;
+    case ast::binop_expression_node_t::Equal: return furlang::ir::instruction_t::Eq;
+    case ast::binop_expression_node_t::NotEqual: return furlang::ir::instruction_t::NotEq;
+    case ast::binop_expression_node_t::LessThan: return furlang::ir::instruction_t::LessThan;
+    case ast::binop_expression_node_t::GreaterThan: return furlang::ir::instruction_t::GreaterThan;
+    case ast::binop_expression_node_t::LessEqual: return furlang::ir::instruction_t::LessEq;
+    case ast::binop_expression_node_t::GreaterEqual: return furlang::ir::instruction_t::GreaterEq;
     case ast::binop_expression_node_t::None:
     default: throw std::runtime_error("unreachable");
     }
@@ -108,7 +173,7 @@ void ir_generator::visit(const ast::binary_op_expression_node& node) {
     node.rhs()->accept(*this);
     ir_register rhs = m_registerCounter - 1;
     ir_register dst = m_registerCounter++;
-    push<furlang::ir::binary_op_instruction>(binary_op_instruction_t(node.type()),
+    push<furlang::ir::binary_instruction>(binary_op_instruction_t(node.type()),
         ir::operand::new_reg(lhs),
         ir::operand::new_reg(rhs),
         ir::operand::new_reg(dst));
@@ -120,26 +185,42 @@ void ir_generator::visit(const ast::var_assign_expression_node& node) {
     assert(node.lhs()->expression_type() == ast::expression_node_t::VarRead);
     auto lhs = std::dynamic_pointer_cast<ast::var_read_expression_node>(node.lhs());
 
-    ir_register reg = 0;
-    if (auto it = m_variables.find(lhs->get_name()); it != m_variables.end()) {
-        reg = it->second;
-    } else {
-        m_variables[lhs->get_name()] = reg = m_registerCounter++;
-    }
+    ir_register reg = m_registerCounter++;
 
     auto compound = node.compound();
     if (compound != ast::binop_expression_node_t::None) {
-        push<ir::binary_op_instruction>(binary_op_instruction_t(compound),
+        push<ir::binary_instruction>(binary_op_instruction_t(compound),
             ir::operand::new_reg(reg),
             ir::operand::new_reg(rhs),
             ir::operand::new_reg(reg));
     } else {
         push<ir::assign_instruction>(ir::operand::new_reg(rhs), ir::operand::new_reg(reg));
     }
+
+    if (auto it = m_variables.find(lhs->get_name()); it != m_variables.end()) {
+        push<ir::assign_instruction>(ir::operand::new_reg(reg), ir::operand::new_reg(it->second));
+    } else {
+        m_variables[lhs->get_name()] = reg;
+    }
 }
 
-furlang::ir::block_index ir_generator::push_block() {
-    if (!m_currentFunction->blocks().empty() && !m_currentFunction->blocks().back()->has_exit()) {
+void ir_generator::visit(const ast::function_call_expression_node& node) {
+    std::vector<ir::operand> args;
+    args.reserve(node.args().size());
+    for (const auto& arg : node.args()) {
+        arg->accept(*this);
+        args.push_back(ir::operand::new_reg(m_registerCounter - 1));
+    }
+    if (node.func()->expression_type() != ast::expression_node_t::VarRead)
+        throw std::runtime_error("invalid function call left-hand-side expression");
+
+    push<ir::call_instruction>(dynamic_cast<const ast::var_read_expression_node&>(*node.func()).get_name(),
+        ir::operand::new_reg(m_registerCounter++),
+        std::move(args));
+}
+
+furlang::ir::block_index ir_generator::push_block(bool validate) {
+    if (validate && !m_currentFunction->blocks().empty() && !m_currentFunction->blocks().back()->has_exit()) {
         throw std::runtime_error(
             "block " + std::to_string(m_currentFunction->blocks().size() - 1) + " is lacking an exit");
     }

furc/src/front/lexer.cpp

@@ -1,5 +1,7 @@
 #include "furc/front/lexer.hpp"
 
+#include "furc/front/token.hpp"
+
 #include <cctype>
 #include <limits>
 #include <map>
@@ -97,6 +99,14 @@ token_r lexer::next_token() {
                 { "return", keyword_token::Return },
                 { "if", keyword_token::If },
                 { "else", keyword_token::Else },
+                { "while", keyword_token::While },
+                { "import", keyword_token::Import },
+                { "native", keyword_token::Native },
+                { "public", keyword_token::Public },
+                { "private", keyword_token::Private },
+                { "pointerof", keyword_token::Pointerof },
+                { "sizeof", keyword_token::Sizeof },
+                { "int32", keyword_token::Int32 },
             };
 
             if (auto it = s_keywords.find(value); it != s_keywords.end()) return { location, it->second };
@@ -140,6 +150,8 @@ token_r lexer::next_token() {
             { ">", token_t::GreaterThan },
             { "<=", token_t::LessEq },
             { ">=", token_t::GreaterEq },
+            { "->", token_t::SlimArrow },
+            { "=>", token_t::FatArrow },
         };
 
         token_t     type   = token_t::None;

furc/src/front/parser.cpp

@@ -2,24 +2,27 @@
 
 #include "furc/ast/declaration.hpp" // IWYU pragma: keep
 #include "furc/ast/expression.hpp"  // IWYU pragma: keep
-#include "furc/ast/literal.hpp"     // IWYU pragma: keep
-#include "furc/ast/program.hpp"     // IWYU pragma: keep
-#include "furc/ast/statement.hpp"   // IWYU pragma: keep
+#include "furc/ast/fwd.hpp"
+#include "furc/ast/literal.hpp"   // IWYU pragma: keep
+#include "furc/ast/program.hpp"   // IWYU pragma: keep
+#include "furc/ast/statement.hpp" // IWYU pragma: keep
+#include "furc/front/token.hpp"
 
 #include <fstream>
-#include <iostream>
+#include <optional>
 #include <string>
 #include <unordered_map>
+#include <vector>
 
 namespace furc::front {
 
 using namespace std::string_literals;
 
-parser::parser(std::string_view filename, std::string_view content)
-  : m_filename(filename), m_content(content), m_lexer(m_filename, m_content) {}
+parser::parser(furlang::arena& arena, std::string_view filename, std::string_view content)
+  : m_filename(filename), m_content(content), m_lexer(m_filename, m_content), m_arena(&arena) {}
 
-parser::parser(std::string_view filename)
-  : m_filename(filename) {
+parser::parser(furlang::arena& arena, std::string_view filename)
+  : m_filename(filename), m_arena(&arena) {
     std::ifstream file(m_filename, std::ios_base::binary | std::ios_base::ate);
     if (!file.is_open()) throw std::runtime_error("failed to open file "s.append(m_filename));
     std::streampos size = file.tellg();
@@ -31,53 +34,131 @@ parser::parser(std::string_view filename)
 }
 
 ast::program_node_r parser::parse() & {
-    auto program = m_arena.allocate_shared<ast::program_node>(location{ m_filename });
+    auto program = m_arena->allocate_shared<ast::program_node>(location{ m_filename });
 
     while (peek_token().has_value()) {
         auto decl = parse_declaration();
-        if (decl.has_error()) {
-            program = nullptr;
-        } else if (program != nullptr) {
-            program->push(std::move(decl.value()));
-        }
+        if (decl.has_error()) return ast::program_node_r(ast::error{ decl.error().location });
+        program->push(std::move(decl.value()));
     }
 
-    return program != nullptr ? std::move(program) : ast::program_node_r(ast::error{ location{ m_filename } });
+    return program;
+}
+
+ast::type_r parser::parse_type() {
+    auto token = eat_token(token_t::Keyword);
+    if (token.has_error() || token.value()->keyword != keyword_token::Int32)
+        return ast::type_r(ast::error{ token.error().location });
+    return ast::type("" + token.value()->keyword);
 }
 
 ast::declaration_node_r parser::parse_declaration() {
     const auto& first = peek_token();
+    if (first.has_error()) return ast::declaration_node_r(ast::error{ first.error().location });
     switch (first->type) {
     case token_t::Keyword: {
-        auto first = next_token();
+        token firstToken = *first;
+
+        ast::declaration_access_t accessOverride = ast::declaration_access_t::Implicit;
         switch ((*first)->keyword) {
+        default: break;
+        case keyword_token::Public:
+        case keyword_token::Private: {
+            if ((*first)->keyword == keyword_token::Public) accessOverride = ast::declaration_access_t::Public;
+            if ((*first)->keyword == keyword_token::Private) accessOverride = ast::declaration_access_t::Private;
+            auto kw = eat_token(token_t::Keyword);
+            if (kw.has_error()) return ast::declaration_node_r(ast::error{ kw.error().location });
+            firstToken = *kw;
+        } break;
+        }
+
+        ast::function_declaration_node_t funcDeclType{};
+
+        auto kw = next_token();
+        if (kw.has_error()) return ast::declaration_node_r(ast::error{ kw.error().location });
+        firstToken = *kw;
+        switch (firstToken->keyword) {
+        case keyword_token::Import:
+        case keyword_token::Native: {
+            funcDeclType = (firstToken->keyword == keyword_token::Import) ? ast::function_declaration_node_t::Import
+                                                                          : ast::function_declaration_node_t::Native;
+
+            auto kw = eat_token(token_t::Keyword);
+            if (kw.has_error()) return ast::declaration_node_r(ast::error{ kw.error().location });
+            firstToken = *kw;
+            if (firstToken.value.keyword != keyword_token::Func)
+                return ast::declaration_node_r(ast::error{ firstToken.location });
+        }
         case keyword_token::Func: {
             auto name = eat_token(token_t::Identifier);
             if (name.has_error()) return ast::declaration_node_r(ast::error{ name.error().location });
 
             auto tok = eat_token(token_t::LParen);
             if (tok.has_error()) return ast::declaration_node_r(ast::error{ tok.error().location });
+
+            std::vector<ast::function_declaration_param> params;
+            if (peek_token().has_value() && peek_token()->type != token_t::RParen) {
+                while (true) {
+                    auto name = eat_token(token_t::Identifier);
+                    if (name.has_error()) return ast::declaration_node_r(ast::error{ name.error().location });
+                    auto colon = eat_token(token_t::Colon);
+                    if (colon.has_error()) return ast::declaration_node_r(ast::error{ colon.error().location });
+                    auto type = parse_type();
+                    if (type.has_error()) return ast::declaration_node_r(ast::error{ type.error().location });
+
+                    params.push_back(
+                        ast::function_declaration_param{ std::string(name->value.string), std::move(*type) });
+
+                    auto comma = eat_token(token_t::Comma);
+                    if (comma.has_error()) break;
+                }
+            }
+
             tok = eat_token(token_t::RParen);
             if (tok.has_error()) return ast::declaration_node_r(ast::error{ tok.error().location });
 
+            std::optional<ast::type> returnType;
+            if (peek_token().has_value() && peek_token()->type == token_t::SlimArrow) {
+                auto tok  = next_token();
+                auto type = parse_type();
+                if (type.has_error()) return ast::declaration_node_r(ast::error{ tok->location });
+                returnType = *type;
+            }
+
+            auto access = (funcDeclType == ast::function_declaration_node_t::Import)
+                              ? ast::declaration_access_t::Private
+                              : accessOverride;
+            if (access == ast::declaration_access_t::Implicit) access = ast::declaration_access_t::Public;
+            if (!ast::same_access(accessOverride, access)) return ast::declaration_node_r(ast::error{ tok->location });
+
             const auto& peek = peek_token();
             if (peek.has_error()) return ast::declaration_node_r(ast::error{ peek.error().location });
             switch (peek->type) {
             case token_t::LBrace: {
                 ast::body_r body = parse_body();
                 if (body.has_error()) return ast::declaration_node_r(ast::error{ body.error().location });
-                return m_arena.allocate_shared<ast::function_definition_node>(first->location,
+                if (funcDeclType != ast::function_declaration_node_t::Normal)
+                    return ast::declaration_node_r(ast::error{ body->begin });
+                return m_arena->allocate_shared<ast::function_definition_node>(firstToken.location,
+                    access,
                     name->value.string,
+                    std::move(returnType),
+                    std::move(params),
                     std::move(body.value()));
             }
             case token_t::Semicolon: {
                 m_peekBuffer.clear();
-                return m_arena.allocate_shared<ast::function_declaration_node>(first->location, name->value.string);
+                return m_arena->allocate_shared<ast::function_declaration_node>(firstToken.location,
+                    access,
+                    name->value.string,
+                    std::move(returnType),
+                    std::move(params),
+                    funcDeclType);
             }
             default: return ast::declaration_node_r(ast::error{ tok->location });
             }
         }
-        default: return ast::declaration_node_r(ast::error{ first->location });
+        default: return ast::declaration_node_r(ast::error{ firstToken.location });
         }
     }
     case token_t::None:
@@ -108,13 +189,13 @@ ast::statement_node_r parser::parse_statement() {
             auto tok = next_token();
             if (peek_token()->type == token_t::Semicolon) {
                 next_token();
-                return m_arena.allocate_shared<ast::return_statement_node>(location);
+                return m_arena->allocate_shared<ast::return_statement_node>(location);
             }
 
             auto value = parse_expression();
             auto err   = eat_token(token_t::Semicolon);
             if (err.has_error()) return ast::statement_node_r(ast::error{ err.error().location });
-            return m_arena.allocate_shared<ast::return_statement_node>(location, std::move(value.value()));
+            return m_arena->allocate_shared<ast::return_statement_node>(location, std::move(value.value()));
         }
         case keyword_token::If: {
             auto tok = next_token();
@@ -135,16 +216,34 @@ ast::statement_node_r parser::parse_statement() {
 
                 auto elseBody = parse_statement();
                 if (elseBody.has_error()) return ast::statement_node_r(ast::error{ elseBody.error().location });
-                return m_arena.allocate_shared<ast::if_statement_node>(location,
+                return m_arena->allocate_shared<ast::if_statement_node>(location,
                     std::move(cond.value()),
                     std::move(then.value()),
                     std::move(elseBody.value()));
             }
 
-            return m_arena.allocate_shared<ast::if_statement_node>(location,
+            return m_arena->allocate_shared<ast::if_statement_node>(location,
                 std::move(cond.value()),
                 std::move(then.value()));
         }
+        case keyword_token::While: {
+            auto tok = next_token();
+            auto err = eat_token(token_t::LParen);
+            if (err.has_error()) return ast::statement_node_r(ast::error{ err.error().location });
+
+            auto cond = parse_expression();
+            if (cond.has_error()) return ast::statement_node_r(ast::error{ cond.error().location });
+
+            err = eat_token(token_t::RParen);
+            if (err.has_error()) return ast::statement_node_r(ast::error{ err.error().location });
+
+            auto body = parse_statement();
+            if (body.has_error()) return ast::statement_node_r(ast::error{ body.error().location });
+
+            return m_arena->allocate_shared<ast::while_statement_node>(location,
+                std::move(cond.value()),
+                std::move(body.value()));
+        }
         case keyword_token::None:
         case keyword_token::Func:
         default: break;
@@ -153,7 +252,7 @@ ast::statement_node_r parser::parse_statement() {
     case token_t::LBrace: {
         auto body = parse_body();
         if (body.has_error()) return ast::statement_node_r(ast::error{ body.error().location });
-        return m_arena.allocate_shared<ast::compound_statement_node>(location, std::move(body.value()));
+        return m_arena->allocate_shared<ast::compound_statement_node>(location, std::move(body.value()));
     }
     default: break;
     }
@@ -185,7 +284,7 @@ ast::expression_node_r parser::parse_expression_primary() {
     case token_t::Identifier: {
         auto tok = next_token();
         if (tok.has_error()) return ast::expression_node_r(ast::error{ tok.error().location });
-        return m_arena.allocate_shared<ast::var_read_expression_node>(tok->location, (*tok)->string);
+        return m_arena->allocate_shared<ast::var_read_expression_node>(tok->location, (*tok)->string);
     }
     case token_t::LParen: {
         auto tok  = next_token();
@@ -197,12 +296,12 @@ ast::expression_node_r parser::parse_expression_primary() {
     case token_t::String: {
         auto tok = next_token();
         if (tok.has_error()) return ast::expression_node_r(ast::error{ tok.error().location });
-        return m_arena.allocate_shared<ast::string_literal_node>(tok->location, (*tok)->string);
+        return m_arena->allocate_shared<ast::string_literal_node>(tok->location, (*tok)->string);
     }
     case token_t::Integer: {
         auto tok = next_token();
         if (tok.has_error()) return ast::expression_node_r(ast::error{ tok.error().location });
-        return m_arena.allocate_shared<ast::integer_literal_node>(tok->location, (*tok)->integer);
+        return m_arena->allocate_shared<ast::integer_literal_node>(tok->location, (*tok)->integer);
     }
     default: {
         return ast::expression_node_r(ast::error{ tok->location });
@@ -215,27 +314,43 @@ struct unaryop_info {
     std::uint32_t                  precedence;
 };
 
-ast::expression_node_r parser::parse_expression_unary(std::uint32_t precedence) {
+static inline std::optional<unaryop_info> get_unaryop_info(const token_r& token) {
     static std::unordered_map<token_t, unaryop_info> s_prefixes = {
-        { token_t::Plus, unaryop_info{ ast::unaryop_expression_node_t::Positive, 3 } },
-        { token_t::Minus, unaryop_info{ ast::unaryop_expression_node_t::Negative, 3 } },
+        { token_t::Plus, unaryop_info{ ast::unaryop_expression_node_t::Positive, 2 } },
+        { token_t::Minus, unaryop_info{ ast::unaryop_expression_node_t::Negative, 2 } },
         { token_t::DPlus, unaryop_info{ ast::unaryop_expression_node_t::PrefixIncrement, 2 } },
         { token_t::DMinus, unaryop_info{ ast::unaryop_expression_node_t::PrefixDecrement, 2 } },
     };
+    static std::unordered_map<keyword_token, unaryop_info> s_keywords = {
+        { keyword_token::Pointerof, unaryop_info{ ast::unaryop_expression_node_t::Pointerof, 2 } },
+        { keyword_token::Sizeof, unaryop_info{ ast::unaryop_expression_node_t::Sizeof, 2 } },
+    };
 
+    if (token->type == token_t::Keyword) {
+        auto it = s_keywords.find(token->value.keyword);
+        if (it == s_keywords.end()) return {};
+        return it->second;
+    }
+
+    auto it = s_prefixes.find(token->type);
+    if (it == s_prefixes.end()) return {};
+    return it->second;
+}
+
+ast::expression_node_r parser::parse_expression_unary(std::uint32_t precedence) {
     std::shared_ptr<ast::unary_op_expression_node> result;
     while (true) {
-        auto it = s_prefixes.find(peek_token()->type);
-        if (it == s_prefixes.end()) break;
-        auto current = it->second;
+        auto opt = get_unaryop_info(peek_token());
+        if (!opt.has_value()) break;
+        unaryop_info current = opt.value();
         if (current.precedence >= precedence) break;
         auto token = next_token();
 
         ast::expression_node_p expression;
 
-        auto nextIt = s_prefixes.find(peek_token()->type);
-        if (nextIt != s_prefixes.end()) {
-            auto next = nextIt->second;
+        opt = get_unaryop_info(peek_token());
+        if (opt.has_value()) {
+            auto next = opt.value();
             auto expr = parse_expression_unary(current.precedence + 1);
             if (expr.has_error()) {
                 return ast::expression_node_r(ast::error{ expr.error().location });
@@ -243,7 +358,7 @@ ast::expression_node_r parser::parse_expression_unary(std::uint32_t precedence)
             expression = std::move(std::move(expr.value()));
         }
 
-        result = m_arena.allocate_shared<ast::unary_op_expression_node>(token->location,
+        result = m_arena->allocate_shared<ast::unary_op_expression_node>(token->location,
             current.type,
             std::move(expression));
     }
@@ -268,6 +383,7 @@ enum class rhsop_info_t {
     Unaryop,
     Binop,
     Assignment,
+    FuncCall,
 };
 
 struct rhsop_info {
@@ -280,6 +396,8 @@ struct rhsop_info {
         ast::binop_expression_node_t   assignment;
     };
 
+    bool has_rhs() const { return type == rhsop_info_t::Binop || type == rhsop_info_t::Assignment; }
+
     static rhsop_info create(ast::unaryop_expression_node_t type, std::uint32_t precedence) {
         rhsop_info info{};
         info.type          = rhsop_info_t::Unaryop;
@@ -308,6 +426,14 @@ struct rhsop_info {
         info.assignment    = compound;
         return info;
     }
+
+    static rhsop_info create_function_call() {
+        rhsop_info info{};
+        info.type          = rhsop_info_t::FuncCall;
+        info.precedence    = 1;
+        info.associativity = associativity::Left;
+        return info;
+    }
 };
 
 ast::expression_node_r parser::parse_expression_rhs(ast::expression_node_p&& init, std::uint32_t precedence) {
@@ -332,6 +458,7 @@ ast::expression_node_r parser::parse_expression_rhs(ast::expression_node_p&& ini
         { token_t::GreaterThan, rhsop_info::create(ast::binop_expression_node_t::GreaterThan, 9, associativity::Left) },
         { token_t::LessEq, rhsop_info::create(ast::binop_expression_node_t::LessEqual, 9, associativity::Left) },
         { token_t::GreaterEq, rhsop_info::create(ast::binop_expression_node_t::GreaterEqual, 9, associativity::Left) },
+        { token_t::LParen, rhsop_info::create_function_call() },
     };
 
     ast::expression_node_p lhs = std::move(init);
@@ -343,13 +470,28 @@ ast::expression_node_r parser::parse_expression_rhs(ast::expression_node_p&& ini
         if (current.precedence >= precedence) return lhs;
         auto opToken = next_token();
 
-        ast::expression_node_p rhs;
-        if (current.type != rhsop_info_t::Unaryop) {
+        ast::expression_node_p              rhs;
+        std::vector<ast::expression_node_p> params;
+        if (current.has_rhs()) {
             auto expr = parse_expression_unary(current.precedence + 1); // unary prefix is always right-associative
             if (expr.has_error()) {
                 return ast::expression_node_r(ast::error{ expr.error().location });
             }
             rhs = std::move(expr.value());
+        } else if (current.type == rhsop_info_t::FuncCall && peek_token().has_value()) {
+            if (peek_token()->type != token_t::RParen) {
+                while (true) {
+                    auto expr = parse_expression_unary(16);
+                    if (expr.has_error()) {
+                        return ast::expression_node_r(ast::error{ expr.error().location });
+                    }
+                    params.emplace_back(std::move(expr.value()));
+
+                    if (eat_token(token_t::Comma).has_error()) break;
+                }
+            }
+            auto enclosing = eat_token(token_t::RParen);
+            if (enclosing.has_error()) return ast::expression_node_r(ast::error{ enclosing.error().location });
         }
 
         auto nextIt = s_rhsops.find(peek_token()->type);
@@ -370,22 +512,27 @@ ast::expression_node_r parser::parse_expression_rhs(ast::expression_node_p&& ini
 
         switch (current.type) {
         case rhsop_info_t::Unaryop:
-            lhs = m_arena.allocate_shared<ast::unary_op_expression_node>(opToken->location,
+            lhs = m_arena->allocate_shared<ast::unary_op_expression_node>(opToken->location,
                 current.unary,
                 std::move(lhs));
             break;
         case rhsop_info_t::Binop:
-            lhs = m_arena.allocate_shared<ast::binary_op_expression_node>(opToken->location,
+            lhs = m_arena->allocate_shared<ast::binary_op_expression_node>(opToken->location,
                 current.binary,
                 std::move(lhs),
                 std::move(rhs));
             break;
         case rhsop_info_t::Assignment:
-            lhs = m_arena.allocate_shared<ast::var_assign_expression_node>(opToken->location,
+            lhs = m_arena->allocate_shared<ast::var_assign_expression_node>(opToken->location,
                 current.assignment,
                 std::move(lhs),
                 std::move(rhs));
             break;
+        case rhsop_info_t::FuncCall:
+            lhs = m_arena->allocate_shared<ast::function_call_expression_node>(opToken->location,
+                std::move(lhs),
+                std::move(params));
+            break;
         }
     }
     return lhs;
@@ -427,15 +574,14 @@ const token_r& parser::peek_token() {
 }
 
 token_r parser::eat_token(token_t type) {
-    auto token = next_token();
-    if (token.has_error()) return token;
-    if (token->type != type) {
+    if (const auto& token = peek_token(); token.has_error() || peek_token()->type != type) {
+        if (token.has_error()) return token;
         if (token->type == token_t::None)
             return token_r(token_error{ token->location, token_error_t::UnexpectedToken, ", expected " + type });
         return token_r(
             token_error{ token->location, token_error_t::UnexpectedToken, ""s + token->type + ", expected " + type });
     }
-    return token;
+    return next_token();
 }
 
 } // namespace furc::front

furc/src/front/post_process.cpp

@@ -0,0 +1,605 @@
+#include "furc/front/post_process.hpp"
+
+#include "furlang/ir/function.hpp"
+#include "furlang/ir/instruction.hpp"
+#include "furlang/ir/operand.hpp"
+
+#include <algorithm>
+#include <cstdint>
+#include <limits>
+#include <memory>
+#include <queue>
+#include <set>
+#include <stack>
+#include <stdexcept>
+#include <unordered_map>
+#include <unordered_set>
+#include <utility>
+#include <vector>
+
+namespace furc::front {
+
+using block_idx   = furlang::ir::block_index;
+using register_t  = furlang::ir::register_t;
+using register_op = furlang::ir::register_operand;
+
+static constexpr block_idx INVALID_BLOCK = std::numeric_limits<block_idx>::max();
+
+struct block_info {
+    std::size_t rpoIndex{ 0 };
+
+    std::vector<block_idx> predecessors;
+    std::vector<block_idx> successors;
+
+    block_idx                     idom = INVALID_BLOCK;
+    std::vector<block_idx>        doms;
+    std::unordered_set<block_idx> domFrontiers;
+};
+
+struct register_info {
+    std::unordered_set<block_idx> defSites;
+    std::stack<register_t>        renameStack;
+    std::uint32_t                 nextVersion{ 0 };
+};
+
+struct function_context {
+    explicit function_context(furlang::ir::function* function)
+      : function(function) {
+        build_cfg();
+        compute_rpo();
+    }
+
+    void build_cfg() {
+        for (block_idx idx = 0; idx < function->blocks().size(); ++idx) {
+            const auto& block = function->blocks()[idx];
+
+            for (const auto& instr : block->instructions()) {
+                for (const auto& operand : instr->sources()) {
+                    if (operand->type() != furlang::ir::operand_t::Register) continue;
+                    auto reg = operand->reg();
+                    if (registers[reg].defSites.find(idx) != registers[reg].defSites.end()) continue;
+                    globalRegisters.insert(reg);
+                }
+            }
+
+            for (const auto& instr : block->instructions()) {
+                if (!instr->has_destination() || instr->destination().type() != furlang::ir::operand_t::Register)
+                    continue;
+                auto reg = instr->destination().reg();
+                registers[reg].defSites.insert(idx);
+            }
+
+            for (const auto& operand : block->exit()->sources()) {
+                if (operand->type() != furlang::ir::operand_t::Register) continue;
+                auto reg = operand->reg();
+                if (registers[reg].defSites.find(idx) != registers[reg].defSites.end()) continue;
+                globalRegisters.insert(reg);
+            }
+
+            const auto& exit = block->exit();
+            switch (exit->type()) {
+            case furlang::ir::instruction_t::Branch: {
+                const auto& br = dynamic_cast<const furlang::ir::branch_instruction&>(*exit);
+                blocks[br.block()].predecessors.push_back(idx);
+                blocks[idx].successors.push_back(br.block());
+            } break;
+            case furlang::ir::instruction_t::BranchCond: {
+                const auto& br = dynamic_cast<const furlang::ir::branch_cond_instruction&>(*exit);
+                blocks[br.if_block()].predecessors.push_back(idx);
+                blocks[br.else_block()].predecessors.push_back(idx);
+                blocks[idx].successors.push_back(br.if_block());
+                blocks[idx].successors.push_back(br.else_block());
+            } break;
+            default: break;
+            }
+        }
+    }
+
+    void compute_rpo() {
+        std::unordered_set<block_idx> visited;
+
+        auto dfs = [&](auto& self, block_idx block) -> void {
+            visited.insert(block);
+            for (auto succ : blocks[block].successors) {
+                if (visited.find(succ) != visited.end()) continue;
+                self(self, succ);
+            }
+            rpoOrder.push_back(block);
+        };
+
+        if (!function->blocks().empty()) dfs(dfs, 0);
+
+        std::reverse(rpoOrder.begin(), rpoOrder.end());
+        for (std::size_t i = 0; i < rpoOrder.size(); ++i) {
+            blocks[rpoOrder[i]].rpoIndex = i;
+        }
+    }
+
+    void compute_dominance() {
+        if (rpoOrder.empty()) return;
+
+        const block_idx entry = rpoOrder.front();
+        blocks[entry].idom    = entry;
+
+        bool changed = true;
+        while (changed) {
+            changed = false;
+
+            for (block_idx idx : rpoOrder) {
+                if (idx == entry) continue;
+
+                block_idx newIdom = INVALID_BLOCK;
+                bool      found   = false;
+                for (auto pred : blocks[idx].predecessors) {
+                    if (blocks[pred].idom == INVALID_BLOCK) continue;
+                    if (found) {
+                        newIdom = intersect(pred, newIdom);
+                    } else {
+                        newIdom = pred;
+                        found   = true;
+                    }
+                }
+
+                if (blocks[idx].idom != newIdom) {
+                    blocks[idx].idom = newIdom;
+                    changed          = true;
+                }
+            }
+        }
+
+        for (auto idx : rpoOrder) {
+            if (idx == entry) continue;
+            const block_idx parent = blocks[idx].idom;
+            if (parent != INVALID_BLOCK) blocks[parent].doms.push_back(idx);
+        }
+
+        for (auto idx : rpoOrder) {
+            if (blocks[idx].predecessors.size() < 2) continue;
+            for (auto cur : blocks[idx].predecessors) {
+                while (cur != blocks[idx].idom) {
+                    blocks[cur].domFrontiers.insert(idx);
+                    cur = blocks[cur].idom;
+                }
+            }
+        }
+    }
+
+    furlang::ir::function*                        function;
+    std::vector<block_idx>                        rpoOrder;
+    std::unordered_map<block_idx, block_info>     blocks;
+    std::unordered_map<register_t, register_info> registers;
+    std::unordered_set<register_t>                globalRegisters;
+private:
+    block_idx intersect(block_idx block1, block_idx block2) {
+        while (block1 != block2) {
+            while (blocks[block1].rpoIndex > blocks[block2].rpoIndex)
+                block1 = blocks[block1].idom;
+            while (blocks[block2].rpoIndex > blocks[block1].rpoIndex)
+                block2 = blocks[block2].idom;
+        }
+        return block1;
+    }
+};
+
+static void ssa_stage_rename_block(function_context&           ctx,
+    block_idx                                                  idx,
+    std::unordered_map<register_t, std::uint32_t>&             regVers,
+    std::unordered_map<register_t, std::stack<std::uint32_t>>& regVerStacks) {
+    std::unordered_map<register_t, std::uint32_t> pushed;
+
+    const auto& block = ctx.function->blocks()[idx];
+    auto        it    = block->instructions().begin();
+    for (; it != block->instructions().end(); ++it) {
+        auto& instr = *it;
+        if (instr->type() != furlang::ir::instruction_t::Phi) break;
+
+        const register_t    orig   = instr->destination().reg();
+        const std::uint32_t newVer = regVers[orig]++;
+
+        instr->destination().reg().ver = newVer;
+        regVerStacks[orig].push(newVer);
+        ++pushed[orig];
+    }
+
+    for (; it != block->instructions().end(); ++it) {
+        auto& instr = *it;
+        for (auto& operand : instr->sources()) {
+            if (operand->type() != furlang::ir::operand_t::Register) continue;
+
+            const register_t orig = operand->reg();
+            if (regVerStacks[orig].empty()) continue;
+            operand->reg().ver = regVerStacks[orig].top();
+        }
+
+        if (instr->has_destination() && instr->destination().type() == furlang::ir::operand_t::Register) {
+            const register_t    orig   = instr->destination().reg();
+            const std::uint32_t newVer = regVers[orig]++;
+
+            instr->destination().reg().ver = newVer;
+            regVerStacks[orig].push(newVer);
+            ++pushed[orig];
+        }
+    }
+
+    for (auto& operand : block->exit()->sources()) {
+        if (operand->type() != furlang::ir::operand_t::Register) continue;
+
+        const auto orig = operand->reg();
+        if (regVerStacks[orig].empty()) continue;
+        operand->reg().ver = regVerStacks[orig].top();
+    }
+
+    for (auto succIdx : ctx.blocks[idx].successors) {
+        const auto& succ = ctx.function->blocks()[succIdx];
+        for (auto& instr : succ->instructions()) {
+            if (instr->type() != furlang::ir::instruction_t::Phi) break;
+
+            auto& phi = dynamic_cast<furlang::ir::phi_instruction&>(*instr);
+            for (auto& pair : phi.labels()) {
+                if (pair.second != idx) continue;
+
+                auto orig = pair.first.reg();
+                if (auto it = regVerStacks.find(orig); it != regVerStacks.end())
+                    pair.first.reg().ver = it->second.top();
+            }
+        }
+    }
+
+    for (const auto& child : ctx.blocks[idx].doms) {
+        ssa_stage_rename_block(ctx, child, regVers, regVerStacks);
+    }
+
+    for (const auto& [reg, count] : pushed) {
+        for (std::size_t i = 0; i < count; ++i)
+            regVerStacks[reg].pop();
+    }
+}
+
+static void ssa_stage(function_context& ctx) {
+    ctx.compute_dominance();
+
+    std::vector<block_idx> worklist;
+    for (const auto& [reg, info] : ctx.registers) {
+        if (info.defSites.size() < 2 || ctx.globalRegisters.find(reg) == ctx.globalRegisters.end()) continue;
+
+        worklist.clear();
+        worklist.insert(worklist.end(), info.defSites.begin(), info.defSites.end());
+
+        std::unordered_set<block_idx> added;
+        while (!worklist.empty()) {
+            const auto idx = worklist.back();
+            worklist.pop_back();
+            for (auto frontier : ctx.blocks[idx].domFrontiers) {
+                if (added.find(frontier) != added.end()) continue;
+                added.insert(frontier);
+
+                const auto& target = ctx.function->blocks()[frontier];
+                const auto& preds  = ctx.blocks[frontier].predecessors;
+
+                auto instr = std::make_unique<furlang::ir::phi_instruction>(reg);
+                for (auto pred : preds) {
+                    instr->labels().emplace_back(furlang::ir::operand::new_reg(reg), pred);
+                }
+                target->instructions().emplace(target->instructions().begin(), std::move(instr));
+
+                if (info.defSites.find(frontier) == info.defSites.end()) worklist.push_back(frontier);
+            }
+        }
+    }
+
+    std::unordered_map<register_t, std::uint32_t>             regVers;
+    std::unordered_map<register_t, std::stack<std::uint32_t>> regVerStacks;
+    ssa_stage_rename_block(ctx, ctx.rpoOrder.front(), regVers, regVerStacks);
+}
+
+static void dessa_stage(function_context& ctx) {
+    for (block_idx idx = 0; idx < ctx.function->blocks().size(); ++idx) {
+        const auto& block  = ctx.function->blocks()[idx];
+        auto&       instrs = block->instructions();
+        for (auto it = instrs.begin(); it != instrs.end() && (*it)->type() == furlang::ir::instruction_t::Phi;
+            it       = instrs.erase(it)) {
+            auto& phi    = dynamic_cast<furlang::ir::phi_instruction&>(**it);
+            auto  dstReg = phi.destination().reg();
+            for (auto& [srcOp, label] : phi.labels()) {
+                ctx.function->blocks()[label]->instructions().push_back(
+                    std::make_unique<furlang::ir::assign_instruction>(furlang::ir::operand::new_reg(srcOp.reg()),
+                        furlang::ir::operand::new_reg(dstReg)));
+            }
+        }
+    }
+}
+
+struct sccp_lattice {
+    enum lattice_t { // NOLINT
+        Top,
+        Constant,
+        Bottom,
+    } type                 = Top;
+    std::uint64_t constant = 0;
+
+    bool operator==(const sccp_lattice& other) const {
+        return type == other.type && (type != Constant || constant == other.constant);
+    }
+
+    bool operator!=(const sccp_lattice& other) const { return !this->operator==(other); }
+};
+
+sccp_lattice sccp_stage_get_lattice(std::unordered_map<register_op, sccp_lattice>& latticeValues,
+    const furlang::ir::operand&                                                    op) {
+    if (op.type() == furlang::ir::operand_t::Integer) {
+        sccp_lattice lat;
+        lat.type     = sccp_lattice::Constant;
+        lat.constant = op.integer();
+        return lat;
+    }
+    if (op.type() == furlang::ir::operand_t::Register) {
+        auto reg = op.reg();
+        if (auto it = latticeValues.find(reg); it != latticeValues.end()) return it->second;
+        return { sccp_lattice::Top };
+    }
+    return { sccp_lattice::Bottom };
+};
+
+static void sccp_stage(function_context& ctx) {
+    using lattice = sccp_lattice;
+
+    std::unordered_map<register_op, lattice>                               latticeValues;
+    std::unordered_map<register_t, std::vector<furlang::ir::instruction*>> edges;
+    std::unordered_set<block_idx>                                          execBlocks;
+    std::set<std::pair<block_idx, block_idx>>                              execEdges;
+
+    std::queue<std::pair<block_idx, block_idx>> cfgWorklist;
+    std::queue<furlang::ir::instruction*>       ssaWorklist;
+
+    std::unordered_map<furlang::ir::instruction*, block_idx> blockMap;
+
+    for (block_idx idx = 0; idx < ctx.function->blocks().size(); ++idx) {
+        const auto& block  = ctx.function->blocks()[idx];
+        auto&       instrs = block->instructions();
+        for (auto it = instrs.begin(); it != instrs.end(); ++it) {
+            const auto& instr     = *it;
+            blockMap[instr.get()] = idx;
+            for (const auto& op : instr->sources()) {
+                if (op->type() != furlang::ir::operand_t::Register) continue;
+                edges[op->reg()].push_back(instr.get());
+            }
+        }
+
+        blockMap[block->exit().get()] = idx;
+        for (const auto& op : block->exit()->sources()) {
+            if (op->type() != furlang::ir::operand_t::Register) continue;
+            edges[op->reg()].push_back(block->exit().get());
+        }
+    }
+
+    cfgWorklist.push({ 0, 0 });
+    while (!cfgWorklist.empty() || !ssaWorklist.empty()) {
+        if (!cfgWorklist.empty()) {
+            auto edge = cfgWorklist.front();
+            cfgWorklist.pop();
+            block_idx from = edge.first;
+            block_idx to   = edge.second;
+
+            if (execEdges.count(edge) != 0) continue;
+            execEdges.insert(edge);
+
+            bool firstVisit = (execBlocks.find(to) == execBlocks.end());
+            execBlocks.insert(to);
+
+            const auto& block = ctx.function->blocks()[to];
+            if (firstVisit) {
+                for (auto& instr : block->instructions()) {
+                    ssaWorklist.push(instr.get());
+                }
+                ssaWorklist.push(block->exit().get());
+            } else {
+                for (auto& instr : block->instructions()) {
+                    if (instr->type() != furlang::ir::instruction_t::Phi) break;
+                    ssaWorklist.push(instr.get());
+                }
+            }
+        }
+
+        if (!ssaWorklist.empty()) {
+            auto* instr = ssaWorklist.front();
+            ssaWorklist.pop();
+
+            block_idx blockIdx = blockMap[instr];
+            if (execBlocks.find(blockIdx) == execBlocks.end()) continue;
+
+            lattice newLat = { lattice::Top };
+
+            switch (instr->type()) {
+            case furlang::ir::instruction_t::Phi: {
+                auto& phi = dynamic_cast<furlang::ir::phi_instruction&>(*instr);
+                for (const auto& [op, label] : phi.labels()) {
+                    if (execEdges.count({ label, blockIdx }) == 0) continue;
+                    lattice opLat = sccp_stage_get_lattice(latticeValues, op);
+                    if (opLat.type == lattice::Bottom) newLat.type = lattice::Bottom;
+                    if (opLat.type == lattice::Constant) {
+                        if (newLat.type == lattice::Top) {
+                            newLat = opLat;
+                        } else if (newLat.type == lattice::Constant && newLat.constant != opLat.constant) {
+                            newLat.type = lattice::Bottom;
+                        }
+                    }
+                }
+            } break;
+            case furlang::ir::instruction_t::Assign: {
+                newLat = sccp_stage_get_lattice(latticeValues, *instr->sources().front());
+            } break;
+            case furlang::ir::instruction_t::Add:
+            case furlang::ir::instruction_t::Sub:
+            case furlang::ir::instruction_t::Mul:
+            case furlang::ir::instruction_t::Div:
+            case furlang::ir::instruction_t::Mod:
+            case furlang::ir::instruction_t::Eq:
+            case furlang::ir::instruction_t::NotEq:
+            case furlang::ir::instruction_t::LessThan:
+            case furlang::ir::instruction_t::GreaterThan:
+            case furlang::ir::instruction_t::LessEq:
+            case furlang::ir::instruction_t::GreaterEq: {
+                lattice lhs = sccp_stage_get_lattice(latticeValues, *instr->sources()[0]);
+                lattice rhs = sccp_stage_get_lattice(latticeValues, *instr->sources()[1]);
+
+                if (lhs.type == lattice::Bottom || rhs.type == lattice::Bottom) {
+                    newLat.type = lattice::Bottom;
+                } else if (lhs.type == lattice::Constant && rhs.type == lattice::Constant) {
+                    newLat.type = lattice::Constant;
+                    switch (instr->type()) {
+                    case furlang::ir::instruction_t::Add: newLat.constant = lhs.constant + rhs.constant; break;
+                    case furlang::ir::instruction_t::Sub: newLat.constant = lhs.constant - rhs.constant; break;
+                    case furlang::ir::instruction_t::Mul: newLat.constant = lhs.constant * rhs.constant; break;
+                    case furlang::ir::instruction_t::Div: newLat.constant = lhs.constant / rhs.constant; break;
+                    case furlang::ir::instruction_t::Mod: newLat.constant = lhs.constant % rhs.constant; break;
+                    case furlang::ir::instruction_t::Eq:
+                        newLat.constant = (lhs.constant == rhs.constant) ? 1 : 0;
+                        break;
+                    case furlang::ir::instruction_t::NotEq:
+                        newLat.constant = (lhs.constant != rhs.constant) ? 1 : 0;
+                        break;
+                    case furlang::ir::instruction_t::LessThan:
+                        newLat.constant = (lhs.constant < rhs.constant) ? 1 : 0;
+                        break;
+                    case furlang::ir::instruction_t::GreaterThan:
+                        newLat.constant = (lhs.constant > rhs.constant) ? 1 : 0;
+                        break;
+                    case furlang::ir::instruction_t::LessEq:
+                        newLat.constant = (lhs.constant <= rhs.constant) ? 1 : 0;
+                        break;
+                    case furlang::ir::instruction_t::GreaterEq:
+                        newLat.constant = (lhs.constant >= rhs.constant) ? 1 : 0;
+                        break;
+                    default: throw std::runtime_error("unreachable");
+                    }
+                }
+            } break;
+            default: break;
+            }
+
+            if (instr->has_destination() && instr->destination().type() == furlang::ir::operand_t::Register) {
+                auto dst = instr->destination().reg();
+                if (!(latticeValues[dst] == newLat)) {
+                    latticeValues[dst] = newLat;
+                    for (auto* uInstr : edges[dst])
+                        ssaWorklist.push(uInstr);
+                }
+            }
+
+            if (instr == ctx.function->blocks()[blockIdx]->exit().get()) {
+                auto* exit = ctx.function->blocks()[blockIdx]->exit().get();
+                if (exit->type() == furlang::ir::instruction_t::Branch) {
+                    auto& br = dynamic_cast<furlang::ir::branch_instruction&>(*exit);
+                    cfgWorklist.push({ blockIdx, br.block() });
+                } else if (exit->type() == furlang::ir::instruction_t::BranchCond) {
+                    auto&   br   = dynamic_cast<furlang::ir::branch_cond_instruction&>(*exit);
+                    lattice cond = sccp_stage_get_lattice(latticeValues, *exit->sources()[0]);
+
+                    if (cond.type == lattice::Constant) {
+                        if (cond.constant != 0)
+                            cfgWorklist.push({ blockIdx, br.if_block() });
+                        else
+                            cfgWorklist.push({ blockIdx, br.else_block() });
+                    } else {
+                        cfgWorklist.push({ blockIdx, br.if_block() });
+                        cfgWorklist.push({ blockIdx, br.else_block() });
+                    }
+                }
+            }
+        }
+    }
+
+    for (block_idx i = 0; i < ctx.function->blocks().size(); ++i) {
+        if (execBlocks.find(i) == execBlocks.end()) {
+            ctx.function->blocks()[i]->instructions().clear();
+            continue;
+        }
+
+        const auto& block = ctx.function->blocks()[i];
+
+        for (auto& instr : block->instructions()) {
+            for (auto& op : instr->sources()) {
+                if (op->type() != furlang::ir::operand_t::Register) continue;
+                auto reg = op->reg();
+                if (latticeValues[reg].type != lattice::Constant) continue;
+                *op = furlang::ir::operand::new_integer(latticeValues[reg].constant);
+            }
+        }
+
+        auto* exit = block->exit().get();
+        if (exit->type() != furlang::ir::instruction_t::BranchCond) continue;
+        auto&   br   = dynamic_cast<furlang::ir::branch_cond_instruction&>(*exit);
+        lattice cond = sccp_stage_get_lattice(latticeValues, *exit->sources()[0]);
+        if (cond.type != lattice::Constant) continue;
+        block_idx target = (cond.constant != 0) ? br.if_block() : br.else_block();
+        block->exit()    = std::make_unique<furlang::ir::branch_instruction>(target);
+    }
+}
+
+static void adce_stage(function_context& ctx) {
+    std::unordered_map<register_op, furlang::ir::instruction*> defMap;
+    std::unordered_set<furlang::ir::instruction*>              alive;
+    std::queue<furlang::ir::instruction*>                      worklist;
+
+    for (block_idx blockIdx = 0; blockIdx < ctx.function->blocks().size(); ++blockIdx) {
+        const auto& block = ctx.function->blocks()[blockIdx];
+
+        for (auto& instr : block->instructions()) {
+            if (instr->has_destination() && instr->destination().type() == furlang::ir::operand_t::Register) {
+                defMap[instr->destination().reg()] = instr.get();
+            }
+            if (instr->type() == furlang::ir::instruction_t::Call) {
+                // TODO: Check if the function has side effects
+                if (alive.insert(instr.get()).second) worklist.push(instr.get());
+            }
+        }
+
+        auto* exit = block->exit().get();
+        alive.insert(exit);
+        worklist.push(exit);
+    }
+
+    while (!worklist.empty()) {
+        const auto* instr = worklist.front();
+        worklist.pop();
+
+        for (const auto& op : instr->sources()) {
+            if (op->type() != furlang::ir::operand_t::Register) continue;
+            auto src = op->reg();
+
+            if (defMap.find(src) == defMap.end()) continue;
+            auto* defInstr = defMap[src];
+            if (alive.insert(defInstr).second) {
+                worklist.push(defInstr);
+            }
+        }
+    }
+
+    for (block_idx blockIdx = 0; blockIdx < ctx.function->blocks().size(); ++blockIdx) {
+        const auto& block  = ctx.function->blocks()[blockIdx];
+        auto&       instrs = block->instructions();
+
+        auto it = instrs.begin();
+        while (it != instrs.end()) {
+            it = (alive.find(it->get()) != alive.end()) ? it + 1 : instrs.erase(it);
+        }
+    }
+}
+
+void post_process::process(furlang::ir::mod& mod) {
+    for (const auto& func : mod.functions()) {
+        if (!func || func->blocks().empty()) continue;
+        function_context ctx{ func.get() };
+
+        for (const auto& stage : m_stages) {
+            switch (stage) {
+            case Ssa: ssa_stage(ctx); break;
+            case Sccp: sccp_stage(ctx); break;
+            case Adce: adce_stage(ctx); break;
+            case DeSsa: dessa_stage(ctx); break;
+            }
+        }
+    }
+}
+
+} // namespace furc::front

furc/src/main.cpp

@@ -1,28 +1,33 @@
 #ifndef LIBFURC
 
 #include "furc/ast/program.hpp"
+#include "furc/back/furvm.hpp"
 #include "furc/front/ir_generator.hpp"
 #include "furc/front/parser.hpp"
+#include "furc/front/post_process.hpp"
+#include "furlang/arena.hpp"
 
+#include <fstream>
+#include <furvm/furvm.hpp>
 #include <iostream>
 
 int main(void) {
     try {
         std::string               programStr = R"(
-    func main() {
-        x = 5;
-        x -= 3;
-        if (x < 3) {
-            y = x * 2;
-            w = y;
-        } else {
-            y = x - 3;
+    private native func print(value: int32);
+
+    func main() -> int32 {
+        x = 0;
+        y = 10;
+        z = 1;
+        while (x < y) {
+            x = x + z;
         }
-        w = x - y;
-        z = x + y;
+        print(sizeof x);
     }
     )";
-        furc::front::parser       parser("<TEMP>", programStr);
+        furlang::arena            arena{};
+        furc::front::parser       parser(arena, "<TEMP>", programStr);
         furc::front::ir_generator generator;
 
         auto programResult = parser.parse();
@@ -33,9 +38,17 @@ int main(void) {
         const auto& program = *programResult;
         program->accept(generator);
 
-        auto module = std::move(generator.move_module());
+        auto mod = std::move(generator.move_module());
+
+        furc::front::post_process postProcess;
+        postProcess.push_stage(furc::front::post_process::Ssa);
+        postProcess.push_stage(furc::front::post_process::Sccp);
+        postProcess.push_stage(furc::front::post_process::Adce);
+        postProcess.push_stage(furc::front::post_process::DeSsa);
+        postProcess.process(mod);
+
         std::cout << "Generated IR:\n";
-        for (const auto& function : module.functions()) {
+        for (const auto& function : mod.functions()) {
             std::cout << function->name() << ":\n";
             furlang::ir::block_index blockIndex = 0;
             for (const auto& block : function->blocks()) {
@@ -47,6 +60,25 @@ int main(void) {
             }
         }
 
+        auto context  = std::make_shared<furvm::context>();
+        auto furvmMod = context->emplace("main", furc::back::furvm_generator::generate(mod));
+
+        std::ofstream file("./a.fmod", std::ios::binary);
+        furvmMod->serialize(file);
+        file.close();
+
+        furvmMod->set_native_function("print",
+            [](furvm::executor& executor) { std::cout << executor.load_thing(0)->integer() << '\n'; });
+
+        furvm::executor_h executor = context->emplace_executor(context);
+        executor->push_frame(furvmMod, *furvmMod->function_at("main", furvm::function_sig{}));
+
+        std::cout << "--- Interpreting:\n";
+
+        while ((executor->flags() & furvm::executor_flags::Done) != furvm::executor_flags::Done) {
+            executor->step();
+        }
+
         return 0;
     } catch (...) {
         std::cerr << "Caught an exception in main!\n";

furlang/include/furlang/arena.hpp

@@ -106,6 +106,55 @@ private:
     region*     m_tail = nullptr;
 };
 
+template <typename T>
+class arena_allocator {
+    template <typename>
+    friend class arena_allocator;
+public:
+    using value_type = T;
+public:
+    explicit arena_allocator(arena& arena) noexcept
+      : m_arena(&arena) {}
+
+    template <typename U>
+    arena_allocator(const arena_allocator<U>& other) noexcept
+      : m_arena(other.m_arena) {}
+
+    template <typename U>
+    arena_allocator& operator=(const arena_allocator<U>& other) noexcept {
+        if (this == &other) return *this;
+        m_arena = other.m_arena;
+        return *this;
+    }
+
+    template <typename U>
+    arena_allocator(arena_allocator<U>&& other) noexcept
+      : m_arena(std::move(other.m_arena)) {}
+
+    template <typename U>
+    arena_allocator& operator=(arena_allocator<U>&& other) noexcept {
+        if (this == &other) return *this;
+        m_arena = std::move(other.m_arena);
+        return *this;
+    }
+public:
+    [[nodiscard]] T* allocate(std::size_t count = 1) { return m_arena->allocate<T>(count); }
+
+    void deallocate(T* ptr, std::size_t count) noexcept {}
+public:
+    template <typename U>
+    bool operator==(const arena_allocator<U>& other) const noexcept {
+        return m_arena == other.m_arena;
+    }
+
+    template <typename U>
+    bool operator!=(const arena_allocator<U>& other) const noexcept {
+        return m_arena != other.m_arena;
+    }
+private:
+    arena* m_arena;
+};
+
 } // namespace furlang
 
 #endif // FURLANG_ARENA_HPP

furlang/include/furlang/ir/function.hpp

@@ -3,12 +3,25 @@
 
 #include "furlang/ir/block.hpp"
 
+#include <cstdint>
 #include <memory>
+#include <type_traits>
 #include <vector>
 
 namespace furlang {
 namespace ir {
 
+enum class function_t : std::uint8_t {
+    Normal = 0,
+    Import,
+    Native,
+};
+
+enum class function_access_t : std::uint8_t {
+    Public = 0,
+    Private,
+};
+
 /**
  * @brief IR function.
  *
@@ -22,18 +35,11 @@ public:
     /**
      * @brief Construct a new IR function.
      *
-     * @param name Name to copy.
+     * @param name Name to forward.
      */
-    function(const std::string& name)
-      : m_name(name) {}
-
-    /**
-     * @brief Construct a new IR function.
-     *
-     * @param name Name to move.
-     */
-    function(std::string&& name)
-      : m_name(std::move(name)) {}
+    template <typename StringFwd, typename = std::enable_if_t<std::is_constructible_v<std::string, StringFwd>>>
+    function(StringFwd&& name, function_access_t access, std::uint32_t paramCount, function_t type = function_t::Normal)
+      : m_name(std::forward<StringFwd>(name)), m_access(access), m_paramCount(paramCount), m_type(type) {}
 public:
     /**
      * @brief Returns this function's name.
@@ -42,6 +48,27 @@ public:
      */
     const std::string& name() const { return m_name; }
 
+    /**
+     * @brief Returns the function's access.
+     *
+     * @return The access.
+     */
+    function_access_t access() const { return m_access; }
+
+    /**
+     * @brief Returns this function's parameter count.
+     *
+     * @return The parameter count.
+     */
+    std::uint32_t param_count() const { return m_paramCount; }
+
+    /**
+     * @brief Returns this function's type.
+     *
+     * @return The type.
+     */
+    function_t type() const { return m_type; }
+
     /**
      * @brief Pushes and returns a new IR block.
      *
@@ -57,6 +84,9 @@ public:
     const std::vector<value_type>& blocks() const { return m_blocks; }
 private:
     std::string             m_name;
+    function_access_t       m_access;
+    function_t              m_type;
+    std::uint32_t           m_paramCount;
     std::vector<value_type> m_blocks;
 };
 

furlang/include/furlang/ir/instruction.hpp

@@ -6,6 +6,10 @@
 #include <cstdint>
 #include <optional>
 #include <ostream>
+#include <stdexcept>
+#include <string>
+#include <utility>
+#include <vector>
 
 namespace furlang {
 namespace ir {
@@ -14,15 +18,53 @@ namespace ir {
  * @brief IR instruction type.
  */
 enum class instruction_t {
-    Alloca,     /**< Unused */
-    Assign,     /**< Assign */
-    BinaryOp,   /**< Binary operation */
-    Call,       /**< Call */
-    Branch,     /**< Branch */
-    BranchCond, /**< Conditional branch */
-    Return,     /**< Return */
+    Alloca,      /**< Unused */
+    Assign,      /**< Assign */
+    Add,         /**< Addition */
+    Sub,         /**< Subtraction */
+    Mul,         /**< Multiplication */
+    Div,         /**< Division */
+    Mod,         /**< Modulo */
+    Eq,          /**< Equal */
+    NotEq,       /**< Not equal */
+    LessThan,    /**< Less than */
+    GreaterThan, /**< Greater than */
+    LessEq,      /**< Less or equal */
+    GreaterEq,   /**< Greater or equal */
+    Pointerof,   /**< Pointerof */
+    Sizeof,      /**< Sizeof */
+    Call,        /**< Call */
+    Branch,      /**< Branch */
+    BranchCond,  /**< Conditional branch */
+    Return,      /**< Return */
+    Phi,         /**< Phi function */
 };
 
+static inline std::ostream& operator<<(std::ostream& os, instruction_t type) {
+    switch (type) {
+    case instruction_t::Alloca: return os << "alloca";
+    case instruction_t::Assign: return os << "assign";
+    case instruction_t::Add: return os << "add";
+    case instruction_t::Sub: return os << "sub";
+    case instruction_t::Mul: return os << "mul";
+    case instruction_t::Div: return os << "div";
+    case instruction_t::Mod: return os << "mod";
+    case instruction_t::Eq: return os << "eq";
+    case instruction_t::NotEq: return os << "notEq";
+    case instruction_t::LessThan: return os << "lessThan";
+    case instruction_t::GreaterThan: return os << "greaterThan";
+    case instruction_t::LessEq: return os << "lessEq";
+    case instruction_t::GreaterEq: return os << "greaterEq";
+    case instruction_t::Pointerof: return os << "pointerof";
+    case instruction_t::Sizeof: return os << "sizeof";
+    case instruction_t::Call: return os << "call";
+    case instruction_t::Branch: return os << "branch";
+    case instruction_t::BranchCond: return os << "branchCond";
+    case instruction_t::Return: return os << "return";
+    case instruction_t::Phi: return os << "phi";
+    }
+}
+
 /**
  * @brief Checks if an instruction type exits.
  *
@@ -66,6 +108,41 @@ public:
      * @return The type.
      */
     virtual instruction_t type() const = 0;
+
+    /**
+     * @brief Returns whether this instruction has a destination operand.
+     *
+     * @return true if this instruction has the destination operand.
+     */
+    virtual bool has_destination() const { return false; }
+
+    /**
+     * @brief Returns destination operand of this instruction.
+     *
+     * @return The destination operand.
+     */
+    virtual operand& destination() { throw std::runtime_error("instruction type mismatch"); }
+
+    /**
+     * @brief Returns destination operand of this instruction.
+     *
+     * @return The destination operand.
+     */
+    virtual const operand& destination() const { throw std::runtime_error("instruction type mismatch"); }
+
+    /**
+     * @brief Returns a list of source operands of this instruction.
+     *
+     * @return The list of source operands.
+     */
+    virtual std::vector<operand*> sources() { return {}; }
+
+    /**
+     * @brief Returns a list of source operands of this instruction.
+     *
+     * @return The list of source operands.
+     */
+    virtual std::vector<const operand*> sources() const { return {}; }
 public:
     /**
      * @brief Prints an instruction to an output stream.
@@ -158,18 +235,39 @@ public:
     instruction_t type() const override { return instruction_t::Assign; }
 
     /**
-     * @brief Returns this instruction's source.
+     * @brief Returns whether this instruction has a destination operand.
      *
-     * @return The source.
+     * @return true
      */
-    const operand& source() const { return m_source; }
+    bool has_destination() const override { return true; }
 
     /**
      * @brief Returns this instruction's destination.
      *
      * @return The destination.
      */
-    const operand& destination() const { return m_destination; }
+    operand& destination() override { return m_destination; }
+
+    /**
+     * @brief Returns this instruction's destination.
+     *
+     * @return The destination.
+     */
+    const operand& destination() const override { return m_destination; }
+
+    /**
+     * @brief Returns a list of this instruction's source operands.
+     *
+     * @return The list of source operands.
+     */
+    std::vector<operand*> sources() override { return { &m_source }; }
+
+    /**
+     * @brief Returns a list of this instruction's source operands.
+     *
+     * @return The list of source operands.
+     */
+    std::vector<const operand*> sources() const override { return { &m_source }; }
 private:
     operand m_source;
     operand m_destination;
@@ -180,85 +278,122 @@ protected:
 };
 
 /**
- * @brief Binary operation instruction type
+ * @brief Generic unary instruction
  */
-enum class binary_op_instruction_t {
-    Add, /**< Addition */
-    Sub, /**< Subtraction */
-    Mul, /**< Multiplication */
-    Div, /**< Division */
-    Mod, /**< Modulo */
+class unary_instruction final : public instruction {
+public:
+    /**
+     * @brief Construct a new unary instruction.
+     *
+     * @param type Instruction type.
+     * @param src Source operand.
+     * @param dst Destination operand.
+     */
+    unary_instruction(instruction_t type, operand&& src, operand&& dst)
+      : m_type(type), m_src(std::move(src)), m_dst(std::move(dst)) {}
 
-    Eq,          /**< Equal */
-    NotEq,       /**< Not equal */
-    LessThan,    /**< Less than */
-    GreaterThan, /**< Greater than */
-    LessEq,      /**< Less or equal */
-    GreaterEq,   /**< Greater or equal */
+    ~unary_instruction() override = default;
+
+    /**
+     * @brief Move constructor
+     */
+    unary_instruction(unary_instruction&&) = default;
+
+    /**
+     * @brief Move constructor
+     */
+    unary_instruction& operator=(unary_instruction&&) = default;
+
+    unary_instruction(const unary_instruction&) = delete;
+
+    unary_instruction& operator=(const unary_instruction&) = delete;
+public:
+    /**
+     * @brief Returns this instruction's type.
+     *
+     * @return The instruction type.
+     */
+    instruction_t type() const override { return m_type; }
+
+    bool has_destination() const override { return true; }
+
+    operand& destination() override { return m_dst; }
+
+    const operand& destination() const override { return m_dst; }
+
+    std::vector<operand*> sources() override { return { &m_src }; }
+
+    std::vector<const operand*> sources() const override { return { &m_src }; }
+
+    /**
+     * @brief Returns this instruction's source operand.
+     *
+     * @return The operand.
+     */
+    const operand& src() const { return m_src; }
+
+    /**
+     * @brief Returns this instruction's destination operand.
+     *
+     * @return The operand.
+     */
+    const operand& dst() const { return m_dst; }
+private:
+    instruction_t m_type;
+    operand       m_src;
+    operand       m_dst;
+protected:
+    std::ostream& print(std::ostream& os) const override { return os << m_dst << " = " << m_type << ' ' << m_src; }
 };
 
-static inline std::ostream& operator<<(std::ostream& os, binary_op_instruction_t type) {
-    switch (type) {
-    case binary_op_instruction_t::Add: return os << '+';
-    case binary_op_instruction_t::Sub: return os << '-';
-    case binary_op_instruction_t::Mul: return os << '*';
-    case binary_op_instruction_t::Div: return os << '/';
-    case binary_op_instruction_t::Mod: return os << '%';
-    case binary_op_instruction_t::Eq: return os << "==";
-    case binary_op_instruction_t::NotEq: return os << "!=";
-    case binary_op_instruction_t::LessThan: return os << '<';
-    case binary_op_instruction_t::GreaterThan: return os << '>';
-    case binary_op_instruction_t::LessEq: return os << "<=";
-    case binary_op_instruction_t::GreaterEq: return os << ">=";
-    }
-    return os;
-}
-
 /**
- * @brief Binary operation instruction
+ * @brief Generic binary instruction
  */
-class binary_op_instruction final : public instruction {
+class binary_instruction final : public instruction {
 public:
     /**
      * @brief Construct a new binary operation instruction.
      *
-     * @param type Operation type.
+     * @param type Instruction type.
      * @param lhs Left-hand-side operand.
      * @param rhs Right-hand-side operand.
      * @param dst Destination operand.
      */
-    binary_op_instruction(binary_op_instruction_t type, operand&& lhs, operand&& rhs, operand&& dst)
+    binary_instruction(instruction_t type, operand&& lhs, operand&& rhs, operand&& dst)
       : m_type(type), m_lhs(std::move(lhs)), m_rhs(std::move(rhs)), m_dst(std::move(dst)) {}
 
-    ~binary_op_instruction() override = default;
+    ~binary_instruction() override = default;
 
     /**
      * @brief Move constructor
      */
-    binary_op_instruction(binary_op_instruction&&) = default;
+    binary_instruction(binary_instruction&&) = default;
 
     /**
      * @brief Move constructor
      */
-    binary_op_instruction& operator=(binary_op_instruction&&) = default;
+    binary_instruction& operator=(binary_instruction&&) = default;
 
-    binary_op_instruction(const binary_op_instruction&) = delete;
+    binary_instruction(const binary_instruction&) = delete;
 
-    binary_op_instruction& operator=(const binary_op_instruction&) = delete;
+    binary_instruction& operator=(const binary_instruction&) = delete;
 public:
     /**
      * @brief Returns this instruction's type.
      *
      * @return instruction_t::BinaryOp.
      */
-    instruction_t type() const override { return instruction_t::BinaryOp; }
+    instruction_t type() const override { return m_type; }
 
-    /**
-     * @brief Returns this instruction's operation type.
-     *
-     * @return The operation type.
-     */
-    binary_op_instruction_t op_type() const { return m_type; }
+    bool has_destination() const override { return true; }
+
+    operand& destination() override { return m_dst; }
+
+    const operand& destination() const override { return m_dst; }
+
+    std::vector<operand*> sources() override { return { &m_lhs, &m_rhs }; }
+
+    std::vector<const operand*> sources() const override { return { &m_lhs, &m_rhs }; }
 
     /**
      * @brief Returns this instruction's left-hand-side operand.
@@ -281,13 +416,13 @@ public:
      */
     const operand& dst() const { return m_dst; }
 private:
-    binary_op_instruction_t m_type;
-    operand                 m_lhs /**< Left-hand-side operand */;
-    operand                 m_rhs /**< Right-hand-side operand */;
-    operand                 m_dst /**< Destination operand */;
+    instruction_t m_type;
+    operand       m_lhs /**< Left-hand-side operand */;
+    operand       m_rhs /**< Right-hand-side operand */;
+    operand       m_dst /**< Destination operand */;
 protected:
     std::ostream& print(std::ostream& os) const override {
-        return os << "binop(" << m_type << ") " << m_lhs << ", " << m_rhs << ", " << m_dst;
+        return os << m_dst << " = " << m_lhs << ' ' << m_type << ' ' << m_rhs;
     }
 };
 
@@ -374,6 +509,9 @@ public:
 public:
     instruction_t type() const override { return instruction_t::BranchCond; }
 
+    std::vector<operand*>       sources() override { return { &m_condition }; }
+    std::vector<const operand*> sources() const override { return { &m_condition }; }
+
     /**
      * @brief Returns this instruction's condition operand.
      *
@@ -442,6 +580,16 @@ public:
      */
     instruction_t type() const override { return instruction_t::Return; }
 
+    std::vector<operand*> sources() override {
+        if (m_value.has_value()) return { &*m_value };
+        return {};
+    }
+
+    std::vector<const operand*> sources() const override {
+        if (m_value.has_value()) return { &*m_value };
+        return {};
+    }
+
     /**
      * @brief Returns this instruction's return value operand.
      *
@@ -458,6 +606,162 @@ protected:
     }
 };
 
+/**
+ * @brief Phi instruction
+ *
+ * Used to implement the phi node in the SSA graph.
+ */
+class phi_instruction final : public instruction {
+public:
+    phi_instruction(register_operand dst)
+      : m_dst(operand::new_reg(dst)) {}
+
+    ~phi_instruction() override = default;
+
+    /**
+     * @brief Move constructor.
+     */
+    phi_instruction(phi_instruction&&) noexcept = default;
+
+    /**
+     * @brief Move constructor.
+     */
+    phi_instruction& operator=(phi_instruction&&) noexcept = default;
+
+    phi_instruction(const phi_instruction&) = delete;
+
+    phi_instruction& operator=(const phi_instruction&) = delete;
+public:
+    /**
+     * @brief Returns this instruction's type.
+     *
+     * @return instruction_t::Phi.
+     */
+    instruction_t type() const override { return instruction_t::Phi; }
+
+    bool has_destination() const override { return true; }
+
+    /**
+     * @brief Returns this instruction's destination register.
+     *
+     * @return The register.
+     */
+    operand& destination() override { return m_dst; }
+
+    /**
+     * @brief Returns this instruction's destination register.
+     *
+     * @return The register.
+     */
+    const operand& destination() const override { return m_dst; }
+
+    std::vector<const operand*> sources() const override {
+        std::vector<const operand*> srcs;
+        srcs.reserve(m_labels.size());
+        for (const auto& [op, _block] : m_labels)
+            srcs.push_back(&op);
+        return srcs;
+    }
+
+    /**
+     * @brief Returns this instruction's labels.
+     *
+     * @return The labels.
+     */
+    std::vector<std::pair<operand, block_index>>& labels() { return m_labels; }
+
+    /**
+     * @brief Returns this instruction's labels.
+     *
+     * @return The labels.
+     */
+    const std::vector<std::pair<operand, block_index>>& labels() const { return m_labels; }
+private:
+    operand                                      m_dst;
+    std::vector<std::pair<operand, block_index>> m_labels;
+protected:
+    std::ostream& print(std::ostream& os) const override {
+        os << m_dst << " = phi";
+        bool first = true;
+        for (const auto& pair : m_labels) {
+            if (!first) os << ',';
+            first = false;
+            os << ' ' << pair.second << ": " << pair.first;
+        }
+        return os;
+    }
+};
+
+/**
+ * @brief Function call instruction.
+ */
+class call_instruction final : public instruction {
+public:
+    template <typename NameFwd, typename ArgsFwd>
+    call_instruction(NameFwd&& name, operand&& dst, ArgsFwd&& args)
+      : m_name(std::forward<NameFwd>(name)), m_dst(std::move(dst)), m_args(std::forward<ArgsFwd>(args)) {}
+
+    ~call_instruction() override = default;
+
+    call_instruction(call_instruction&&) noexcept            = default;
+    call_instruction& operator=(call_instruction&&) noexcept = default;
+    call_instruction(const call_instruction&)                = delete;
+    call_instruction& operator=(const call_instruction&)     = delete;
+public:
+    /**
+     * @brief Returns this instruction's type.
+     *
+     * @return instruction_t::Call.
+     */
+    instruction_t type() const override { return instruction_t::Call; }
+
+    bool has_destination() const override { return true; }
+
+    /**
+     * @brief Returns this instruction's destination register.
+     *
+     * @return The register.
+     */
+    operand& destination() override { return m_dst; }
+
+    /**
+     * @brief Returns this instruction's destination register.
+     *
+     * @return The register.
+     */
+    const operand& destination() const override { return m_dst; }
+
+    std::vector<const operand*> sources() const override {
+        std::vector<const operand*> srcs;
+        srcs.reserve(m_args.size());
+        for (const auto& op : m_args)
+            srcs.push_back(&op);
+        return srcs;
+    }
+
+    /**
+     * @brief Returns this instruction's callee name.
+     *
+     * @return The name.
+     */
+    const std::string& name() const { return m_name; }
+private:
+    std::string          m_name;
+    operand              m_dst;
+    std::vector<operand> m_args;
+protected:
+    std::ostream& print(std::ostream& os) const override {
+        os << "call " << m_name << '(';
+        bool first = true;
+        for (const auto& op : m_args) {
+            if (!first) os << ", ";
+            first = false;
+            os << op;
+        }
+        return os << ") = " << m_dst;
+    }
+};
+
 } // namespace ir
 } // namespace furlang
 

furlang/include/furlang/ir/module.hpp

@@ -12,11 +12,11 @@ namespace ir {
 /**
  * @brief IR module
  */
-class module {
+class mod {
 public:
     using value_type = std::unique_ptr<function>; /**< Value type. */
 public:
-    module() = default;
+    mod() = default;
 public:
     /**
      * @brief Pushes and returns a new IR function.

furlang/include/furlang/ir/operand.hpp

@@ -19,11 +19,37 @@ enum class operand_t {
     String,   /**< String */
 };
 
+/**
+ * @brief Alias to a register type.
+ */
+using register_t = std::uint32_t;
+
 /**
  * @brief Register operand alias.
  * @see operand_t::Register
  */
-using register_operand = std::uint32_t;
+struct register_operand {
+    register_t    reg = 0;
+    std::uint32_t ver = 0;
+
+    register_operand() = default;
+
+    register_operand(register_t reg)
+      : reg(reg) {}
+
+    register_operand(register_t reg, std::uint32_t ver)
+      : reg(reg), ver(ver) {}
+
+    operator std::uint32_t&() { return reg; }
+    operator const std::uint32_t&() const { return reg; }
+
+    friend std::ostream& operator<<(std::ostream& os, const register_operand& op) {
+        return os << op.reg << '_' << op.ver;
+    }
+
+    bool operator==(const register_operand& rhs) const { return reg == rhs.reg && ver == rhs.ver; }
+};
+
 /**
  * @brief Variable operand alias.
  * @see operand_t::Variable
@@ -102,6 +128,19 @@ public:
     operand(const operand&)            = delete;
     operand& operator=(const operand&) = delete;
 public:
+    /**
+     * @brief Construct a new register operand.
+     *
+     * @param value Value of the new register operand.
+     * @return The register operand.
+     */
+    static operand new_reg(register_t value) {
+        operand operand;
+        operand.m_type      = operand_t::Register;
+        operand.m_value.reg = { value, 0 };
+        return operand;
+    }
+
     /**
      * @brief Construct a new register operand.
      *
@@ -163,6 +202,13 @@ public:
      */
     operand_t type() const { return m_type; }
 
+    /**
+     * @brief Returns this operand's register value.
+     *
+     * @return The register value.
+     */
+    register_operand& reg() { return m_value.reg; }
+
     /**
      * @brief Returns this operand's register value.
      *
@@ -228,4 +274,17 @@ private:
 } // namespace ir
 } // namespace furlang
 
+namespace std {
+
+template <>
+struct hash<furlang::ir::register_operand> {
+    std::size_t operator()(const furlang::ir::register_operand& op) const noexcept {
+        std::size_t h1 = std::hash<decltype(op.reg)>{}(op.reg);
+        std::size_t h2 = std::hash<std::uint32_t>{}(op.ver);
+        return h1 ^ (h2 + 0x9e3779b9 + (h1 << 6) + (h1 >> 2));
+    }
+};
+
+} // namespace std
+
 #endif // FURLANG_IR_OPERAND_HPP

furlang/include/furlang/utility/hash.hpp

@@ -0,0 +1,47 @@
+#ifndef FURLANG_UTILITY_HASH_HPP
+#define FURLANG_UTILITY_HASH_HPP
+
+#include <cstddef>
+#include <functional>
+
+namespace furlang {
+namespace utility {
+
+// Source - https://stackoverflow.com/a/27952689
+// Posted by Yakk - Adam Nevraumont, modified by community. See post 'Timeline' for change history
+// Retrieved 2026-07-07, License - CC BY-SA 4.0
+static inline std::size_t hash_combine(std::size_t lhs, std::size_t rhs) {
+    if constexpr (sizeof(std::size_t) >= 8) {
+        lhs ^= rhs + 0x517cc1b727220a95 + (lhs << 6) + (lhs >> 2);
+    } else {
+        lhs ^= rhs + 0x9e3779b9 + (lhs << 6) + (lhs >> 2);
+    }
+
+    return lhs;
+}
+
+// Source - https://stackoverflow.com/a/20602159
+// Posted by Casey, modified by community. See post 'Timeline' for change history
+// Retrieved 2026-07-07, License - CC BY-SA 3.0
+template <typename T, typename U, typename FirstHash = std::hash<T>, typename SecondHash = std::hash<U>>
+struct pair_hash {
+    std::size_t operator()(const std::pair<T, U>& pair) const {
+        return hash_combine(FirstHash()(pair.first), SecondHash()(pair.second));
+    }
+};
+
+template <typename T, typename Hash = std::hash<T>>
+struct vector_hash {
+    std::size_t operator()(const std::vector<T>& vec) const {
+        std::size_t seed = 0;
+        for (const auto& element : vec) {
+            hash_combine(seed, Hash()(element));
+        }
+        return seed;
+    }
+};
+
+} // namespace utility
+} // namespace furlang
+
+#endif // FURLANG_UTILITY_HASH_HPP

furvm/include/furvm/constant.hpp

@@ -1,49 +1,13 @@
 #ifndef FURVM_CONSTANT_HPP
 #define FURVM_CONSTANT_HPP
 
+#include "furvm/exceptions.hpp"
 #include "furvm/fwd.hpp"
 
-#include <exception>
 #include <string_view>
 
 namespace furvm {
 
-/**
- * @brief Bad constant access exception.
- */
-class bad_constant_access : public std::exception {
-public:
-    bad_constant_access()           = default;
-    ~bad_constant_access() override = default;
-
-    /**
-     * @brief Move constructor.
-     */
-    bad_constant_access(bad_constant_access&&) noexcept = default;
-
-    /**
-     * @brief Move constructor.
-     */
-    bad_constant_access& operator=(bad_constant_access&&) noexcept = default;
-
-    /**
-     * @brief Copy constructor.
-     */
-    bad_constant_access(const bad_constant_access&) = default;
-
-    /**
-     * @brief Copy constructor.
-     */
-    bad_constant_access& operator=(const bad_constant_access&) = default;
-public:
-    /**
-     * @brief Returns a C-style string describing the cause of the error.
-     *
-     * @return The cause of the error.
-     */
-    const char* what() const noexcept override { return "bad constant access"; }
-};
-
 enum class constant_t : std::uint8_t {
     String, /**< String constant. */
 };

furvm/include/furvm/context.hpp

@@ -2,21 +2,28 @@
 #define FURVM_CONTEXT_HPP
 
 #include "furlang/arena.hpp"
+#include "furvm/executor.hpp"
 #include "furvm/fwd.hpp"
-#include "furvm/module.hpp"
+#include "furvm/handle.hpp"
+#include "furvm/module.hpp" // IWYU pragma: keep
+#include "furvm/thing.hpp"  // IWYU pragma: keep
+#include "furvm/thing_allocator.hpp"
 
-#include <queue>
-#include <type_traits>
-#include <vector>
+#include <cstddef>
+#include <utility>
 
 namespace furvm {
 
-class context {
+class context : public handle_container<mod_h> {
 public:
     friend class executor;
-    friend class thing;
 public:
-    context();
+    /**
+     * @brief Constructs a context.
+     */
+    context()
+      : m_thingAllocator(m_thingArena) {}
+
     ~context() = default;
 
     /**
@@ -33,79 +40,101 @@ public:
     context& operator=(const context&) = delete;
 public:
     /**
-     * @brief Adds a module to this context.
+     * @brief Emplaces an executor in the context.
      *
-     * @param args Arguments to forward to module's constructor.
-     * @return An index to the emplaced module.
+     * @param args Arguments forwarded to executor's constructor.
+     * @return A handle to the emplaced executor.
      */
-    template <typename... Args, typename = std::enable_if_t<std::is_constructible_v<mod, module_handle, Args...>>>
-    constexpr const auto& emplace(Args&&... args) {
-        module_handle id = static_cast<module_handle>(m_modules.size());
-        return m_modules.emplace_back(std::make_unique<mod>(id, std::forward<Args>(args)...));
+    template <typename... Args>
+    auto emplace_executor(Args&&... args) {
+        return m_executors.emplace_back(std::forward<Args>(args)...);
     }
 
     /**
-     * @brief Erases a module from this context.
+     * @brief Returns an executor from the context.
      *
-     * @param index Index to the module.
-     * @return Old value.
+     * @param args Id of the executor.
+     * @return A handle to the executor.
      */
-    mod_p erase(module_handle index) {
-        if (index >= m_modules.size()) return nullptr;
-        return std::move(m_modules[index]);
+    template <typename... Args>
+    auto executor_at(Args&&... args) {
+        return m_executors.at(std::forward<Args>(args)...);
     }
 
     /**
-     * @brief Returns a module of this context.
+     * @brief Returns an executor from the context.
      *
-     * @param index Position of the module.
-     * @return The module.
+     * @param args Id of the executor.
+     * @return A handle to the executor.
      */
-    constexpr mod_p& operator[](module_handle index) { return m_modules[index]; }
+    template <typename... Args>
+    auto executor_at(Args&&... args) const {
+        return m_executors.at(std::forward<Args>(args)...);
+    }
 
     /**
-     * @brief Returns a module of this context.
+     * @brief Erases an executor from the context.
      *
-     * @param index Position of the module.
-     * @return The module.
+     * @param args Id of the executor.
      */
-    constexpr const mod_p& operator[](module_handle index) const { return m_modules[index]; }
-
-    /**
-     * @brief Returns a module of this context.
-     *
-     * @param index Position of the module.
-     * @return The module.
-     */
-    constexpr mod_p& at(module_handle index) { return m_modules.at(index); }
-
-    /**
-     * @brief Returns a module of this context.
-     *
-     * @param index Position of the module.
-     * @return The module.
-     */
-    constexpr const mod_p& at(module_handle index) const { return m_modules.at(index); }
-
-    /**
-     * @brief Returns how many does this context have modules.
-     *
-     * @return The module count.
-     */
-    constexpr size_t size() const { return m_modules.size(); }
+    template <typename... Args>
+    void erase_executor(Args&&... args) {
+        m_executors.erase(std::forward<Args>(args)...);
+    }
 public:
-    /**
-     * @brief Removes unreferenced things from the thing list.
-     */
-    void collect();
-private:
-    std::vector<mod_p>      m_modules;
-    std::vector<thing_p>    m_things;
-    std::vector<executor_p> m_executors;
+    template <typename... Args>
+    auto emplace_thing(Args&&... args) {
+        return m_things.emplace_back(std::forward<Args>(args)...);
+    }
 
-    std::queue<thing_handle> m_deadThings;
-    std::vector<void*>       m_deadThingData;
-    furlang::arena           m_thingArena;
+    /**
+     * @brief Returns a thing from the context.
+     *
+     * @param args Id of the thing.
+     * @return A handle to the thing.
+     */
+    template <typename... Args>
+    auto thing_at(Args&&... args) {
+        return m_things.at(std::forward<Args>(args)...);
+    }
+
+    /**
+     * @brief Returns a thing from the context.
+     *
+     * @param args Id of the thing.
+     * @return A handle to the thing.
+     */
+    template <typename... Args>
+    auto thing_at(Args&&... args) const {
+        return m_things.at(std::forward<Args>(args)...);
+    }
+
+    /**
+     * @brief Erases a thing from the context.
+     *
+     * @param args Id of the thing.
+     */
+    template <typename... Args>
+    void erase_thing(Args&&... args) {
+        m_things.erase(std::forward<Args>(args)...);
+    }
+
+    /**
+     * @brief Returns context's thing allocator.
+     *
+     * @return The thing allocator.
+     */
+    thing_allocator<std::byte> thing_alloc() const { return m_thingAllocator; }
+
+    thing_type_store& thing_type_store() { return m_thingTypeStore; }
+private:
+    handle_container<mod_h>      m_modules;
+    handle_container<thing_h>    m_things;
+    handle_container<executor_h> m_executors;
+
+    furlang::arena             m_thingArena;
+    thing_allocator<std::byte> m_thingAllocator;
+    class thing_type_store     m_thingTypeStore;
 };
 
 } // namespace furvm

furvm/include/furvm/detail/handle.hpp

@@ -0,0 +1,39 @@
+#ifndef FURVM_DETAIL_HANDLE_HPP
+#define FURVM_DETAIL_HANDLE_HPP
+
+#include <functional>
+#include <type_traits>
+
+namespace furvm {
+namespace detail {
+
+/**
+ * @brief Default specialization for header_has_refcount type trait.
+ */
+template <typename Header, typename = void>
+struct header_has_refcount : std::false_type {};
+
+/**
+ * @brief Specialization for header_has_refcount type trait.
+ */
+template <typename Header>
+struct header_has_refcount<Header,
+    std::void_t<decltype(std::declval<Header&>().acquire()),
+        decltype(std::declval<Header&>().release()),
+        decltype(std::declval<Header&>().reference_count())>> : std::true_type {};
+
+/**
+ * @brief An alias for header_has_refcount's value.
+ */
+template <typename Header>
+static constexpr auto header_has_refcount_v = header_has_refcount<Header>::value;
+
+template <typename Handle, typename IdHash = std::hash<typename Handle::id_type>>
+struct handle_hash {
+    std::size_t operator()(const Handle& handle) const { return IdHash{}(handle.id()); }
+};
+
+} // namespace detail
+} // namespace furvm
+
+#endif // FURVM_DETAIL_HANDLE_HPP

furvm/include/furvm/detail/serialization.hpp

@@ -0,0 +1,176 @@
+#ifndef FURVM_DETAIL_SERIALIZATION_HPP
+#define FURVM_DETAIL_SERIALIZATION_HPP
+
+#include <cstdint>
+#include <ostream>
+#include <string>
+
+namespace furvm {
+namespace detail {
+
+/**
+ * @brief Serializes an integer.
+ *
+ * @param os Output stream.
+ * @param value Integer.
+ * @return The output stream.
+ */
+std::ostream& serialize(std::ostream& os, std::int8_t value);
+
+/**
+ * @brief Serializes an integer.
+ *
+ * @param os Output stream.
+ * @param value Integer.
+ * @return The output stream.
+ */
+std::ostream& serialize(std::ostream& os, std::int16_t value);
+
+/**
+ * @brief Serializes an integer.
+ *
+ * @param os Output stream.
+ * @param value Integer.
+ * @return The output stream.
+ */
+std::ostream& serialize(std::ostream& os, std::int32_t value);
+
+/**
+ * @brief Serializes an integer.
+ *
+ * @param os Output stream.
+ * @param value Integer.
+ * @return The output stream.
+ */
+std::ostream& serialize(std::ostream& os, std::int64_t value);
+
+/**
+ * @brief Serializes an integer.
+ *
+ * @param os Output stream.
+ * @param value Integer.
+ * @return The output stream.
+ */
+std::ostream& serialize(std::ostream& os, std::uint8_t value);
+
+/**
+ * @brief Serializes an integer.
+ *
+ * @param os Output stream.
+ * @param value Integer.
+ * @return The output stream.
+ */
+std::ostream& serialize(std::ostream& os, std::uint16_t value);
+
+/**
+ * @brief Serializes an integer.
+ *
+ * @param os Output stream.
+ * @param value Integer.
+ * @return The output stream.
+ */
+std::ostream& serialize(std::ostream& os, std::uint32_t value);
+
+/**
+ * @brief Serializes an integer.
+ *
+ * @param os Output stream.
+ * @param value Integer.
+ * @return The output stream.
+ */
+std::ostream& serialize(std::ostream& os, std::uint64_t value);
+
+/**
+ * @brief Serializes a string.
+ *
+ * @param os Output stream.
+ * @param value String.
+ * @return The output stream.
+ */
+std::ostream& serialize(std::ostream& os, const std::string& value);
+
+/**
+ * @brief Deserializes an integer.
+ *
+ * @param is Input stream.
+ * @param value Integer.
+ * @return The input stream.
+ */
+std::istream& load(std::istream& is, std::int8_t& value);
+
+/**
+ * @brief Deserializes an integer.
+ *
+ * @param is Input stream.
+ * @param value Integer.
+ * @return The input stream.
+ */
+std::istream& load(std::istream& is, std::int16_t& value);
+
+/**
+ * @brief Deserializes an integer.
+ *
+ * @param is Input stream.
+ * @param value Integer.
+ * @return The input stream.
+ */
+std::istream& load(std::istream& is, std::int32_t& value);
+
+/**
+ * @brief Deserializes an integer.
+ *
+ * @param is Input stream.
+ * @param value Integer.
+ * @return The input stream.
+ */
+std::istream& load(std::istream& is, std::int64_t& value);
+
+/**
+ * @brief Deserializes an integer.
+ *
+ * @param is Input stream.
+ * @param value Integer.
+ * @return The input stream.
+ */
+std::istream& load(std::istream& is, std::uint8_t& value);
+
+/**
+ * @brief Deserializes an integer.
+ *
+ * @param is Input stream.
+ * @param value Integer.
+ * @return The input stream.
+ */
+std::istream& load(std::istream& is, std::uint16_t& value);
+
+/**
+ * @brief Deserializes an integer.
+ *
+ * @param is Input stream.
+ * @param value Integer.
+ * @return The input stream.
+ */
+std::istream& load(std::istream& is, std::uint32_t& value);
+
+/**
+ * @brief Deserializes an integer.
+ *
+ * @param is Input stream.
+ * @param value Integer.
+ * @return The input stream.
+ */
+std::istream& load(std::istream& is, std::uint64_t& value);
+
+/**
+ * @brief Deserializes a string.
+ *
+ * @param is Input stream.
+ * @param value String.
+ * @return The input stream.
+ */
+std::istream& load(std::istream& is, std::string& value);
+
+} // namespace detail
+} // namespace furvm
+
+#endif // FURVM_DETAIL_SERIALIZATION_HPP

furvm/include/furvm/exceptions.hpp

@@ -5,6 +5,75 @@
 
 namespace furvm {
 
+class bad_thing_access : public std::exception {
+public:
+    bad_thing_access()           = default;
+    ~bad_thing_access() override = default;
+
+    /**
+     * @brief Move constructor.
+     */
+    bad_thing_access(bad_thing_access&&) noexcept = default;
+
+    /**
+     * @brief Move constructor.
+     */
+    bad_thing_access& operator=(bad_thing_access&&) noexcept = default;
+
+    /**
+     * @brief Copy constructor.
+     */
+    bad_thing_access(const bad_thing_access&) = default;
+
+    /**
+     * @brief Copy constructor.
+     */
+    bad_thing_access& operator=(const bad_thing_access&) = default;
+public:
+    /**
+     * @brief Returns a C-style string describing the cause of the error.
+     *
+     * @return The cause of the error.
+     */
+    const char* what() const noexcept override { return "bad thing access"; }
+};
+
+/**
+ * @brief Bad constant access exception.
+ */
+class bad_constant_access : public std::exception {
+public:
+    bad_constant_access()           = default;
+    ~bad_constant_access() override = default;
+
+    /**
+     * @brief Move constructor.
+     */
+    bad_constant_access(bad_constant_access&&) noexcept = default;
+
+    /**
+     * @brief Move constructor.
+     */
+    bad_constant_access& operator=(bad_constant_access&&) noexcept = default;
+
+    /**
+     * @brief Copy constructor.
+     */
+    bad_constant_access(const bad_constant_access&) = default;
+
+    /**
+     * @brief Copy constructor.
+     */
+    bad_constant_access& operator=(const bad_constant_access&) = default;
+public:
+    /**
+     * @brief Returns a C-style string describing the cause of the error.
+     *
+     * @return The cause of the error.
+     */
+    const char* what() const noexcept override { return "bad constant access"; }
+};
+
 class stack_underflow : public std::exception {
 public:
     stack_underflow()           = default;

furvm/include/furvm/executor.hpp

@@ -2,8 +2,12 @@
 #define FURVM_EXECUTOR_HPP
 
 #include "furvm/fwd.hpp"
+#include "furvm/module.hpp" // IWYU pragma: keep
+#include "furvm/thing.hpp"  // IWYU pragma: keep
 
+#include <optional>
 #include <stack>
+#include <utility>
 #include <vector>
 
 namespace furvm {
@@ -26,15 +30,6 @@ static inline executor_flags operator~(executor_flags flags) {
 }
 
 class executor {
-private:
-    /**
-     * @brief A private token for the private constructor.
-     *
-     * Also `egzekutor` in Polish translates to `executor` I think.
-     */
-    struct egzekutor {
-        explicit egzekutor() = default;
-    };
 public:
     /**
      * @brief Executor frame.
@@ -42,22 +37,23 @@ public:
      * Call frame.
      */
     struct frame {
-        mod_p       mod;       /**< Shared pointer to a module with the bytecode. */
+        mod_h       mod;       /**< Handle to the frame's module. */
         std::size_t position;  /**< Cursor to a current instruction in the bytecode. */
         std::size_t stackBase; /**< Snapshot of the stack size before this frame. */
 
-        std::vector<thing_p> variables; /**< Frame variables. */
+        thing_type*          returnType; /**< Return type. */
+        std::vector<thing_h> variables;  /**< Frame variables. */
     };
 public:
     /**
-     * @brief Private constructor.
+     * @brief Returns a new executor.
      *
-     * @param id
-     * @param context
+     * @param context Context.
      */
-    executor(egzekutor, executor_handle id, const context_p& context);
+    executor(const context_p& context)
+      : m_context(context) {}
 
-    ~executor();
+    ~executor() = default;
 
     /**
      * @brief Move constructor.
@@ -69,24 +65,16 @@ public:
      */
     executor& operator=(executor&&) noexcept = default;
 
-    executor(const executor&)            = delete;
-    executor& operator=(const executor&) = delete;
-public:
     /**
-     * @brief Returns a new executor.
-     *
-     * @param context Furvm context.
-     * @return Shared pointer to the new executor.
+     * @brief Copy constructor.
      */
-    static executor_p create(const context_p& context);
-public:
-    /**
-     * @brief Returns an id of this executor.
-     *
-     * @return The id.
-     */
-    executor_handle id() const { return m_id; }
+    executor(const executor&) = default;
 
+    /**
+     * @brief Copy constructor.
+     */
+    executor& operator=(const executor&) = default;
+public:
     /**
      * @brief Returns flags of this executor.
      *
@@ -97,9 +85,10 @@ public:
     /**
      * @brief Pushes a new frame.
      *
-     * @param function Function.
+     * @param mod Handle to the frame's module.
+     * @param function Frame's function.
      */
-    void push_frame(const function_p& function);
+    void push_frame(const mod_h& mod, function function);
 
     /**
      * @brief Pops the top frame.
@@ -116,68 +105,77 @@ public:
     frame frame() const;
 public:
     /**
-     * @brief Pushes a thing onto the stack.
+     * @brief Pushes a thing handle onto the stack.
      *
-     * @param thing The thing to push.
+     * @param handle Thing handle.
      */
-    void push_thing(const thing_p& thing);
+    template <typename HandleFwd>
+    void push_thing(HandleFwd&& handle) {
+        m_stack.emplace(std::forward<HandleFwd>(handle));
+    }
 
     /**
      * @brief Pushes a thing onto the stack.
      *
-     * @param thing The thing to push.
+     * Registers a new thing and pushes its handle onto the stack.
+     *
+     * @param thing Thing.
+     * @return The pushed handle.
      */
-    void push_thing(thing_p&& thing);
+    thing_h push_thing(class thing<>&& thing);
 
     /**
      * @brief Pops a thing from the stack.
      *
-     * @return The popped thing.
+     * @return A handle to the popped thing.
      */
-    thing_p pop_thing();
+    thing_h pop_thing();
 
     /**
      * @brief Returns the top thing on the stack.
      *
-     * @return The thing.
+     * @return A handle to the top thing.
      */
-    thing_p thing() const;
+    thing_h thing() const;
 public:
     /**
-     * @brief Stores a thing in a variable.
+     * @brief Stores a thing in a frame variable.
      *
-     * @param variable Variable to store the thing in.
-     * @param thing Thing to store.
+     * @param variable Id of the variable in which the handle will be put.
+     * @param thing Thing handle.
      */
-    void store_thing(variable_t variable, const thing_p& thing);
+    void store_thing(variable_t variable, const thing_h& thing);
 
     /**
-     * @brief Stores a thing in a variable.
+     * @brief Stores a thing in a frame variable.
      *
-     * @param variable Variable to store the thing in.
-     * @param thing Thing to store.
+     * @param variable Id of the variable in which the handle will be put.
+     * @param thing Thing handle.
      */
-    void store_thing(variable_t variable, thing_p&& thing);
+    void store_thing(variable_t variable, thing_h&& thing);
 
     /**
      * @brief Returns a thing stored in a variable.
      *
-     * @param variable Variable where the thing is stored.
-     * @return The thing stored in the variable.
+     * @param variable Id of the variable from which the handle will be fetched.
+     * @return A handle stored in the variable.
      */
-    thing_p load_thing(variable_t variable) const;
+    thing_h load_thing(variable_t variable) const;
 public:
     /**
      * @brief Executes next instruction.
      */
     void step();
 private:
-    executor_handle m_id;
-    executor_flags  m_flags{}; // NOLINT(bugprone-invalid-enum-default-initialization)
-    context_p       m_context;
+    thing_type thing_type_impl(mod_h mod, mod_type type) const;
+
+    thing_type* thing_type(const mod_h& mod, const mod_type& type) const;
+private:
+    executor_flags m_flags{}; // NOLINT(bugprone-invalid-enum-default-initialization)
+    context_p      m_context;
 
     std::stack<struct frame> m_frames;
-    std::stack<thing_p>      m_stack;
+    std::stack<thing_h>      m_stack;
 };
 
 } // namespace furvm

furvm/include/furvm/function.hpp

@@ -1,11 +1,17 @@
 #ifndef FURVM_FUNCTION_HPP
 #define FURVM_FUNCTION_HPP
 
+#include "furlang/utility/hash.hpp"
 #include "furvm/fwd.hpp"
-#include "furvm/module.hpp" // IWYU pragma: keep
+#include "furvm/handle.hpp" // IWYU pragma: keep
 
-#include <functional>
+#include <cstdint>
+#include <optional>
 #include <stdexcept>
+#include <string>
+#include <type_traits>
+#include <utility>
+#include <vector>
 
 namespace furvm {
 
@@ -15,38 +21,80 @@ enum class function_t : std::uint8_t {
     Import,     /**< A function imported from another module. */
 };
 
-using native_function = std::function<void(executor&)>;
+/**
+ * @brief A native function.
+ */
+using native_function = std::string;
+
+/**
+ * @brief A function import.
+ */
+struct import_function {
+    mod_id      mod;
+    function_id function;
+};
+
+/**
+ * @brief Function signature.
+ */
+struct function_sig {
+    std::vector<mod_type_h>   params;
+    std::optional<mod_type_h> returnType;
+
+    bool operator==(const function_sig& rhs) const { return params == rhs.params; }
+
+    bool operator!=(const function_sig& rhs) const { return !this->operator==(rhs); }
+};
 
 class function {
-private:
-    /**
-     * @brief A private token for the private constructor.
-     *
-     * Also `funkcja` in Polish translates to `function` from what I heard.
-     */
-    struct funkcja {
-        explicit funkcja() = default;
-    };
 public:
     /**
-     * @brief Private constructor.
+     * @brief Constructs a normal function.
      *
-     * @param id
-     * @param position
-     * @param mod
+     * @param signature Function's signature.
+     * @param position Offset in bytecode of the function.
      */
-    function(funkcja, function_handle id, std::size_t position, const mod_p& mod);
+    template <typename SigFwd, typename = std::enable_if_t<std::is_constructible_v<function_sig, SigFwd>>>
+    function(SigFwd&& signature, bytecode_pos position)
+      : m_type(function_t::Normal), m_signature(std::forward<SigFwd>(signature)), m_value(position) {}
 
     /**
-     * @brief Private constructor.
+     * @brief Constructs a native function.
      *
-     * @param id
-     * @param native
-     * @param mod
+     * @param signature Function's signature.
+     * @param native Native function tag.
      */
-    function(funkcja, function_handle id, const native_function& native, const mod_p& mod);
+    template <typename SigFwd,
+        typename Native,
+        typename = std::enable_if_t<std::is_constructible_v<native_function, Native> &&
+                                    std::is_constructible_v<function_sig, SigFwd>>>
+    function(SigFwd&& signature, Native&& native)
+      : m_type(function_t::Native),
+        m_signature(std::forward<SigFwd>(signature)),
+        m_value(std::forward<Native>(native)) {}
 
-    ~function() = default;
+    /**
+     * @brief Constructs an import function.
+     *
+     * @param mod Module's id.
+     * @param function Function's id.
+     */
+    template <typename ModFwd, typename = std::enable_if_t<std::is_constructible_v<mod_id, ModFwd>>>
+    function(ModFwd&& mod, function_id function)
+      : m_type(function_t::Import), m_signature(), m_value(import_function{ std::forward<ModFwd>(mod), function }) {}
+
+    /**
+     * @brief Constructs an import function.
+     *
+     * @param mod Module.
+     * @param function Function.
+     */
+    function(const mod_h& mod, const function_h& function);
+
+    /**
+     * @brief Destructs a function.
+     */
+    ~function();
 
     /**
      * @brief Move constructor.
@@ -58,33 +106,16 @@ public:
      */
     function& operator=(function&&) noexcept;
 
-    function(const function&)            = delete;
-    function& operator=(const function&) = delete;
-public:
     /**
-     * @brief Returns a new function.
-     *
-     * @param mod Module.
-     * @param args Arguments to pass to the function constructor.
-     * @return The new function.
+     * @brief Copy constructor.
      */
-    template <typename... Args,
-        typename = std::enable_if_t<std::is_constructible_v<function, funkcja, function_handle, Args..., const mod_p&>>>
-    static function_p create(const mod_p& mod, Args&&... args) {
-        function_handle id = mod->m_functions.size();
+    function(const function&);
 
-        auto func = std::make_shared<function>(funkcja{}, id, std::forward<Args>(args)..., mod);
-        mod->m_functions.emplace(mod->m_functions.begin() + id, func);
-        return std::move(func);
-    }
-public:
     /**
-     * @brief Returns an id of this function.
-     *
-     * @return The id.
+     * @brief Copy constructor.
      */
-    constexpr function_handle id() const { return m_id; }
-
+    function& operator=(const function&);
+public:
     /**
      * @brief Returns a type of this function.
      *
@@ -93,14 +124,14 @@ public:
     constexpr function_t type() const { return m_type; }
 
     /**
-     * @brief Returns a parent module of this function.
+     * @brief Returns this function's signature.
      *
-     * @return A shared pointer to the module.
+     * @return The signature.
      */
-    const mod_p& mod() const { return m_module; }
+    function_sig signature() const { return m_signature; }
 public:
     /**
-     * @brief Returns a value for normal function.
+     * @brief Returns normal function's value.
      *
      * @return The value.
      */
@@ -110,7 +141,7 @@ public:
     }
 
     /**
-     * @brief Returns a value for native function.
+     * @brief Returns native function's value.
      *
      * @return The value.
      */
@@ -120,47 +151,34 @@ public:
     }
 
     /**
-     * @brief Returns a module of imported function.
+     * @brief Returns import function's value.
      *
-     * @return A handle to the module.
+     * @return The value.
      */
-    module_handle imported_module() const {
+    const import_function& imp() const {
         if (m_type != function_t::Import) throw std::runtime_error("function type mismatch");
-        return m_value.imp.mod;
-    }
-
-    /**
-     * @brief Returns a module of imported function.
-     *
-     * @return A handle to the module.
-     */
-    function_handle imported_function() const {
-        if (m_type != function_t::Import) throw std::runtime_error("function type mismatch");
-        return m_value.imp.function;
+        return m_value.imp;
     }
 private:
-    function_handle m_id;
-    function_t      m_type;
-    mod_p           m_module;
+    function_t   m_type;
+    function_sig m_signature;
 
     union value {
         std::size_t     position = 0;
         native_function native;
-        struct {
-            module_handle   mod;
-            function_handle function;
-        } imp;
+        import_function imp;
 
         value() = default;
 
         value(std::size_t position)
           : position(position) {}
 
-        value(const native_function& native)
-          : native(native) {}
+        template <typename Native, typename = std::enable_if_t<std::is_constructible_v<native_function, Native>>>
+        value(Native&& native)
+          : native(std::forward<Native>(native)) {}
 
-        value(module_handle mod, function_handle function)
-          : imp({ mod, function }) {}
+        value(const import_function& imp)
+          : imp(imp) {}
 
         ~value() {}
 
@@ -171,6 +189,14 @@ private:
     } m_value;
 };
 
+namespace detail {
+
+struct function_sig_hash {
+    std::size_t operator()(const function_sig& signature) const;
+};
+
+} // namespace detail
+
 } // namespace furvm
 
 #endif // FURVM_FUNCTION_HPP

furvm/include/furvm/furvm.hpp

@@ -0,0 +1,12 @@
+#ifndef FURVM_HPP
+#define FURVM_HPP
+
+#include "furvm/context.hpp"     // IWYU pragma: export
+#include "furvm/executor.hpp"    // IWYU pragma: export
+#include "furvm/function.hpp"    // IWYU pragma: export
+#include "furvm/fwd.hpp"         // IWYU pragma: export
+#include "furvm/handle.hpp"      // IWYU pragma: export
+#include "furvm/instruction.hpp" // IWYU pragma: export
+#include "furvm/thing.hpp"       // IWYU pragma: export
+
+#endif // FURVM_HPP

furvm/include/furvm/fwd.hpp

@@ -4,6 +4,7 @@
 #include <cstddef> // IWYU pragma: export
 #include <cstdint> // IWYU pragma: export
 #include <memory>
+#include <string>
 
 /**
  * @brief Furlang's virtual machine.
@@ -17,6 +18,40 @@ namespace furvm {
  */
 using byte = std::uint8_t;
 
+/**
+ * @brief An offset into bytecode.
+ */
+using bytecode_pos = std::uint64_t;
+
+/**
+ * @brief Handle header with reference count.
+ */
+template <typename Id>
+class refcount_header;
+
+/**
+ * @brief Generic handle header.
+ */
+template <typename Id>
+class generic_header;
+
+/**
+ * @brief Generic furvm object handle.
+ *
+ * @tparam Value Type of the handle's value.
+ * @tparam Header Type of the handle's header.
+ */
+template <typename Value, typename Header>
+class handle;
+
+/**
+ * @brief Container for the handles.
+ *
+ * @tparam Handle Type of the container's handle.
+ */
+template <typename Handle, typename = void>
+class handle_container;
+
 // constant.hpp
 
 /**
@@ -68,18 +103,24 @@ enum class function_t : std::uint8_t;
  */
 class function;
 
-/**
- * @brief An alias to a function shared pointer.
- */
-using function_p = std::shared_ptr<function>;
-
 /**
  * @brief Furvm function's index.
  */
-using function_handle = std::uint16_t;
+using function_id = std::uint16_t;
+
+/**
+ * @brief A handle to a furvm function.
+ */
+using function_h = handle<function, refcount_header<function_id>>;
 
 // module.hpp
 
+struct mod_type;
+
+using mod_type_id = std::uint32_t;
+
+using mod_type_h = handle<mod_type, generic_header<mod_type_id>>;
+
 /**
  * @class mod
  * @brief Module.
@@ -94,17 +135,21 @@ class mod;
 using mod_p = std::shared_ptr<mod>;
 
 /**
- * @brief Furvm module's index.
+ * @brief An alias for a module's identifier.
  */
-using module_handle = std::uint32_t;
-
-// thing.hpp
+using mod_id = std::string;
 
 /**
- * @enum thing_t
- * @brief Thing type.
+ * @brief A handle to a furvm module.
  */
-enum class thing_t : std::uint8_t;
+using mod_h = handle<mod, refcount_header<mod_id>>;
+
+// thing_allocator.hpp
+
+template <typename T>
+class thing_allocator;
+
+// thing.hpp
 
 /**
  * @class bad_thing_access
@@ -112,23 +157,26 @@ enum class thing_t : std::uint8_t;
  */
 class bad_thing_access;
 
+using thing_type_id = std::uint32_t;
+
 /**
  * @class thing
  * @brief Furvm thing.
  *
  * A stack element. Think of it like of a value in C++ or I guess a class in java.
  */
+template <template <typename> typename Allocator = thing_allocator>
 class thing;
 
-/**
- * @brief An alias to a thing shared pointer.
- */
-using thing_p = std::shared_ptr<thing>;
-
 /**
  * @brief Furvm thing's index.
  */
-using thing_handle = std::uint32_t;
+using thing_id = std::uint32_t;
+
+/**
+ * @brief A handle to a thing.
+ */
+using thing_h = handle<thing<thing_allocator>, refcount_header<thing_id>>;
 
 // executor.hpp
 
@@ -159,7 +207,12 @@ using executor_p = std::shared_ptr<executor>;
 /**
  * @brief Furvm executor's index.
  */
-using executor_handle = std::uint32_t;
+using executor_id = std::uint32_t;
+
+/**
+ * @brief A handle to an executor.
+ */
+using executor_h = handle<executor, refcount_header<executor_id>>;
 
 // context.hpp
 

furvm/include/furvm/handle.hpp

@@ -0,0 +1,448 @@
+#ifndef FURVM_HANDLE_HPP
+#define FURVM_HANDLE_HPP
+
+#include "furvm/detail/handle.hpp"
+#include "furvm/fwd.hpp"
+
+#include <atomic>
+#include <functional>
+#include <tuple>
+#include <type_traits>
+#include <unordered_map>
+#include <utility>
+#include <vector>
+
+namespace furvm {
+
+// TODO: Implement generational indexes
+
+template <typename Id>
+class refcount_header {
+public:
+    using id_type       = Id;            /**< Id type. */
+    using refcount_type = std::uint32_t; /**< Reference count type. */
+public:
+    /**
+     * @brief Constructs a reference counting header.
+     *
+     * @param id Identifier of the handle's value.
+     * @param refCount Handle's reference count.
+     * @param onRelease Callback function.
+     */
+    template <typename IdFwd, typename Func>
+    refcount_header(IdFwd&& id, refcount_type refCount, Func&& onRelease)
+      : m_id(std::forward<IdFwd>(id)), m_refCount(refCount), m_onRelease(std::forward<Func>(onRelease)) {}
+public:
+    /**
+     * @brief Returns the header's reference count.
+     *
+     * @return The reference count.
+     */
+    refcount_type reference_count() const { return m_refCount; }
+
+    /**
+     * @brief Increments the header's reference count.
+     */
+    void acquire() { ++m_refCount; }
+
+    /**
+     * @brief Decrements the header's reference count.
+     *
+     * If the reference count reaches 0, the onRelease callback passed in the constructor will be called.
+     */
+    void release() {
+        --m_refCount;
+        if (m_refCount == 0) m_onRelease(m_id);
+    }
+public:
+    /**
+     * @brief Returns the header's identifier.
+     *
+     * @return The identifier.
+     */
+    id_type id() const { return m_id; }
+private:
+    id_type                             m_id;
+    std::atomic<refcount_type>          m_refCount;
+    std::function<void(const id_type&)> m_onRelease;
+};
+
+template <typename Id>
+class generic_header {
+public:
+    using id_type = Id; /**< Id type. */
+public:
+    /**
+     * @brief Constructs a generic header.
+     *
+     * @param id Identifier of the handle.
+     */
+    generic_header(id_type id)
+      : m_id(id) {}
+public:
+    /**
+     * @brief Returns the header's identifier.
+     */
+    id_type id() const { return m_id; }
+private:
+    id_type m_id;
+};
+
+template <typename Value, typename Header = refcount_header<std::uint32_t>>
+class handle {
+public:
+    using value_type      = Value;        /** Value type. */
+    using reference       = Value&;       /** Reference type. */
+    using const_reference = const Value&; /** Constant reference type. */
+    using pointer         = Value*;       /** Pointer type. */
+    using const_pointer   = const Value*; /** Constant pointer type. */
+public:
+    using id_type = typename Header::id_type; /** Id type of the header. */
+
+    using header_type = Header;
+public:
+    using pair_type = std::pair<Header, Value>; /** Type of a header-value pair. */
+public:
+    handle() = default;
+
+    /**
+     * @brief Constructs a handle.
+     *
+     * @param value A pointer to the header-value pair.
+     */
+    handle(pair_type* value)
+      : m_value(value) {
+        if constexpr (detail::header_has_refcount_v<Header>) {
+            m_value->first.acquire();
+        }
+    }
+
+    /**
+     * @brief Destructs a handle.
+     */
+    ~handle() {
+        if constexpr (detail::header_has_refcount_v<Header>) {
+            if (m_value != nullptr) m_value->first.release();
+        }
+        m_value = nullptr;
+    }
+
+    /**
+     * @brief Move constructor.
+     */
+    handle(handle&& other) noexcept
+      : m_value(other.m_value) {
+        other.m_value = nullptr;
+    }
+
+    /**
+     * @brief Move constructor.
+     */
+    handle& operator=(handle&& other) noexcept {
+        if (this == &other) return *this;
+        m_value       = other.m_value;
+        other.m_value = nullptr;
+        return *this;
+    }
+
+    /**
+     * @brief Copy constructor.
+     */
+    handle(const handle& other)
+      : m_value(other.m_value) {
+        if constexpr (detail::header_has_refcount_v<Header>) {
+            m_value->first.acquire();
+        }
+    }
+
+    /**
+     * @brief Copy constructor.
+     */
+    handle& operator=(const handle& other) {
+        if (this == &other) return *this;
+        m_value = other.m_value;
+        if constexpr (detail::header_has_refcount_v<Header>) {
+            m_value->first.acquire();
+        }
+        return *this;
+    }
+public:
+    /**
+     * @brief Returns an identifier of the handle's header.
+     *
+     * @return The header's identifier.
+     */
+    id_type id() const { return m_value->first.id(); }
+
+    /**
+     * @brief Returns whether the handle is empty.
+     *
+     * @return true if the handle is empty.
+     */
+    bool empty() const { return m_value == nullptr; }
+
+    /**
+     * @brief Returns the handle's header reference count.
+     *
+     * @return The reference count.
+     */
+    template <typename U = Header, typename = std::enable_if_t<detail::header_has_refcount_v<U>>>
+    auto reference_count() const {
+        return m_value->first.reference_count();
+    }
+
+    /**
+     * @brief Returns a pointer to the handle's value.
+     *
+     * @return The value pointer.
+     */
+    pointer operator->() { return &m_value->second; }
+
+    /**
+     * @brief Returns a pointer to the handle's value.
+     *
+     * @return The value pointer.
+     */
+    const_pointer operator->() const { return &m_value->second; }
+
+    /**
+     * @brief Returns a reference to the handle's value.
+     *
+     * @return The value reference.
+     */
+    reference operator*() { return m_value->second; }
+
+    /**
+     * @brief Returns a reference to the handle's value.
+     *
+     * @return The value reference.
+     */
+    const_reference operator*() const { return m_value->second; }
+
+    /**
+     * @brief Returns a reference to the handle's value.
+     *
+     * @return The value reference.
+     */
+    reference value() { return m_value->second; }
+
+    /**
+     * @brief Returns a reference to the handle's value.
+     *
+     * @return The value reference.
+     */
+    const_reference value() const { return m_value->second; }
+public:
+    /**
+     * @brief Invalidates the handle without releasing.
+     */
+    void dispatch() { m_value = nullptr; }
+public:
+    bool operator==(const handle& rhs) const { return m_value == rhs.m_value; }
+
+    bool operator!=(const handle& rhs) const { return !this->operator==(rhs); }
+private:
+    pair_type* m_value = nullptr;
+};
+
+template <typename Handle>
+class handle_container<Handle, std::enable_if_t<!std::is_integral_v<typename Handle::id_type>>> {
+private:
+    using pair_type = typename Handle::pair_type; /**< Handle's pair type. */
+public:
+    using value_type  = std::remove_cv_t<std::remove_reference_t<Handle>>; /**< Handle type. */
+    using const_value = std::add_const_t<value_type>;                      /**< Constant handle type. */
+
+    using id_type = typename Handle::id_type; /**< Handle's header identifier type. */
+public:
+    handle_container()  = default;
+    ~handle_container() = default;
+
+    handle_container(handle_container&&) noexcept            = default;
+    handle_container& operator=(handle_container&&) noexcept = default;
+
+    handle_container(const handle_container&)            = delete;
+    handle_container& operator=(const handle_container&) = delete;
+public:
+    /**
+     * @brief Emplaces a new value.
+     *
+     * @param id Identifier of the emplaced value.
+     * @param args Arguments passed to the Handle's value type constructor.
+     * @return A handle to the emplaced value.
+     */
+    template <typename IdFwd,
+        typename... Args,
+        typename = std::enable_if_t<std::is_constructible_v<typename pair_type::second_type, Args...>>>
+    value_type emplace(IdFwd&& id, Args&&... args) {
+        id_type idFwd = std::forward<IdFwd>(id);
+        if (auto it = m_pairs.find(idFwd); it != m_pairs.end()) delete it->second;
+        auto pair = new pair_type(std::piecewise_construct,
+            std::forward_as_tuple(idFwd, 0, [&](const id_type& id) { erase(id); }),
+            std::forward_as_tuple(std::forward<Args>(args)...));
+        m_pairs.emplace(std::move(idFwd), pair);
+        return { pair };
+    }
+
+    /**
+     * @brief Returns a handle to the container's value.
+     *
+     * @param id Idenfifier of the value.
+     * @return The value.
+     */
+    template <typename IdFwd>
+    value_type at(IdFwd&& id) {
+        return { m_pairs.at(std::forward<IdFwd>(id)) };
+    }
+
+    /**
+     * @brief Returns a handle to the container's value.
+     *
+     * @param id Idenfifier of the value.
+     * @return The value.
+     */
+    template <typename IdFwd>
+    const_value at(IdFwd&& id) const {
+        return { m_pairs.at(std::forward<IdFwd>(id)) };
+    }
+
+    /**
+     * @brief Erases a value from the container.
+     *
+     * @param id Identifier of the value.
+     */
+    template <typename IdFwd>
+    void erase(IdFwd&& id) {
+        auto it = m_pairs.find(std::forward<IdFwd>(id));
+        if (it == m_pairs.end()) return;
+        delete it->second;
+        m_pairs.erase(it);
+    }
+
+    /**
+     * @brief Checks whether a handle exists inside.
+     *
+     * @param id Identifier of the handle.
+     * @return true if the handle exists insdie of this container.
+     */
+    template <typename IdFwd>
+    constexpr bool contains(IdFwd&& id) const {
+        return m_pairs.find(std::forward<IdFwd>(id)) != m_pairs.end();
+    }
+private:
+    std::unordered_map<id_type, pair_type*> m_pairs;
+};
+
+template <typename Handle>
+class handle_container<Handle, std::enable_if_t<std::is_integral_v<typename Handle::id_type>>> {
+private:
+    using pair_type = typename Handle::pair_type; /**< Handle's pair type. */
+public:
+    using value_type  = std::remove_cv_t<std::remove_reference_t<Handle>>; /**< Handle type. */
+    using const_value = std::add_const_t<value_type>;                      /**< Constant handle type. */
+
+    using id_type = typename Handle::id_type; /**< Handle's header identifier type. */
+public:
+    handle_container()  = default;
+    ~handle_container() = default;
+
+    handle_container(handle_container&&) noexcept            = default;
+    handle_container& operator=(handle_container&&) noexcept = default;
+
+    handle_container(const handle_container&)            = delete;
+    handle_container& operator=(const handle_container&) = delete;
+public:
+    /**
+     * @brief Emplaces a new value.
+     *
+     * @param id Identifier of the emplaced value.
+     * @param args Arguments passed to the Handle's value type constructor.
+     * @return A handle to the emplaced value.
+     */
+    template <typename... Args,
+        typename = std::enable_if_t<std::is_constructible_v<typename pair_type::second_type, Args...>>>
+    value_type emplace(id_type id, Args&&... args) {
+        if (id >= m_pairs.size()) {
+            m_pairs.resize(id + 1, nullptr);
+        } else if (m_pairs[id] != nullptr) {
+            delete m_pairs[id];
+        }
+
+        pair_type* newPair = nullptr;
+        if constexpr (detail::header_has_refcount_v<typename Handle::header_type>) {
+            newPair = new pair_type(std::piecewise_construct,
+                std::forward_as_tuple(id, 0, [&](const id_type& id) { erase(id); }),
+                std::forward_as_tuple(std::forward<Args>(args)...));
+        } else {
+            newPair = new pair_type(std::piecewise_construct,
+                std::forward_as_tuple(id),
+                std::forward_as_tuple(std::forward<Args>(args)...));
+        }
+
+        m_pairs[id] = newPair;
+        return { newPair };
+    }
+
+    /**
+     * @brief Emplaces a new value.
+     *
+     * Emplaces a new value with an automatically-assigned identifier.
+     *
+     * @param args Arguments passed to the Handle's value type constructor.
+     * @return A handle to the emplaced value.
+     */
+    template <typename... Args,
+        typename = std::enable_if_t<std::is_constructible_v<typename Handle::pair_type::second_type, Args...>>>
+    value_type emplace_back(Args&&... args) {
+        return emplace(static_cast<id_type>(m_pairs.size()), std::forward<Args>(args)...);
+    }
+
+    /**
+     * @brief Returns a handle to a value.
+     *
+     * @param id Identifier of the value.
+     * @return The value.
+     */
+    value_type at(id_type id) { return { m_pairs.at(id) }; }
+
+    /**
+     * @brief Returns a handle to a value.
+     *
+     * @param id Identifier of the value.
+     * @return The value.
+     */
+    const_value at(id_type id) const { return { m_pairs.at(id) }; }
+
+    /**
+     * @brief Erases a value from the container.
+     *
+     * @param id Identifier of the value.
+     */
+    void erase(id_type id) {
+        if (id >= m_pairs.size()) return;
+        delete m_pairs[id];
+        m_pairs[id] = nullptr;
+    }
+
+    /**
+     * @brief Checks whether a handle exists inside.
+     *
+     * @param id Identifier of the handle.
+     * @return true if the handle exists insdie of this container.
+     */
+    constexpr bool contains(id_type id) const { return id < m_pairs.size() && m_pairs[id] != nullptr; }
+public:
+    auto begin() { return m_pairs.begin(); }
+    auto begin() const { return m_pairs.begin(); }
+    auto cbegin() const { return m_pairs.cbegin(); }
+
+    auto end() { return m_pairs.end(); }
+    auto end() const { return m_pairs.end(); }
+    auto cend() const { return m_pairs.cend(); }
+private:
+    std::vector<pair_type*> m_pairs;
+};
+
+} // namespace furvm
+
+#endif // FURVM_HANDLE_HPP

furvm/include/furvm/instruction.hpp

@@ -12,11 +12,34 @@ enum class instruction_t : byte {
     NoOperation = 0,
 
     /**
-     * @brief Pushes an integer from a byte onto the stack.
-     *
-     * Pushes an integer constructed from a next byte onto the stack.
+     * @brief Pushes an s8 integer from a byte onto the stack.
      */
-    PushB2I,
+    PushS8,
+
+    /**
+     * @brief Pushes an u8 integer from a byte onto the stack.
+     */
+    PushU8,
+
+    /**
+     * @brief Pushes an s16 integer from two byte onto the stack.
+     */
+    PushS16,
+
+    /**
+     * @brief Pushes an u16 integer from two byte onto the stack.
+     */
+    PushU16,
+
+    /**
+     * @brief Pushes an s32 integer from a byte onto the stack.
+     */
+    PushS32,
+
+    /**
+     * @brief Pushes an u32 integer from a byte onto the stack.
+     */
+    PushU32,
 
     /**
      * @brief Pushes a constant onto the stack.
@@ -25,6 +48,24 @@ enum class instruction_t : byte {
      */
     PushConstant,
 
+    /**
+     * @brief Pushes a new array onto the stack.
+     *
+     * Type is the next 4 bytes in little-endian.
+     * If the type is dynamic the array's size will be popped off of the stack.
+     */
+    Array,
+
+    /**
+     * @brief Pushes an element from an array onto the stack.
+     */
+    Get,
+
+    /**
+     * @brief Sets an array element.
+     */
+    Set,
+
     /**
      * @brief Pops top element from the stack.
      */
@@ -35,11 +76,23 @@ enum class instruction_t : byte {
      */
     Duplicate,
 
+    /**
+     * @brief Swaps two top elements of the stack.
+     */
+    Swap,
+
     /**
      * @brief Clones top element on the stack.
      */
     Clone,
 
+    /**
+     * @brief Pushes a new reference onto the stack.
+     *
+     * Pops the top thing from the stack and pushes its reference.
+     */
+    Reference,
+
     /**
      * @brief Adds two things together on the stack.
      */
@@ -65,6 +118,51 @@ enum class instruction_t : byte {
      */
     Mod,
 
+    /**
+     * @brief Compares two top-most things from the stack for equality.
+     */
+    Equals,
+
+    /**
+     * @brief Compares two top-most things from the stack for inequality.
+     */
+    NotEquals,
+
+    /**
+     * @brief Compares if the first top-most thing is less than the second top-most thing.
+     */
+    LessThan,
+
+    /**
+     * @brief Compares if the first top-most thing is greater than the second top-most thing.
+     */
+    GreaterThan,
+
+    /**
+     * @brief Compares if the first top-most thing is less than or equal to the second top-most thing.
+     */
+    LessEqual,
+
+    /**
+     * @brief Compares if the first top-most thing is greater than or equal to the second top-most thing.
+     */
+    GreaterEqual,
+
+    /**
+     * @brief Pushes a pointer of popped-off thing onto the stack.
+     */
+    Pointerof,
+
+    /**
+     * @brief Pushes a size of popped-off thing onto the stack.
+     */
+    Sizeof,
+
+    /**
+     * @brief Pushes a length of popped-off thing onto the stack.
+     */
+    Lengthof,
+
     /**
      * @brief Pushes a variable onto the stack.
      *
@@ -86,15 +184,25 @@ enum class instruction_t : byte {
      */
     Call,
 
+    /**
+     * @brief Jumps to an instruction relative to the current instruction.
+     *
+     * Jumps to an instruction relative to the current instruction with offset denoted by next byte.
+     */
+    Jump,
+
+    /**
+     * @brief Jumps to an instruction relative to the current instruction if top thing on the stack is not zero.
+     *
+     * Jumps to an instruction relative to the current instruction with offset denoted by next byte if the top thing on
+     * the stack is not zero (is true).
+     */
+    JumpNotZero,
+
     /**
      * @brief Pops the current call frame.
      */
     Return,
-
-    /**
-     * @brief Pops the current call frame and pushes the first element from the previous stack onto the new stack.
-     */
-    ReturnValue,
 };
 
 struct instruction {

furvm/include/furvm/module.hpp

@@ -1,27 +1,164 @@
 #ifndef FURVM_MODULE_HPP
 #define FURVM_MODULE_HPP
 
+#include "furlang/utility/hash.hpp"
+#include "furvm/function.hpp"
 #include "furvm/fwd.hpp"
+#include "furvm/handle.hpp"
 
+#include <functional>
+#include <istream>
+#include <ostream>
+#include <string>
+#include <type_traits>
+#include <unordered_map>
+#include <utility>
 #include <vector>
 
 namespace furvm {
 
+struct mod_type {
+    struct array {
+        mod_type_id typeId;
+        std::size_t size;
+    };
+
+    struct imprt {
+        mod_id      modId;
+        mod_type_id typeId;
+    };
+
+    enum type {
+        S8 = 0,
+        S16,
+        S32,
+        S64,
+        U8,
+        U16,
+        U32,
+        U64,
+        Ptr,
+        Ref,
+        Array,
+
+        Import,
+        Count,
+    } type;
+    union value {
+        std::nullptr_t null = nullptr;
+        mod_type_id    typeRef;
+        array          array;
+        imprt          imprt;
+
+        value() = default;
+
+        value(mod_type_id id)
+          : typeRef(id) {}
+
+        value(mod_type_id id, std::size_t size)
+          : array({}) {
+            array.typeId = id;
+            array.size   = size;
+        }
+
+        template <typename ModIdFwd, typename = std::enable_if_t<std::is_constructible_v<mod_id, ModIdFwd>>>
+        value(ModIdFwd&& modId, mod_type_id typeId)
+          : imprt({}) {
+            imprt.modId  = std::forward<ModIdFwd>(modId);
+            imprt.typeId = typeId;
+        }
+
+        ~value() {}
+
+        value(value&& other)                 = delete;
+        value& operator=(value&& other)      = delete;
+        value(const value& other)            = delete;
+        value& operator=(const value& other) = delete;
+    } value;
+
+    mod_type(enum type type)
+      : type(type) {}
+
+    mod_type(enum type type, mod_type_id typeRef)
+      : type(type), value(typeRef) {}
+
+    mod_type(mod_type_id id, std::size_t size)
+      : type(Array), value(id, size) {}
+
+    template <typename ModIdFwd, typename = std::enable_if_t<std::is_constructible_v<mod_id, ModIdFwd>>>
+    mod_type(ModIdFwd&& modId, mod_type_id typeId)
+      : type(Import), value(std::forward<ModIdFwd>(modId), typeId) {}
+
+    ~mod_type() {
+        switch (type) {
+        case Array: value.array.~array(); break;
+        case Import: value.imprt.~imprt(); break;
+        default: break;
+        }
+    }
+
+    mod_type(mod_type&& other) noexcept
+      : type(other.type) {
+        switch (type) {
+        case Array: new (&value.array) array(other.value.array); break;
+        case Import: new (&value.imprt) imprt(std::move(other.value.imprt)); break;
+        default: break;
+        }
+        other.type = Count;
+    }
+
+    mod_type& operator=(mod_type&& other) noexcept {
+        if (this == &other) return *this;
+        type = other.type;
+        switch (type) {
+        case Array: new (&value.array) array(other.value.array); break;
+        case Import: new (&value.imprt) imprt(std::move(other.value.imprt)); break;
+        default: break;
+        }
+        other.type = Count;
+        return *this;
+    }
+
+    mod_type(const mod_type& other)
+      : type(other.type) {
+        switch (type) {
+        case Array: new (&value.array) array(other.value.array); break;
+        case Import: new (&value.imprt) imprt(other.value.imprt); break;
+        default: break;
+        }
+    }
+
+    mod_type& operator=(const mod_type& other) {
+        if (this == &other) return *this;
+        type = other.type;
+        switch (type) {
+        case Array: new (&value.array) array(other.value.array); break;
+        case Import: new (&value.imprt) imprt(other.value.imprt); break;
+        default: break;
+        }
+        return *this;
+    }
+};
+
 class mod {
     friend class function;
     friend class serializer;
 public:
     using bytecode_t = std::vector<byte>; /**< An alias to a vector of bytes. */
+
+    static constexpr char MAGIC[4] = { 'F', 'u', 'r', 'M' }; /** Furvm module file magic. */
+
+    using native_function = std::function<void(executor&)>;
 public:
     /**
-     * @brief Construct a new module.
+     * @brief Constructs a module.
      *
-     * @param id Id of this module.
-     * @param args Arguments to forward to bytecode's constructor.
+     * @param name Name of the module.
+     * @param args Arguments forwarded to bytecode's constructor.
      */
     template <typename... Args, typename = std::enable_if_t<std::is_constructible_v<bytecode_t, Args...>>>
-    mod(module_handle id, Args&&... args)
-      : m_id(id), m_bytecode(std::forward<Args>(args)...) {}
+    mod(Args&&... args)
+      : m_bytecode(std::forward<Args>(args)...) {}
 
     ~mod() = default;
 
@@ -38,13 +175,6 @@ public:
     mod(const mod&)            = delete;
     mod& operator=(const mod&) = delete;
 public:
-    /**
-     * @brief Returns an id of this module.
-     *
-     * @return The id.
-     */
-    constexpr module_handle id() const { return m_id; }
-
     /**
      * @brief Returns a byte from bytecode of this module.
      *
@@ -52,18 +182,194 @@ public:
      * @return The byte.
      */
     constexpr byte byte(std::size_t offset) const { return m_bytecode.at(offset); }
+
+    /**
+     * @brief Returns the module's bytecode.
+     *
+     * @return A reference to the bytecode.
+     */
+    constexpr bytecode_t& bytecode() { return m_bytecode; }
+
+    /**
+     * @brief Returns the module's bytecode.
+     *
+     * @return A constant reference to the bytecode.
+     */
+    constexpr const bytecode_t& bytecode() const { return m_bytecode; }
 public:
     /**
-     * @brief Returns a function from this module.
+     * @brief Emplaces a function in the module's function container.
      *
-     * @param id Id of the function.
-     * @return The function.
+     * Emplaces the function in module's function container and name to function map and public functions map.
+     *
+     * @param args Arguments forwarded into the container's emplace_back function.
+     * @return A handle to the emplaced function.
      */
-    constexpr const function_p& function_at(function_handle id) const { return m_functions.at(id); }
+    template <typename... Args>
+    function_h emplace_function(Args&&... args) {
+        function_h function;
+        if constexpr (std::is_constructible_v<class function, Args...>) {
+            function = std::move(m_functions.emplace_back(std::forward<Args>(args)...));
+        } else {
+            function = std::move(m_functions.emplace(std::forward<Args>(args)...));
+        }
+        return std::move(function);
+    }
+
+    /**
+     * @brief Emplaces a function in the module's function container.
+     *
+     * Emplaces the function in module's function container and name to function map.
+     *
+     * @param name Name of the function.
+     * @param args Arguments forwarded into the container's emplace_back function.
+     * @return A handle to the emplaced function.
+     */
+    template <typename NameFwd,
+        typename... Args,
+        typename = std::enable_if_t<std::is_constructible_v<std::string, NameFwd>>>
+    function_h emplace_function(NameFwd&& name, Args&&... args) {
+        function_h function;
+        if constexpr (std::is_constructible_v<class function, Args...>) {
+            function = std::move(m_functions.emplace_back(std::forward<Args>(args)...));
+        } else {
+            function = std::move(m_functions.emplace(std::forward<Args>(args)...));
+        }
+        auto pair                       = std::make_pair(std::forward<NameFwd>(name), function->signature());
+        m_functionMap[function.id()]    = pair;
+        m_functionSigs[std::move(pair)] = function.id();
+        return std::move(function);
+    }
+
+    /**
+     * @brief Returns a function from the module.
+     *
+     * @param id Identifier of the function.
+     * @return A handle to the function.
+     */
+    auto function_at(function_id id) { return m_functions.at(id); }
+
+    /**
+     * @brief Returns a function from the module.
+     *
+     * @param id Identifier of the function.
+     * @return A handle to the function.
+     */
+    auto function_at(function_id id) const { return m_functions.at(id); }
+
+    /**
+     * @brief Returns a function from the module.
+     *
+     * @param name Name of the function.
+     * @return A handle to the function.
+     */
+    template <typename NameFwd,
+        typename SigFwd,
+        typename = std::enable_if_t<std::is_constructible_v<std::string, NameFwd> &&
+                                    std::is_constructible_v<function_sig, SigFwd>>>
+    auto function_at(NameFwd&& name, SigFwd&& signature) {
+        return function_at(
+            m_functionSigs.at(std::make_pair<>(std::forward<NameFwd>(name), std::forward<SigFwd>(signature))));
+    }
+
+    /**
+     * @brief Erases a function from the module's function container.
+     *
+     * @param id Identifier of the function.
+     */
+    void erase_function(function_id id) {
+        m_functions.erase(id);
+        if (auto it = m_functionMap.find(id); it != m_functionMap.end()) {
+            m_functionSigs.erase(it->second);
+            m_functionMap.erase(it);
+        }
+    }
+public:
+    template <typename NameFwd, typename Func>
+    void set_native_function(NameFwd&& name, Func&& func) {
+        m_nativeFunctions.emplace(std::forward<NameFwd>(name), std::forward<Func>(func));
+    }
+
+    template <typename NameFwd>
+    native_function get_native_function(NameFwd&& name) const {
+        return m_nativeFunctions.at(std::forward<NameFwd>(name));
+    }
+public:
+    /**
+     * @brief Emplaces a type in the context.
+     *
+     * @param args Arguments forwarded to the type constructor.
+     * @return The emplaced type.
+     */
+    template <typename... Args>
+    auto emplace_type(Args&&... args) {
+        if constexpr (std::is_constructible_v<mod_type, Args...>) {
+            return m_types.emplace_back(std::forward<Args>(args)...);
+        } else {
+            return m_types.emplace(std::forward<Args>(args)...);
+        }
+    }
+
+    /**
+     * @brief Returns a type from the context.
+     *
+     * @param args type's id.
+     * @return A handle to the type.
+     */
+    template <typename... Args>
+    auto type_at(Args&&... args) {
+        return m_types.at(std::forward<Args>(args)...);
+    }
+
+    /**
+     * @brief Returns a type from the context.
+     *
+     * @param args type's id.
+     * @return A handle to the type.
+     */
+    template <typename... Args>
+    auto type_at(Args&&... args) const {
+        return m_types.at(std::forward<Args>(args)...);
+    }
+
+    /**
+     * @brief Erases a type from the context.
+     *
+     * @param args type's id.
+     */
+    template <typename... Args>
+    void erase_type(Args&&... args) {
+        m_types.erase(std::forward<Args>(args)...);
+    }
+public:
+    /**
+     * @brief Prints the module in a bytecode form to an output stream.
+     *
+     * @param os Output stream.
+     * @return The output stream.
+     */
+    std::ostream& serialize(std::ostream& os) const;
+
+    /**
+     * @brief Loads a module in a bytecode form from an input stream.
+     *
+     * @param is Input stream.
+     * @return The loaded module.
+     */
+    static mod load(std::istream& is);
 private:
-    module_handle           m_id;
-    bytecode_t              m_bytecode;
-    std::vector<function_p> m_functions;
+    bytecode_t m_bytecode;
+
+    using pair_type = std::pair<std::string, function_sig>;
+    using pair_hash =
+        furlang::utility::pair_hash<std::string, function_sig, std::hash<std::string>, detail::function_sig_hash>;
+    std::unordered_map<pair_type, function_id, pair_hash> m_functionSigs;
+    std::unordered_map<function_id, pair_type>            m_functionMap;
+    handle_container<function_h>                          m_functions;
+
+    handle_container<mod_type_h> m_types;
+
+    std::unordered_map<std::string, native_function> m_nativeFunctions;
 };
 
 } // namespace furvm

furvm/include/furvm/serializer.hpp

@@ -1,20 +0,0 @@
-#ifndef FURVM_SERIALIZER_HPP
-#define FURVM_SERIALIZER_HPP
-
-#include "furvm/fwd.hpp"
-
-#include <ostream>
-
-namespace furvm {
-
-class serializer {
-public:
-    static constexpr byte          MODULE_MAGIC[4] = { 'F', 'u', 'r', 'M' };
-    static constexpr std::uint32_t VERSION         = 0;
-public:
-    static bool serialize_module(std::ostream& os, const mod_p& mod);
-};
-
-} // namespace furvm
-
-#endif // FURVM_SERIALIZER_HPP

furvm/include/furvm/thing.hpp

@@ -1,209 +1,743 @@
 #ifndef FURVM_THING_HPP
 #define FURVM_THING_HPP
 
-#include "furvm/context.hpp" // IWYU pragma: keep
+#include "furlang/arena.hpp"
+#include "furlang/utility/hash.hpp"
+#include "furvm/exceptions.hpp"
 #include "furvm/fwd.hpp"
+#include "furvm/thing_allocator.hpp" // IWYU pragma: keep
+
+#include <algorithm>
+#include <cstddef>
+#include <cstring>
+#include <functional>
+#include <limits>
+#include <new>
+#include <stdexcept>
+#include <type_traits>
+#include <unordered_map>
+#include <utility>
 
 namespace furvm {
 
-enum class thing_t : std::uint8_t {
-    Int32,
+struct thing_type {
+    using s8  = std::int8_t;
+    using s16 = std::int16_t;
+    using s32 = std::int32_t;
+    using s64 = std::int64_t;
+    using u8  = std::uint8_t;
+    using u16 = std::uint16_t;
+    using u32 = std::uint32_t;
+    using u64 = std::uint64_t;
+
+    struct array {
+        thing_type* type;
+        std::size_t size;
+    };
+
+    enum type { // NOLINT
+        S8 = 0,
+        S16,
+        S32,
+        S64,
+        U8,
+        U16,
+        U32,
+        U64,
+        Ptr,
+        Ref,
+        Array,
+
+        Count,
+    } type;
+    union value {
+        std::nullptr_t null = nullptr;
+        thing_type*    typeRef;
+        array          array;
+
+        value() = default;
+
+        value(thing_type* type)
+          : typeRef(type) {}
+
+        value(thing_type* type, std::size_t size)
+          : array({}) {
+            array.type = type;
+            array.size = size;
+        }
+    } value;
+
+    static constexpr thing_type_id INVALID_ID = std::numeric_limits<thing_type_id>::max();
+
+    thing_type_id id = INVALID_ID;
+
+    bool operator==(const thing_type& other) const {
+        if (type != other.type) return false;
+        switch (type) {
+        case S8:
+        case S16:
+        case S32:
+        case S64:
+        case U8:
+        case U16:
+        case U32:
+        case U64: return true;
+        case Ptr:
+        case Ref: return *value.typeRef == *other.value.typeRef;
+        case Array: return *value.array.type == *other.value.array.type && value.array.size == other.value.array.size;
+        case Count: break;
+        }
+        return false;
+    }
+
+    bool operator!=(const thing_type& other) const { return !this->operator==(other); }
+
+    static bool is_primitive(enum type type) {
+        switch (type) {
+        case S8:
+        case S16:
+        case S32:
+        case S64:
+        case U8:
+        case U16:
+        case U32:
+        case U64: return true;
+        case Ptr:
+        case Ref:
+        case Array: return false;
+        case Count: break;
+        }
+        throw std::runtime_error("unreachable");
+    }
+
+    static std::size_t primitive_size(enum type type) {
+        switch (type) {
+        case thing_type::S8: return sizeof(s8);
+        case thing_type::S16: return sizeof(s16);
+        case thing_type::S32: return sizeof(s32);
+        case thing_type::S64: return sizeof(s64);
+        case thing_type::U8: return sizeof(u8);
+        case thing_type::U16: return sizeof(u16);
+        case thing_type::U32: return sizeof(u32);
+        case thing_type::U64: return sizeof(u64);
+        case Ptr:
+        case Ref:
+        case Array: return 0;
+        case Count: break;
+        }
+        throw std::runtime_error("unreachable");
+    }
 };
 
-/**
- * @brief Returns data size of a thing.
- *
- * @param type Type of the thing.
- * @return The data size of the thing.
- */
-std::size_t thing_type_size(thing_t type);
+namespace detail {
 
-class bad_thing_access : public std::exception {
-public:
-    bad_thing_access()           = default;
-    ~bad_thing_access() override = default;
-
-    /**
-     * @brief Move constructor.
-     */
-    bad_thing_access(bad_thing_access&&) noexcept = default;
-
-    /**
-     * @brief Move constructor.
-     */
-    bad_thing_access& operator=(bad_thing_access&&) noexcept = default;
-
-    /**
-     * @brief Copy constructor.
-     */
-    bad_thing_access(const bad_thing_access&) = default;
-
-    /**
-     * @brief Copy constructor.
-     */
-    bad_thing_access& operator=(const bad_thing_access&) = default;
-public:
-    /**
-     * @brief Returns a C-style string describing the cause of the error.
-     *
-     * @return The cause of the error.
-     */
-    const char* what() const noexcept override { return "bad thing access"; }
+struct thing_type_hash {
+    std::size_t operator()(const thing_type& type) const {
+        std::size_t seed = std::hash<decltype(type.type)>{}(type.type);
+        switch (type.type) {
+        case thing_type::S8:
+        case thing_type::S16:
+        case thing_type::S32:
+        case thing_type::S64:
+        case thing_type::U8:
+        case thing_type::U16:
+        case thing_type::U32:
+        case thing_type::U64: return seed;
+        case thing_type::Ptr:
+        case thing_type::Ref: return furlang::utility::hash_combine(seed, thing_type_hash{}(*type.value.typeRef));
+        case thing_type::Array:
+            seed = furlang::utility::hash_combine(seed, thing_type_hash{}(*type.value.array.type));
+            seed = furlang::utility::hash_combine(seed,
+                std::hash<decltype(type.value.array.size)>{}(type.value.array.size));
+            return seed;
+        case thing_type::Count: break;
+        }
+        throw std::runtime_error("unreachable");
+    }
 };
 
+} // namespace detail
+
+class thing_type_store {
+public:
+    thing_type* insert(thing_type& type) {
+        if (auto it = m_typeMap.find(type); it != m_typeMap.end()) return m_map[type.id = it->second];
+        if (type.id == thing_type::INVALID_ID) type.id = m_counter++;
+
+        thing_type* ptr = m_arena.allocate<thing_type>(type);
+        m_map[type.id]  = ptr;
+        m_typeMap[type] = type.id;
+        return ptr;
+    }
+
+    thing_type* insert(const thing_type& type) {
+        if (auto it = m_typeMap.find(type); it != m_typeMap.end()) return m_map[it->second];
+
+        thing_type_id id  = m_counter++;
+        thing_type*   ptr = m_arena.allocate<thing_type>(type);
+        m_map[id]         = ptr;
+        m_typeMap[type]   = id;
+        return ptr;
+    }
+
+    thing_type* at(thing_type_id id) const {
+        if (auto it = m_map.find(id); it != m_map.end()) return it->second;
+        return nullptr;
+    }
+private:
+    furlang::arena                                                         m_arena;
+    std::unordered_map<thing_type_id, thing_type*>                         m_map;
+    std::unordered_map<thing_type, thing_type_id, detail::thing_type_hash> m_typeMap;
+    thing_type_id                                                          m_counter = 0;
+};
+
+template <template <typename> typename Allocator>
 class thing final {
     friend class executor;
-private:
-    /**
-     * @brief A private token for the private constructor.
-     *
-     * Also `rzecz` in Polish translates to `thing` I think.
-     */
-    struct rzecz {
-        explicit rzecz() = default;
+public:
+    using allocator_type = Allocator<std::byte>; /**< Allocator type. */
+public:
+    union array {
+        std::byte flat[];
+        struct {
+            std::size_t size;
+            std::byte*  data;
+        } dynamic;
     };
-public:
-    using nref_t = std::size_t; /**< Type of reference count. */
-
-    static constexpr thing_handle GENERATION_SIZE = 12; /**< Bit size of generation part in thing_handle. */
 public:
     /**
-     * @brief Private constructor.
+     * @brief Constructs a thing.
      *
-     * @param id
-     * @param type
-     * @param context
+     * @param type Thing type.
+     * @param allocator Allocator for the thing's data.
      */
-    thing(rzecz, thing_handle id, thing_t type, const context_p& context);
+    thing(const thing_type& type, const allocator_type& allocator = {})
+      : m_type(type), m_size(compute_size(type)), m_allocator(allocator) {
+        if (m_type.type == thing_type::Ref) return;
+        // TODO: Account for alignment
+        m_data = m_allocator.allocate(m_size);
+        std::memset(m_data, 0, m_size);
+    }
 
-    ~thing();
+    /**
+     * @brief Destructs a thing.
+     */
+    ~thing() {
+        if (m_type.type != thing_type::Ref && m_data != nullptr && m_size > 0) m_allocator.deallocate(m_data, m_size);
+    }
 
     /**
      * @brief Move constructor.
      */
-    thing(thing&&) noexcept;
+    thing(thing&& other) noexcept
+      : m_type(other.m_type), m_data(other.m_data), m_size(other.m_size), m_allocator(std::move(other.m_allocator)) {
+        other.m_type.type = thing_type::Count;
+        other.m_data      = nullptr;
+        other.m_size      = 0;
+    }
 
     /**
      * @brief Move constructor.
      */
-    thing& operator=(thing&&) noexcept;
+    thing& operator=(thing&& other) noexcept {
+        if (this == &other) return *this;
+        m_type            = other.m_type;
+        m_data            = other.m_data;
+        m_allocator       = std::move(other.m_allocator);
+        other.m_type.type = thing_type::Count;
+        other.m_data      = nullptr;
+        other.m_size      = 0;
+        return *this;
+    }
 
     thing(const thing&)            = delete;
     thing& operator=(const thing&) = delete;
 public:
     /**
-     * @brief Adds two things together.
+     * @brief Returns a clone of the thing.
      *
-     * @param lhs Left-hand-side thing.
-     * @param rhs Right-hand-side thing.
-     * @return Shared pointer to result thing.
+     * @return A clone of this thing.
      */
-    friend thing_p operator+(const thing_p& lhs, const thing_p& rhs);
-
-    /**
-     * @brief Subtracts two things together.
-     *
-     * @param lhs Left-hand-side thing.
-     * @param rhs Right-hand-side thing.
-     * @return Shared pointer to result thing.
-     */
-    friend thing_p operator-(const thing_p& lhs, const thing_p& rhs);
-
-    /**
-     * @brief Multiplies two things together.
-     *
-     * @param lhs Left-hand-side thing.
-     * @param rhs Right-hand-side thing.
-     * @return Shared pointer to result thing.
-     */
-    friend thing_p operator*(const thing_p& lhs, const thing_p& rhs);
-
-    /**
-     * @brief Divides two things together.
-     *
-     * @param lhs Left-hand-side thing.
-     * @param rhs Right-hand-side thing.
-     * @return Shared pointer to result thing.
-     */
-    friend thing_p operator/(const thing_p& lhs, const thing_p& rhs);
-
-    /**
-     * @brief Modulos two things together.
-     *
-     * @param lhs Left-hand-side thing.
-     * @param rhs Right-hand-side thing.
-     * @return Shared pointer to result thing.
-     */
-    friend thing_p operator%(const thing_p& lhs, const thing_p& rhs);
+    thing clone() const {
+        thing res(m_type, m_allocator);
+        switch (m_type.type) {
+        case thing_type::S8:
+        case thing_type::S16:
+        case thing_type::S32:
+        case thing_type::S64:
+        case thing_type::U8:
+        case thing_type::U16:
+        case thing_type::U32:
+        case thing_type::U64:
+        case thing_type::Ptr: std::memcpy(res.m_data, m_data, m_size); return std::move(res);
+        case thing_type::Array: copy_list(m_type, res.get<array>(), get<array>()); return std::move(res);
+        case thing_type::Ref: throw std::runtime_error("cannot clone references");
+        case thing_type::Count: break;
+        }
+        throw std::runtime_error("unreachable");
+    }
 public:
     /**
-     * @brief Returns a new thing.
+     * @brief Returns the thing's type.
      *
-     * @param context Furvm context.
-     * @param args Arguments to forward to the thing constructor.
-     * @return Shared pointer to the new thing.
+     * @return The type.
      */
-    template <typename... Args,
-        typename = std::enable_if_t<std::is_constructible_v<thing, rzecz, thing_handle, Args..., const context_p&>>>
-    static thing_p create(const context_p& context, Args&&... args) {
-        thing_handle id = context->m_things.size();
-        if (!context->m_deadThings.empty()) {
-            id = context->m_deadThings.front();
-            context->m_deadThings.pop();
-            id += 1 << GENERATION_SIZE;
-        }
-        thing_handle idx = id & ((1ULL << ((sizeof(id) * 8) - GENERATION_SIZE)) - 1);
+    constexpr thing_type type() const { return m_type; }
 
-        auto th = std::make_shared<thing>(rzecz{}, id, std::forward<Args>(args)..., context);
-        context->m_things.emplace(context->m_things.begin() + idx, th);
-        return std::move(th);
+    /**
+     * @brief Returns the thing's true type.
+     *
+     * If the thing is a reference, returns the referenced type.
+     *
+     * @return The true type.
+     */
+    constexpr thing_type true_type() const { return (m_type.type == thing_type::Ref) ? *m_type.value.typeRef : m_type; }
+
+    /**
+     * @brief Checks if the thing is of a specified type.
+     *
+     * Compares the true type.
+     *
+     * @param type Type to compare.
+     * @return true if the types match.
+     */
+    constexpr bool is(enum thing_type::type type) const { return true_type().type == type; }
+public:
+    /**
+     * @brief Returns a raw data pointer.
+     *
+     * @return The data pointer.
+     */
+    void* raw() { return m_data; }
+
+    /**
+     * @brief Returns a raw data pointer.
+     *
+     * @return The data pointer.
+     */
+    const void* raw() const { return m_data; }
+public:
+    /**
+     * @brief Returns the thing's value.
+     *
+     * @return The value.
+     */
+    template <typename T>
+    T& get() {
+        if (compute_size_na(m_type) != sizeof(T)) throw bad_thing_access();
+        return *std::launder(reinterpret_cast<T*>(m_data));
     }
 
     /**
-     * @brief Returns a clone of the thing.
-     *
-     * @param thing Thing to clone.
-     * @return Shared pointer to a clone of the thing.
-     */
-    static thing_p clone(const thing_p& thing);
-public:
-    /**
-     * @brief Returns an int32 value from this thing.
+     * @brief Returns the thing's value.
      *
      * @return The value.
      */
-    std::int32_t& int32();
-
-    /**
-     * @brief Returns an int32 value from this thing.
-     *
-     * @return The value.
-     */
-    const std::int32_t& int32() const;
+    template <typename T>
+    const T& get() const {
+        if (compute_size_na(m_type) != sizeof(T)) throw bad_thing_access();
+        return *std::launder(reinterpret_cast<const T*>(m_data));
+    }
 public:
     /**
-     * @brief Increments reference count of this thing by one.
-     */
-    void add_reference() { ++m_refCount; }
-
-    /**
-     * @brief Decrements reference count of this thing by one.
-     */
-    void remove_reference() { --m_refCount; }
-
-    /**
-     * @brief Returns reference count of this thing.
+     * @brief Returns a sum of two things.
      *
-     * @return The reference count.
+     * @param rhs Thing to sum with this thing (right-hand-side).
+     * @return The sum.
      */
-    constexpr nref_t reference_count() const { return m_refCount; }
+    thing add(const thing& rhs) const { return binary_op(rhs, std::plus<>{}); }
+
+    /**
+     * @brief Returns a difference of two things.
+     *
+     * @param rhs Thing to subtract from this thing (right-hand-side).
+     * @return The sum.
+     */
+    thing sub(const thing& rhs) const { return binary_op(rhs, std::minus<>{}); }
+
+    /**
+     * @brief Returns a product of two things.
+     *
+     * @param rhs Thing to multiply with this thing (right-hand-side).
+     * @return The product.
+     */
+    thing mul(const thing& rhs) const { return binary_op(rhs, std::multiplies<>{}); }
+
+    /**
+     * @brief Returns a quotient of two things.
+     *
+     * @param rhs Thing to divide this thing by (right-hand-side).
+     * @return The quotient.
+     */
+    thing div(const thing& rhs) const { return binary_op(rhs, std::divides<>{}); }
+
+    /**
+     * @brief Returns a remainder of two things.
+     *
+     * @param rhs Thing to divide this thing by (right-hand-side).
+     * @return The remainder.
+     */
+    thing mod(const thing& rhs) const { return binary_op(rhs, std::modulus<>{}); }
+
+    /**
+     * @brief Compares two things for equality.
+     *
+     * @param rhs Thing to compare this thing with (right-hand-side).
+     * @return A boolean result of the comparison in a thing form.
+     */
+    thing equals(const thing& rhs) const { return binary_op(rhs, std::equal_to<>{}); }
+
+    /**
+     * @brief Compares two things for inequality.
+     *
+     * @param rhs Thing to compare this thing with (right-hand-side).
+     * @return A boolean result of the comparison in a thing form.
+     */
+    thing not_equals(const thing& rhs) const { return binary_op(rhs, std::not_equal_to<>{}); }
+
+    /**
+     * @brief Compares if this thing is less than an another thing.
+     *
+     * @param rhs The another thing.
+     * @return A boolean result of the comparison in a thing form.
+     */
+    thing less_than(const thing& rhs) const { return binary_op(rhs, std::less<>{}); }
+
+    /**
+     * @brief Compares if this thing is greater than an another thing.
+     *
+     * @param rhs The another thing.
+     * @return A boolean result of the comparison in a thing form.
+     */
+    thing greater_than(const thing& rhs) const { return binary_op(rhs, std::greater<>{}); }
+
+    /**
+     * @brief Compares if this thing is less than or equal to an another thing.
+     *
+     * @param rhs The another thing.
+     * @return A boolean result of the comparison in a thing form.
+     */
+    thing less_equals(const thing& rhs) const { return binary_op(rhs, std::less_equal<>{}); }
+
+    /**
+     * @brief Compares if this thing is greater than or equal to an another thing.
+     *
+     * @param rhs The another thing.
+     * @return A boolean result of the comparison in a thing form.
+     */
+    thing greater_equals(const thing& rhs) const { return binary_op(rhs, std::greater_equal<>{}); }
+public:
+    /**
+     * @brief Returns a largest integer value of the thing.
+     *
+     * @return The integer value.
+     */
+    thing_type::s64 integer() const {
+        switch (true_type().type) {
+        case thing_type::S8: return get<thing_type::s8>();
+        case thing_type::S16: return get<thing_type::s16>();
+        case thing_type::S32: return get<thing_type::s32>();
+        case thing_type::S64: return get<thing_type::s64>();
+        case thing_type::U8: return get<thing_type::u8>();
+        case thing_type::U16: return get<thing_type::u16>();
+        case thing_type::U32: return get<thing_type::u32>();
+        case thing_type::U64: return get<thing_type::u64>();
+        default: throw std::runtime_error("unreachable");
+        }
+    }
+
+    void resize(thing_type::u64 newSize) {
+        if (!is(thing_type::Array)) throw bad_thing_access();
+        if (true_type().value.array.size > 0) throw std::runtime_error("cannot resize a static array");
+
+        auto& array = get<union array>();
+        if (newSize < 0 || newSize == array.dynamic.size) return;
+        std::size_t innerSize = compute_size_na(*true_type().value.array.type);
+        std::byte*  newData   = new std::byte[innerSize * newSize];
+        std::memcpy(newData,
+            array.dynamic.data,
+            innerSize * std::min(static_cast<thing_type::u64>(array.dynamic.size), newSize));
+        array.dynamic.size = newSize;
+        delete[] array.dynamic.data;
+        array.dynamic.data = newData;
+    }
+
+    thing at(thing_type::u64 index) const {
+        if (!is(thing_type::Array)) throw bad_thing_access();
+
+        std::size_t elementSize = compute_size_na(*m_type.value.array.type);
+        if (m_type.value.array.size == 0) {
+            auto& array = get<union array>();
+            if (index < 0 || index >= array.dynamic.size) throw std::out_of_range("index out of range");
+            thing ref  = { { thing_type::Ref, m_type.value.array.type }, m_allocator };
+            ref.m_data = array.dynamic.data + (index * elementSize);
+            return ref;
+        }
+
+        std::byte* data = reinterpret_cast<array*>(m_data)->flat;
+        if (index < 0 || index >= m_type.value.array.size) throw std::out_of_range("index out of range");
+        thing ref  = { { thing_type::Ref, m_type.value.array.type }, m_allocator };
+        ref.m_data = data + (index * elementSize);
+        return ref;
+    }
+
+    thing_type::u64 length() const {
+        if (!is(thing_type::Array)) throw bad_thing_access();
+        return true_type().value.array.size == 0 ? get<array>().dynamic.size : true_type().value.array.size;
+    }
+
+    template <typename T, typename = std::enable_if_t<std::is_integral_v<T>>>
+    T cast_to() const {
+        return visit_primitive([](auto value) { return static_cast<T>(value); });
+    }
+
+    /**
+     * @brief Changes reference thing's referenced thing.
+     *
+     * Yes.
+     *
+     * @param thing Thing.
+     */
+    void reference(const thing& thing) {
+        if (m_type.type != thing_type::Ref || *m_type.value.typeRef != thing.type()) throw bad_thing_access();
+        m_data = thing.m_data;
+    }
+
+    /**
+     * @brief Self-explainatory.
+     *
+     * TODO: Document
+     */
+    void assign(thing&& thing) {
+        class thing rhs = std::move(thing);
+        if (true_type() != rhs.true_type()) throw std::runtime_error("thing type mismatch");
+        // TODO: Move this to another function
+        switch (true_type().type) {
+        case thing_type::S8:
+        case thing_type::S16:
+        case thing_type::S32:
+        case thing_type::S64:
+        case thing_type::U8:
+        case thing_type::U16:
+        case thing_type::U32:
+        case thing_type::U64: std::memcpy(m_data, rhs.m_data, m_size); return;
+        case thing_type::Ptr:
+        case thing_type::Ref:
+        case thing_type::Array: throw std::runtime_error("unimplemented");
+        case thing_type::Count: break;
+        }
+        throw std::runtime_error("unreachable");
+    }
 private:
-    thing_handle m_id;
-    thing_t      m_type;
-    context_p    m_context;
+    static void copy_list(const thing_type& arrayType, array& dst, const array& src) {
+        if (arrayType.type != thing_type::Array || arrayType.value.array.type == nullptr)
+            throw std::runtime_error("invalid type");
 
-    nref_t m_refCount = 0;
-    void*  m_data     = nullptr;
+        const auto& innerType   = *arrayType.value.array.type;
+        std::size_t elementSize = compute_size_na(innerType);
+
+        std::byte*       data    = nullptr;
+        const std::byte* srcData = nullptr;
+        std::size_t      size    = 0;
+        if (arrayType.value.array.size == 0) {
+            size = dst.dynamic.size = src.dynamic.size;
+            if (dst.dynamic.size < 0) {
+                dst.dynamic.data = nullptr;
+                return;
+            }
+
+            srcData = src.dynamic.data;
+            data = dst.dynamic.data = new std::byte[dst.dynamic.size];
+        } else {
+            data    = dst.flat;
+            srcData = src.flat;
+            size    = arrayType.value.array.size;
+        }
+
+        switch (innerType.type) {
+        case thing_type::S8:
+        case thing_type::S16:
+        case thing_type::S32:
+        case thing_type::S64:
+        case thing_type::U8:
+        case thing_type::U16:
+        case thing_type::U32:
+        case thing_type::U64:
+        case thing_type::Ptr:
+        case thing_type::Ref: std::memcpy(dst.flat, src.flat, size); return;
+        case thing_type::Array:
+            for (std::size_t i = 0; i < size; ++i) {
+                copy_list(*innerType.value.array.type,
+                    *std::launder(reinterpret_cast<array*>(data + (i * elementSize))),
+                    *std::launder(reinterpret_cast<const array*>(srcData + (i * elementSize))));
+            }
+            return;
+        case thing_type::Count: break;
+        }
+        throw std::runtime_error("unreachable");
+    }
+private:
+    static std::size_t compute_size_na(const thing_type& type) {
+        switch (type.type) {
+        case thing_type::S8: return sizeof(thing_type::s8);
+        case thing_type::S16: return sizeof(thing_type::s16);
+        case thing_type::S32: return sizeof(thing_type::s32);
+        case thing_type::S64: return sizeof(thing_type::s64);
+        case thing_type::U8: return sizeof(thing_type::u8);
+        case thing_type::U16: return sizeof(thing_type::u16);
+        case thing_type::U32: return sizeof(thing_type::u32);
+        case thing_type::U64: return sizeof(thing_type::u64);
+        case thing_type::Ptr: return sizeof(void*);
+        case thing_type::Ref: return compute_size_na(*type.value.typeRef);
+        case thing_type::Array:
+            return type.value.array.size == 0 ? sizeof(array)
+                                              : compute_size_na(*type.value.array.type) * type.value.array.size;
+        case thing_type::Count: break;
+        }
+
+        throw std::runtime_error("unreachable");
+    }
+
+    // NOTE: Align to 4 bytes
+    static std::size_t compute_size(const thing_type& type) { return (compute_size_na(type) + 3) & ~3; }
+private:
+    template <typename Func>
+    decltype(auto) visit_primitive(Func&& func) const {
+        switch (true_type().type) {
+        case thing_type::S8: return std::forward<Func>(func)(get<thing_type::s8>());
+        case thing_type::S16: return std::forward<Func>(func)(get<thing_type::s16>());
+        case thing_type::S32: return std::forward<Func>(func)(get<thing_type::s32>());
+        case thing_type::S64: return std::forward<Func>(func)(get<thing_type::s64>());
+        case thing_type::U8: return std::forward<Func>(func)(get<thing_type::u8>());
+        case thing_type::U16: return std::forward<Func>(func)(get<thing_type::u16>());
+        case thing_type::U32: return std::forward<Func>(func)(get<thing_type::u32>());
+        case thing_type::U64: return std::forward<Func>(func)(get<thing_type::u64>());
+        default: throw bad_thing_access();
+        }
+    }
+
+    template <typename Op>
+    thing binary_op(const thing& rhs, const Op& op) const {
+        if (thing_type::is_primitive(true_type().type) && thing_type::is_primitive(true_type().type)) {
+            static constexpr enum thing_type::type promotions[8 * 8] = {
+                // S8
+                thing_type::S8,
+                thing_type::S16,
+                thing_type::S32,
+                thing_type::S64,
+                thing_type::S16,
+                thing_type::S16,
+                thing_type::S32,
+                thing_type::U64,
+                // S16
+                thing_type::S16,
+                thing_type::S16,
+                thing_type::S32,
+                thing_type::S64,
+                thing_type::S16,
+                thing_type::S16,
+                thing_type::S32,
+                thing_type::U64,
+                // S32
+                thing_type::S32,
+                thing_type::S32,
+                thing_type::S32,
+                thing_type::S64,
+                thing_type::S32,
+                thing_type::S32,
+                thing_type::U32,
+                thing_type::U64,
+                // S64
+                thing_type::S64,
+                thing_type::S64,
+                thing_type::S64,
+                thing_type::S64,
+                thing_type::S64,
+                thing_type::S64,
+                thing_type::S64,
+                thing_type::U64,
+                // U8
+                thing_type::S16,
+                thing_type::S16,
+                thing_type::S32,
+                thing_type::S64,
+                thing_type::U8,
+                thing_type::U16,
+                thing_type::U32,
+                thing_type::U64,
+                // U16
+                thing_type::S16,
+                thing_type::S16,
+                thing_type::S32,
+                thing_type::S64,
+                thing_type::U16,
+                thing_type::U16,
+                thing_type::U32,
+                thing_type::U64,
+                // U32
+                thing_type::S32,
+                thing_type::S32,
+                thing_type::U32,
+                thing_type::S64,
+                thing_type::U32,
+                thing_type::U32,
+                thing_type::U32,
+                thing_type::U64,
+                // U64
+                thing_type::U64,
+                thing_type::U64,
+                thing_type::U64,
+                thing_type::U64,
+                thing_type::U64,
+                thing_type::U64,
+                thing_type::U64,
+                thing_type::U64,
+            };
+
+            enum thing_type::type resultType = promotions[true_type().type + (rhs.true_type().type * 8)];
+
+            thing res = { thing_type{ resultType }, m_allocator };
+            switch (resultType) {
+            case thing_type::S8:
+                res.get<thing_type::s8>() = Op{}(cast_to<thing_type::s8>(), rhs.cast_to<thing_type::s8>());
+                return res;
+            case thing_type::S16:
+                res.get<thing_type::s16>() = Op{}(cast_to<thing_type::s16>(), rhs.cast_to<thing_type::s16>());
+                return res;
+            case thing_type::S32:
+                res.get<thing_type::s32>() = Op{}(cast_to<thing_type::s32>(), rhs.cast_to<thing_type::s32>());
+                return res;
+            case thing_type::S64:
+                res.get<thing_type::s64>() = Op{}(cast_to<thing_type::s64>(), rhs.cast_to<thing_type::s64>());
+                return res;
+            case thing_type::U8:
+                res.get<thing_type::u8>() = Op{}(cast_to<thing_type::u8>(), rhs.cast_to<thing_type::u8>());
+                return res;
+            case thing_type::U16:
+                res.get<thing_type::u16>() = Op{}(cast_to<thing_type::u16>(), rhs.cast_to<thing_type::u16>());
+                return res;
+            case thing_type::U32:
+                res.get<thing_type::u32>() = Op{}(cast_to<thing_type::u32>(), rhs.cast_to<thing_type::u32>());
+                return res;
+            case thing_type::U64:
+                res.get<thing_type::u64>() = Op{}(cast_to<thing_type::u64>(), rhs.cast_to<thing_type::u64>());
+                return res;
+            case thing_type::Ptr: // TODO: Pointer arithmetics
+            case thing_type::Ref:
+            case thing_type::Array:
+            case thing_type::Count: break;
+            }
+            throw std::runtime_error("unreachable");
+        }
+
+        throw std::runtime_error("unexpected operation");
+    }
+private:
+    thing_type  m_type;
+    std::size_t m_size;
+    std::byte*  m_data;
+
+    allocator_type m_allocator;
 };
 
 } // namespace furvm

furvm/include/furvm/thing_allocator.hpp

@@ -0,0 +1,111 @@
+#ifndef FURVM_THING_ALLOCATOR_HPP
+#define FURVM_THING_ALLOCATOR_HPP
+
+#include "furlang/arena.hpp"
+
+#include <vector>
+
+namespace furvm {
+
+template <typename T>
+class thing_allocator {
+    template <typename>
+    friend class thing_allocator;
+
+    using dead_things = std::vector<std::pair<T*, std::size_t>>;
+public:
+    using value_type = T; /**< Value type. */
+public:
+    /**
+     * @brief Constructs a thing allocator.
+     *
+     * @param arena Base arena allocator.
+     */
+    explicit thing_allocator(furlang::arena& arena) noexcept
+      : m_arena(&arena), m_deadThings(std::make_shared<dead_things>()) {}
+
+    /**
+     * @brief Move constructor.
+     */
+    template <typename U>
+    thing_allocator(thing_allocator<U>&& other) noexcept
+      : m_arena(std::move(other.m_arena)), m_deadThings(std::move(other.m_deadThings)) {}
+
+    /**
+     * @brief Move constructor.
+     */
+    template <typename U>
+    thing_allocator& operator=(thing_allocator<U>&& other) noexcept {
+        if (this == &other) return *this;
+        m_arena      = std::move(other.m_arena);
+        m_deadThings = std::move(other.m_deadThings);
+        return *this;
+    }
+
+    /**
+     * @brief Copy constructor.
+     */
+    template <typename U>
+    thing_allocator(const thing_allocator<U>& other) noexcept
+      : m_arena(other.m_arena), m_deadThings(other.m_deadThings) {}
+
+    /**
+     * @brief Copy constructor.
+     */
+    template <typename U>
+    thing_allocator& operator=(const thing_allocator<U>& other) noexcept {
+        if (this == &other) return *this;
+        m_arena      = other.m_arena;
+        m_deadThings = other.m_deadThings;
+        return *this;
+    }
+public:
+    /**
+     * @brief Returns a free chunk of memory.
+     *
+     * @param count Count of the things that must fit inside the chunk.
+     * @return The chunk.
+     */
+    [[nodiscard]] T* allocate(std::size_t count = 1) {
+        for (auto it = m_deadThings->begin(); it != m_deadThings->end(); ++it) {
+            if (it->second != count) continue;
+            T* data = it->first;
+            m_deadThings->erase(it);
+            return data;
+        }
+        return m_arena->allocate<T>(count);
+    }
+
+    /**
+     * @brief Recycles the pointer.
+     */
+    void deallocate(T* ptr, std::size_t count) noexcept { m_deadThings->emplace_back(ptr, count); }
+public:
+    /**
+     * @brief Compares two thing allocators for equality.
+     *
+     * @return true if the two things are equal.
+     */
+    template <typename U>
+    bool operator==(const thing_allocator<U>& other) const noexcept {
+        return m_arena == other.m_arena && m_deadThings == other.m_deadThings;
+    }
+
+    /**
+     * @brief Compares two thing allocators for inequality.
+     *
+     * @return true if the two things are not equal.
+     */
+    template <typename U>
+    bool operator!=(const thing_allocator<U>& other) const noexcept {
+        return m_arena != other.m_arena || m_deadThings != other.m_deadThings;
+    }
+private:
+    furlang::arena* m_arena;
+
+    std::shared_ptr<dead_things> m_deadThings;
+};
+
+} // namespace furvm
+
+#endif // FURVM_THING_ALLOCATOR_HPP

furvm/src/context.cpp

@@ -1,16 +0,0 @@
-#include "furvm/context.hpp"
-
-#include "furvm/thing.hpp" // IWYU pragma: keep
-
-namespace furvm {
-
-context::context() {}
-
-void context::collect() {
-    for (auto& ref : m_things) {
-        if (ref->reference_count() != 0) continue;
-        ref = nullptr;
-    }
-}
-
-} // namespace furvm

furvm/src/detail/serialization.cpp

@@ -0,0 +1,127 @@
+#include "furvm/detail/serialization.hpp"
+
+#include <istream>
+#include <ostream>
+
+namespace furvm::detail {
+
+namespace {
+
+template <typename T, std::size_t... I>
+void serialize_integral_impl(std::ostream& os, std::make_unsigned_t<T> u_value, std::index_sequence<I...>) {
+    ((os << static_cast<char>((u_value >> (I * 8)) & 0xFF)), ...);
+}
+
+template <typename T, std::size_t... I>
+void load_integral_impl(const char* bs, std::make_unsigned_t<T>& u_value, std::index_sequence<I...>) {
+    using UnsignedT = std::make_unsigned_t<T>;
+    ((u_value |= (static_cast<UnsignedT>(static_cast<std::uint8_t>(bs[I])) << (I * 8))), ...);
+}
+
+template <typename T>
+std::ostream& serialize_integral(std::ostream& os, T value) {
+    static_assert(std::is_integral_v<T>, "Type must be an integral type.");
+    using UnsignedT = std::make_unsigned_t<T>;
+
+    serialize_integral_impl<T>(os, static_cast<UnsignedT>(value), std::make_index_sequence<sizeof(T)>{});
+    return os;
+}
+
+template <typename T>
+std::istream& load_integral(std::istream& is, T& value) {
+    static_assert(std::is_integral_v<T>, "Type must be an integral type.");
+
+    char bs[sizeof(T)];
+    if (!is.read(bs, sizeof(T))) {
+        return is;
+    }
+
+    using UnsignedT = std::make_unsigned_t<T>;
+    UnsignedT uVal  = 0;
+
+    load_integral_impl<T>(bs, uVal, std::make_index_sequence<sizeof(T)>{});
+
+    value = static_cast<T>(uVal);
+    return is;
+}
+
+} // namespace
+
+std::ostream& serialize(std::ostream& os, std::int8_t value) {
+    return serialize_integral(os, value);
+}
+
+std::ostream& serialize(std::ostream& os, std::int16_t value) {
+    return serialize_integral(os, value);
+}
+
+std::ostream& serialize(std::ostream& os, std::int32_t value) {
+    return serialize_integral(os, value);
+}
+
+std::ostream& serialize(std::ostream& os, std::int64_t value) {
+    return serialize_integral(os, value);
+}
+
+std::ostream& serialize(std::ostream& os, std::uint8_t value) {
+    return serialize_integral(os, value);
+}
+
+std::ostream& serialize(std::ostream& os, std::uint16_t value) {
+    return serialize_integral(os, value);
+}
+
+std::ostream& serialize(std::ostream& os, std::uint32_t value) {
+    return serialize_integral(os, value);
+}
+
+std::ostream& serialize(std::ostream& os, std::uint64_t value) {
+    return serialize_integral(os, value);
+}
+
+std::ostream& serialize(std::ostream& os, const std::string& value) {
+    return serialize(os, static_cast<std::uint16_t>(value.size()))
+        .write(value.data(), static_cast<std::streamsize>(value.size()));
+}
+
+std::istream& load(std::istream& is, std::int8_t& value) {
+    return load_integral(is, value);
+}
+
+std::istream& load(std::istream& is, std::int16_t& value) {
+    return load_integral(is, value);
+}
+
+std::istream& load(std::istream& is, std::int32_t& value) {
+    return load_integral(is, value);
+}
+
+std::istream& load(std::istream& is, std::int64_t& value) {
+    return load_integral(is, value);
+}
+
+std::istream& load(std::istream& is, std::uint8_t& value) {
+    return load_integral(is, value);
+}
+
+std::istream& load(std::istream& is, std::uint16_t& value) {
+    return load_integral(is, value);
+}
+
+std::istream& load(std::istream& is, std::uint32_t& value) {
+    return load_integral(is, value);
+}
+
+std::istream& load(std::istream& is, std::uint64_t& value) {
+    return load_integral(is, value);
+}
+
+std::istream& load(std::istream& is, std::string& value) {
+    std::uint16_t length = 0;
+    load(is, length);
+
+    value.resize(length);
+    return is.read(value.data(), static_cast<std::streamsize>(length));
+}
+
+} // namespace furvm::detail

furvm/src/executor.cpp

@@ -7,33 +7,85 @@
 #include "furvm/instruction.hpp"
 #include "furvm/thing.hpp"
 
+#include <cassert>
 #include <cstdint>
 #include <stdexcept>
+#include <utility>
+#include <vector>
 
 namespace furvm {
 
-executor::executor(egzekutor, executor_handle id, const context_p& context)
-  : m_id(id), m_context(context) {}
-
-executor::~executor() {
-    m_context->m_executors[m_id] = nullptr;
+thing_type executor::thing_type_impl(mod_h mod, mod_type type) const {
+    while (type.type == mod_type::Import) {
+        auto imprt = std::move(type.value.imprt);
+        mod        = m_context->at(imprt.modId);
+        type       = *mod->type_at(imprt.typeId);
+    }
+    switch (static_cast<enum thing_type::type>(type.type)) {
+    case thing_type::S8:
+    case thing_type::S16:
+    case thing_type::S32:
+    case thing_type::S64:
+    case thing_type::U8:
+    case thing_type::U16:
+    case thing_type::U32:
+    case thing_type::U64: return { static_cast<enum thing_type::type>(type.type) };
+    case thing_type::Ptr: return { thing_type::Ptr, thing_type(mod, *mod->type_at(type.value.typeRef)) };
+    case thing_type::Array: {
+        return { static_cast<enum thing_type::type>(type.type),
+            { thing_type(mod, *mod->type_at(type.value.array.typeId)), type.value.array.size } };
+    }
+    default: throw std::runtime_error("invalid thing type");
+    }
 }
 
-executor_p executor::create(const context_p& context) {
-    auto ex = std::make_shared<executor>(egzekutor{}, context->m_executors.size(), context);
-    context->m_executors.push_back(ex);
-    return std::move(ex);
+thing_type* executor::thing_type(const mod_h& mod, const mod_type& type) const {
+    struct thing_type thingType = thing_type_impl(mod, type);
+    return m_context->thing_type_store().insert(thingType);
 }
 
-void executor::push_frame(const function_p& function) {
-    if (function->type() != function_t::Normal) return;
-    m_frames.emplace((struct executor::frame){ function->mod(), function->position(), m_stack.size() });
+void executor::push_frame(const mod_h& mod, function function) {
+    mod_h modInst = mod;
+    while (function.type() == function_t::Import) {
+        modInst  = m_context->at(function.imp().mod);
+        function = *modInst->function_at(function.imp().function);
+    }
+
+    auto                 signature = function.signature();
+    std::vector<thing_h> args;
+    args.reserve(signature.params.size());
+    for (const auto& param : signature.params) {
+        auto arg = pop_thing();
+        if (arg->type() != *thing_type(mod, *param)) throw std::runtime_error("function argument type mismatch");
+        args.push_back(std::move(arg));
+    }
+
+    struct thing_type* returnType = nullptr;
+    if (function.signature().returnType.has_value())
+        returnType = thing_type(mod, *function.signature().returnType.value()); // NOLINT
+
+    switch (function.type()) {
+    case function_t::Normal: {
+        m_frames.emplace(
+            (struct executor::frame){ mod, function.position(), m_stack.size(), returnType, std::move(args) });
+    } break;
+    case function_t::Native: {
+        m_frames.emplace((struct executor::frame){ mod, 0, m_stack.size(), returnType, std::move(args) });
+        modInst->get_native_function(function.native())(*this);
+        pop_frame();
+    } break;
+    default: throw std::runtime_error("unexpected function type");
+    }
 }
 
 struct executor::frame executor::pop_frame() {
     if (m_frames.empty()) throw stack_underflow();
     struct executor::frame frame = m_frames.top();
     m_frames.pop();
+    thing_h returnValue;
+    if (frame.returnType != nullptr) returnValue = pop_thing();
+    if (m_stack.size() != frame.stackBase) throw std::runtime_error("unexhausted stack");
+    if (frame.returnType != nullptr) push_thing(std::move(returnValue));
     return frame;
 }
 
@@ -41,52 +93,37 @@ struct executor::frame executor::frame() const {
     return m_frames.top();
 }
 
-void executor::push_thing(const thing_p& thing) {
-    thing->add_reference();
-    m_stack.push(thing);
+thing_h executor::push_thing(::furvm::thing<>&& thing) {
+    return m_stack.emplace(m_context->emplace_thing(std::move(thing)));
 }
 
-void executor::push_thing(thing_p&& thing) {
-    thing->add_reference();
-    m_stack.push(std::move(thing));
-}
-
-thing_p executor::pop_thing() {
+thing_h executor::pop_thing() {
     if (m_frames.top().stackBase >= m_stack.size()) throw stack_underflow();
-    thing_p top = std::move(m_stack.top());
+    thing_h top = std::move(m_stack.top());
     m_stack.pop();
-    top->remove_reference();
-    return top;
+    return std::move(top);
 }
 
-thing_p executor::thing() const {
+thing_h executor::thing() const {
     if (m_frames.top().stackBase >= m_stack.size()) throw stack_underflow();
     return m_stack.top();
 }
 
-void executor::store_thing(variable_t variable, const thing_p& thing) {
+void executor::store_thing(variable_t variable, const thing_h& thing) {
     auto& frame = m_frames.top();
-    frame.variables.resize(variable + 1);
-    if (frame.variables[variable] != nullptr) {
-        frame.variables[variable]->remove_reference();
-    }
+    if (frame.variables.size() <= variable) frame.variables.resize(variable + 1);
     frame.variables[variable] = thing;
-    thing->add_reference();
 }
 
-void executor::store_thing(variable_t variable, thing_p&& thing) {
+void executor::store_thing(variable_t variable, thing_h&& thing) {
     auto& frame = m_frames.top();
-    frame.variables.resize(variable + 1);
-    if (frame.variables[variable] != nullptr) {
-        frame.variables[variable]->remove_reference();
-    }
-    thing->add_reference();
+    if (frame.variables.size() <= variable) frame.variables.resize(variable + 1);
     frame.variables[variable] = std::move(thing);
 }
 
-thing_p executor::load_thing(variable_t variable) const {
+thing_h executor::load_thing(variable_t variable) const {
     const auto& frame = m_frames.top();
-    return frame.variables[variable];
+    return { frame.variables[variable] };
 }
 
 void executor::step() {
@@ -94,13 +131,66 @@ void executor::step() {
 
     struct frame& frame = m_frames.top();
 
-    instruction_t instr = static_cast<instruction_t>(frame.mod->byte(frame.position++));
+    instruction_t instr = static_cast<instruction_t>((*frame.mod).byte(frame.position++));
     switch (instr) {
     case instruction_t::NoOperation: break;
-    case instruction_t::PushB2I: {
-        auto thing     = thing::create(m_context, thing_t::Int32);
-        thing->int32() = frame.mod->byte(frame.position++);
-        push_thing(std::move(thing));
+    case instruction_t::PushS8: {
+        push_thing({ (struct thing_type){ thing_type::S8 }, m_context->thing_alloc() })->get<thing_type::s8>() =
+            static_cast<thing_type::s8>(frame.mod->byte(frame.position++));
+    } break;
+    case instruction_t::PushU8: {
+        push_thing({ (struct thing_type){ thing_type::U8 }, m_context->thing_alloc() })->get<thing_type::u8>() =
+            static_cast<thing_type::u8>(frame.mod->byte(frame.position++));
+    } break;
+    case instruction_t::PushS16: {
+        thing_type::u16 value = frame.mod->byte(frame.position++);
+        value                |= static_cast<thing_type::u16>(frame.mod->byte(frame.position++) << 8);
+        push_thing({ (struct thing_type){ thing_type::S16 }, m_context->thing_alloc() })->get<thing_type::s16>() =
+            static_cast<thing_type::s16>(value);
+    } break;
+    case instruction_t::PushU16: {
+        thing_type::u16 value = frame.mod->byte(frame.position++);
+        value                |= static_cast<thing_type::u16>(frame.mod->byte(frame.position++) << 8);
+        push_thing({ (struct thing_type){ thing_type::U16 }, m_context->thing_alloc() })->get<thing_type::u16>() =
+            value;
+    } break;
+    case instruction_t::PushS32: {
+        push_thing({ (struct thing_type){ thing_type::S32 }, m_context->thing_alloc() })->get<thing_type::s32>() =
+            static_cast<thing_type::s32>(frame.mod->byte(frame.position++));
+    } break;
+    case instruction_t::PushU32: {
+        push_thing({ (struct thing_type){ thing_type::U32 }, m_context->thing_alloc() })->get<thing_type::u32>() =
+            static_cast<thing_type::u32>(frame.mod->byte(frame.position++));
+    } break;
+    case instruction_t::Array: {
+        mod_type_id typeId = static_cast<mod_type_id>(frame.mod->byte(frame.position)) |
+                             (static_cast<mod_type_id>(frame.mod->byte(frame.position + 1)) << 8) |
+                             (static_cast<mod_type_id>(frame.mod->byte(frame.position + 2)) << 16) |
+                             (static_cast<mod_type_id>(frame.mod->byte(frame.position + 3)) << 24);
+        frame.position    += 4;
+
+        const auto& type = *thing_type(frame.mod, *frame.mod->type_at(typeId));
+        if (type.type != thing_type::Array || type.value.array.type == nullptr || type.value.array.type == &type)
+            throw std::runtime_error("invalid array type");
+
+        auto array = push_thing({ type, m_context->thing_alloc() });
+
+        if (type.value.array.size == 0) {
+            auto         sizeThing = pop_thing();
+            std::int64_t size      = sizeThing->integer();
+            array->resize(size);
+        }
+    } break;
+    case instruction_t::Get: {
+        auto index = pop_thing();
+        auto array = pop_thing();
+        push_thing(array->at(index->integer()));
+    } break;
+    case instruction_t::Set: {
+        auto element = pop_thing();
+        auto index   = pop_thing();
+        auto array   = pop_thing();
+        array->at(index->integer()).assign(std::move(element->clone()));
     } break;
     case instruction_t::Drop: {
         pop_thing();
@@ -108,68 +198,143 @@ void executor::step() {
     case instruction_t::Duplicate: {
         push_thing(thing());
     } break;
+    case instruction_t::Swap: {
+        auto thing1 = pop_thing();
+        auto thing2 = pop_thing();
+        push_thing(std::move(thing1));
+        push_thing(std::move(thing2));
+    } break;
     case instruction_t::Clone: {
-        push_thing(std::move(thing::clone(thing())));
+        push_thing(std::move(thing()->clone()));
+    } break;
+    case instruction_t::Reference: {
+        auto thing = pop_thing();
+        push_thing({ (struct thing_type){ thing_type::Ref, m_context->thing_type_store().insert(thing->type()) },
+                       m_context->thing_alloc() })
+            ->reference(*thing);
     } break;
     case instruction_t::Add: {
         auto rhs = pop_thing();
         auto lhs = pop_thing();
-        push_thing(lhs + rhs);
+        push_thing(lhs->add(*rhs));
     } break;
     case instruction_t::Sub: {
         auto rhs = pop_thing();
         auto lhs = pop_thing();
-        push_thing(lhs - rhs);
+        push_thing(lhs->sub(*rhs));
     } break;
     case instruction_t::Mul: {
         auto rhs = pop_thing();
         auto lhs = pop_thing();
-        push_thing(lhs * rhs);
+        push_thing(lhs->mul(*rhs));
     } break;
     case instruction_t::Div: {
         auto rhs = pop_thing();
         auto lhs = pop_thing();
-        push_thing(lhs / rhs);
+        push_thing(lhs->div(*rhs));
     } break;
     case instruction_t::Mod: {
         auto rhs = pop_thing();
         auto lhs = pop_thing();
-        push_thing(lhs % rhs);
+        push_thing(lhs->mod(*rhs));
+    } break;
+    case instruction_t::Equals: {
+        auto rhs = pop_thing();
+        auto lhs = pop_thing();
+        push_thing(lhs->equals(*rhs));
+    } break;
+    case instruction_t::NotEquals: {
+        auto rhs = pop_thing();
+        auto lhs = pop_thing();
+        push_thing(lhs->not_equals(*rhs));
+    } break;
+    case instruction_t::LessThan: {
+        auto rhs = pop_thing();
+        auto lhs = pop_thing();
+        push_thing(lhs->less_than(*rhs));
+    } break;
+    case instruction_t::GreaterThan: {
+        auto rhs = pop_thing();
+        auto lhs = pop_thing();
+        push_thing(lhs->greater_than(*rhs));
+    } break;
+    case instruction_t::LessEqual: {
+        auto rhs = pop_thing();
+        auto lhs = pop_thing();
+        push_thing(lhs->less_equals(*rhs));
+    } break;
+    case instruction_t::GreaterEqual: {
+        auto rhs = pop_thing();
+        auto lhs = pop_thing();
+        push_thing(lhs->greater_equals(*rhs));
+    } break;
+    case instruction_t::Pointerof: {
+        auto thing = pop_thing();
+        auto ptr =
+            push_thing({ (struct thing_type){ thing_type::Ptr, m_context->thing_type_store().at(thing->type().id) },
+                m_context->thing_alloc() });
+        ptr->get<void*>() = thing->raw();
+    } break;
+    case instruction_t::Sizeof: {
+        auto thing = pop_thing();
+        auto size  = push_thing({ (struct thing_type){ thing_type::U64 }, m_context->thing_alloc() });
+        switch (thing->type().type) {
+        case thing_type::S8:
+        case thing_type::S16:
+        case thing_type::S32:
+        case thing_type::S64:
+        case thing_type::U8:
+        case thing_type::U16:
+        case thing_type::U32:
+        case thing_type::U64:
+            size->get<thing_type::u64>() = static_cast<thing_type::u64>(thing_type::primitive_size(thing->type().type));
+            break;
+        case thing_type::Ptr: size->get<thing_type::u64>() = static_cast<thing_type::u64>(sizeof(void*)); break;
+        case thing_type::Array:
+            /* TODO: Return actual memory size of the array
+             * By the memory size I mean the length times sizeof single element.
+             */
+            size->get<thing_type::u64>() = thing->length();
+            break;
+        default: throw std::runtime_error("unreachable");
+        }
+    } break;
+    case instruction_t::Lengthof: {
+        auto thing  = pop_thing();
+        auto length = push_thing({ (struct thing_type){ thing_type::U64 }, m_context->thing_alloc() });
+        length->get<thing_type::u64>() = thing->length();
     } break;
     case instruction_t::Load: {
         variable_t variable = static_cast<std::uint16_t>(frame.mod->byte(frame.position)) |
                               (static_cast<std::uint16_t>(frame.mod->byte(frame.position + 1)) << 8);
+        frame.position     += 2;
         push_thing(load_thing(variable));
     } break;
     case instruction_t::Store: {
         variable_t variable = static_cast<std::uint16_t>(frame.mod->byte(frame.position)) |
                               (static_cast<std::uint16_t>(frame.mod->byte(frame.position + 1)) << 8);
+        frame.position     += 2;
         store_thing(variable, std::move(pop_thing()));
     } break;
     case instruction_t::Call: {
-        function_handle funcId = static_cast<std::uint16_t>(frame.mod->byte(frame.position)) |
-                                 (static_cast<std::uint16_t>(frame.mod->byte(frame.position + 1)) << 8);
-        frame.position        += 2;
-
-        const function_p& function = frame.mod->function_at(funcId);
-        switch (function->type()) {
-        case function_t::Normal: push_frame(function); break;
-        case function_t::Native: function->native()(*this); break;
-        case function_t::Import: {
-            const mod_p& impMod = m_context->m_modules.at(function->imported_module());
-            push_frame(impMod->function_at(function->imported_function()));
-        } break;
-        }
+        function_id funcId = static_cast<std::uint16_t>(frame.mod->byte(frame.position)) |
+                             (static_cast<std::uint16_t>(frame.mod->byte(frame.position + 1)) << 8);
+        frame.position    += 2;
+        push_frame(frame.mod, *frame.mod->function_at(funcId));
+    } break;
+    case instruction_t::Jump: {
+        std::int8_t offset = static_cast<std::int8_t>(frame.mod->byte(frame.position++));
+        frame.position    += offset;
+    } break;
+    case instruction_t::JumpNotZero: {
+        byte offset = frame.mod->byte(frame.position++);
+        auto cond   = pop_thing();
+        if (cond->integer() != 0) frame.position += (std::int8_t)offset;
     } break;
     case instruction_t::Return: {
         pop_frame();
         if (m_frames.empty()) m_flags = m_flags | executor_flags::Done;
     } break;
-    case instruction_t::ReturnValue: {
-        auto value = pop_thing();
-        pop_frame();
-        push_thing(std::move(value));
-    } break;
     case instruction_t::PushConstant: throw std::runtime_error("unimplemented");
     default: throw std::runtime_error("unknown instruction");
     }

furvm/src/function.cpp

@@ -1,15 +1,29 @@
 #include "furvm/function.hpp"
 
+#include "furvm/furvm.hpp"
+
+#include <utility>
+
 namespace furvm {
 
-function::function(funkcja, function_handle id, std::size_t position, const mod_p& mod)
-  : m_id(id), m_type(function_t::Normal), m_module(mod), m_value(position) {}
+function::function(const mod_h& mod, const function_h& function)
+  : m_type(function_t::Import), m_value(import_function{ mod.id(), function.id() }) {}
 
-function::function(funkcja, function_handle id, const native_function& native, const mod_p& mod)
-  : m_id(id), m_type(function_t::Native), m_module(mod), m_value(native) {}
+function::~function() {
+    switch (m_type) {
+    case function_t::Normal:
+    default: break;
+    case function_t::Native: {
+        m_value.native.~native_function();
+    } break;
+    case function_t::Import: {
+        m_value.imp.~import_function();
+    } break;
+    }
+}
 
 function::function(function&& other) noexcept
-  : m_id(other.m_id), m_type(other.m_type), m_module(std::move(other.m_module)) {
+  : m_type(other.m_type), m_signature(std::move(other.m_signature)) {
     switch (m_type) {
     case function_t::Normal: {
         m_value.position = other.m_value.position;
@@ -17,6 +31,10 @@ function::function(function&& other) noexcept
     case function_t::Native: {
         new (&m_value.native) native_function(std::move(other.m_value.native));
     } break;
+    case function_t::Import: {
+        new (&m_value.imp) import_function(std::move(other.m_value.imp));
+    } break;
+    default: break;
     }
     other.m_value.position = 0;
 }
@@ -24,9 +42,8 @@ function::function(function&& other) noexcept
 function& function::operator=(function&& other) noexcept {
     if (this == &other) return *this;
 
-    m_id     = other.m_id;
-    m_type   = other.m_type;
-    m_module = std::move(other.m_module);
+    m_type      = other.m_type;
+    m_signature = other.m_signature;
     switch (m_type) {
     case function_t::Normal: {
         m_value.position = other.m_value.position;
@@ -34,10 +51,59 @@ function& function::operator=(function&& other) noexcept {
     case function_t::Native: {
         new (&m_value.native) native_function(std::move(other.m_value.native));
     } break;
+    case function_t::Import: {
+        new (&m_value.imp) import_function(std::move(other.m_value.imp));
+    } break;
+    default: break;
     }
     other.m_value.position = 0;
 
     return *this;
 }
 
+function::function(const function& other)
+  : m_type(other.m_type), m_signature(other.m_signature) {
+    switch (m_type) {
+    case function_t::Normal: {
+        m_value.position = other.m_value.position;
+    } break;
+    case function_t::Native: {
+        new (&m_value.native) native_function(other.m_value.native);
+    } break;
+    case function_t::Import: {
+        new (&m_value.imp) import_function(other.m_value.imp);
+    } break;
+    default: break;
+    }
+}
+
+function& function::operator=(const function& other) {
+    if (this == &other) return *this;
+
+    m_type      = other.m_type;
+    m_signature = other.m_signature;
+    switch (m_type) {
+    case function_t::Normal: {
+        m_value.position = other.m_value.position;
+    } break;
+    case function_t::Native: {
+        new (&m_value.native) native_function(other.m_value.native);
+    } break;
+    case function_t::Import: {
+        new (&m_value.imp) import_function(other.m_value.imp);
+    } break;
+    default: break;
+    }
+
+    return *this;
+}
+
+namespace detail {
+
+std::size_t function_sig_hash::operator()(const function_sig& signature) const {
+    return furlang::utility::vector_hash<mod_type_h, detail::handle_hash<mod_type_h>>{}(signature.params);
+}
+
+} // namespace detail
+
 } // namespace furvm

furvm/src/main.cpp

@@ -1,45 +1,90 @@
 #ifndef LIBFURVM
 
-#include "furvm/context.hpp"
-#include "furvm/executor.hpp"
-#include "furvm/function.hpp"
-#include "furvm/instruction.hpp"
-#include "furvm/serializer.hpp"
-#include "furvm/thing.hpp"
+#include "furvm/detail/serialization.hpp"
+#include "furvm/furvm.hpp"
 
 #include <array>
 #include <cstddef>
 #include <fstream>
 #include <iostream>
 #include <memory>
+#include <sstream>
 
-static constexpr std::array<furvm::byte, 8> s_bytecode = {
-    furvm::byte(furvm::instruction_t::PushB2I),
-    67,
-    furvm::byte(furvm::instruction_t::Clone),
-    furvm::byte(furvm::instruction_t::Add),
-    furvm::byte(furvm::instruction_t::Return),
-};
+static void print_thing(const furvm::thing<furvm::thing_allocator>& thing) {
+    using namespace furvm;
 
-int main(void) {
+    switch (thing.true_type().type) {
+    case thing_type::S8: std::cout << thing.cast_to<thing_type::s16>(); break;
+    case thing_type::S16: std::cout << thing.get<thing_type::s16>(); break;
+    case thing_type::S32: std::cout << thing.get<thing_type::s32>(); break;
+    case thing_type::S64: std::cout << thing.get<thing_type::s64>(); break;
+    case thing_type::U8: std::cout << thing.get<thing_type::u8>(); break;
+    case thing_type::U16: std::cout << thing.get<thing_type::u16>(); break;
+    case thing_type::U32: std::cout << thing.get<thing_type::u32>(); break;
+    case thing_type::U64: std::cout << thing.get<thing_type::u64>(); break;
+    case thing_type::Array:
+        std::cout << "{ ";
+        for (thing_type::u64 i = 0; i < thing.length(); ++i) {
+            if (i > 0) std::cout << ", ";
+            print_thing(thing.at(i));
+        }
+        std::cout << " }";
+        break;
+    default: std::cerr << "{Type not recognized}";
+    }
+}
+
+int main(int argc, char** argv) {
     auto context = std::make_shared<furvm::context>();
 
-    auto mainModule = context->emplace(s_bytecode.begin(), s_bytecode.end());
+#if 1 // NOLINT
+    if (argc != 2) {
+        std::cerr << "Usage: " << argv[0] << " <mod.fmod>\n";
+        return 1;
+    }
 
-    auto mainFunction = furvm::function::create(mainModule, 0);
+    std::ifstream file(argv[1]);
+    if (!file.is_open()) {
+        std::cerr << "Failed to open " << argv[1] << '\n';
+        return 1;
+    }
 
-    std::ofstream file("./test.furm", std::ios::binary);
-    furvm::serializer::serialize_module(file, mainModule);
+    furvm::mod_h mod      = context->emplace("main", std::move(furvm::mod::load(file)));
+    auto         mainFunc = mod->function_at("main", furvm::function_sig{});
+#else
+    static const furvm::byte s_bytecode[] = {
+        static_cast<furvm::byte>(furvm::instruction_t::Array),
+        1,
+        0,
+        0,
+        0,
+        static_cast<furvm::byte>(furvm::instruction_t::Reference),
+        static_cast<furvm::byte>(furvm::instruction_t::Lengthof),
+        static_cast<furvm::byte>(furvm::instruction_t::Call),
+        1,
+        0,
+        static_cast<furvm::byte>(furvm::instruction_t::Drop),
+        static_cast<furvm::byte>(furvm::instruction_t::Return),
+    };
 
-    auto executor = furvm::executor::create(context);
-    executor->push_frame(mainFunction);
+    auto mod       = context->emplace("main", s_bytecode, s_bytecode + sizeof(s_bytecode));
+    auto charType  = mod->emplace_type(furvm::mod_type::S8);
+    auto arrayType = mod->emplace_type(charType.id(), 10);
+    auto u64Type   = mod->emplace_type(furvm::mod_type::U64);
+    auto mainFunc  = mod->emplace_function("main", furvm::function_sig{}, 0);
+    mod->emplace_function(furvm::function_sig{ { u64Type }, u64Type }, "print").dispatch();
+#endif
+    mod->set_native_function("println", [](furvm::executor& executor) {
+        auto arg = executor.load_thing(0);
+        print_thing(*arg);
+        std::cout << '\n';
+    });
 
-    static constexpr std::size_t FPC = 3; // Frames per collection
+    furvm::executor_h executor = context->emplace_executor(context);
+    executor->push_frame(mod, *mainFunc);
 
-    std::size_t count = 0;
     while ((executor->flags() & furvm::executor_flags::Done) != furvm::executor_flags::Done) {
         executor->step();
-        if ((++count % FPC) == 0) context->collect();
     }
 
     return 0;

furvm/src/module.cpp

@@ -1,3 +1,203 @@
 #include "furvm/module.hpp"
 
-namespace furvm {}
+#include "furvm/detail/serialization.hpp"
+#include "furvm/function.hpp"
+#include "furvm/fwd.hpp"
+
+#include <cstdint>
+#include <cstring>
+#include <ios>
+#include <stdexcept>
+#include <utility>
+
+namespace furvm {
+
+std::ostream& mod::serialize(std::ostream& os) const {
+    os.write(MAGIC, sizeof(MAGIC));
+    detail::serialize(os, std::uint32_t(0)); // version
+
+    mod_type_id typeCount = mod_type_id(m_types.cend() - m_types.cbegin());
+    detail::serialize(os, typeCount);
+    for (mod_type_id id = 0; id < typeCount; ++id) {
+        if (!m_types.contains(id)) {
+            detail::serialize(os, std::uint8_t(0xFF)); // null type
+            continue;
+        }
+
+        auto type = *m_types.at(id);
+        detail::serialize(os, static_cast<std::uint8_t>(type.type));
+        switch (type.type) {
+        case mod_type::S8:
+        case mod_type::S16:
+        case mod_type::S32:
+        case mod_type::S64:
+        case mod_type::U8:
+        case mod_type::U16:
+        case mod_type::U32:
+        case mod_type::U64: break;
+        case mod_type::Ptr:
+        case mod_type::Ref: detail::serialize(os, type.value.typeRef); break;
+        case mod_type::Array: {
+            detail::serialize(os, type.value.array.typeId);
+            detail::serialize(os, type.value.array.size);
+        } break;
+        case mod_type::Import: {
+            detail::serialize(os, type.value.imprt.modId);
+            detail::serialize(os, type.value.imprt.typeId);
+        } break;
+        case mod_type::Count: throw std::runtime_error("unreachable");
+        }
+    }
+
+    function_id funcCount = m_functions.cend() - m_functions.cbegin();
+    detail::serialize(os, funcCount);
+    for (function_id id = 0; id < funcCount; ++id) {
+        if (!m_functions.contains(id)) {
+            detail::serialize(os, "");
+            detail::serialize(os, 0);
+            detail::serialize(os, std::uint8_t(0xFF)); // null function
+            continue;
+        }
+
+        // Function name
+        function_h func = m_functions.at(id);
+        if (auto it = m_functionMap.find(func.id()); it != m_functionMap.end()) {
+            detail::serialize(os, it->second.first);
+        } else {
+            detail::serialize(os, "");
+        }
+
+        // Function signature
+        detail::serialize(os, static_cast<std::uint32_t>(func->signature().params.size()));
+        for (std::uint32_t i = 0; i < func->signature().params.size(); ++i)
+            detail::serialize(os, func->signature().params[i].id());
+
+        // Function body/value
+        detail::serialize(os, std::uint8_t(func->type()));
+        switch (func->type()) {
+        case function_t::Normal: {
+            detail::serialize(os, func->position());
+        } break;
+        case function_t::Native: {
+            detail::serialize(os, func->native());
+        } break;
+        case function_t::Import: {
+            detail::serialize(os, func->imp().mod);
+            detail::serialize(os, func->imp().function);
+        } break;
+        }
+    }
+
+    detail::serialize(os, std::uint64_t(m_bytecode.size()));
+    return os.write(reinterpret_cast<const char*>(m_bytecode.data()), static_cast<std::streamsize>(m_bytecode.size()));
+}
+
+mod mod::load(std::istream& is) {
+    std::uint32_t magic = 0;
+    detail::load(is, magic);
+    std::uint32_t version = 0;
+    detail::load(is, version);
+    if (std::memcmp(&magic, MAGIC, sizeof(MAGIC)) != 0) throw std::runtime_error("invalid magic");
+    if (version != 0) throw std::runtime_error("unsupported version");
+
+    mod mod;
+
+    mod_type_id typeCount = 0;
+    detail::load(is, typeCount);
+    for (mod_type_id id = 0; id < typeCount; ++id) {
+        std::uint8_t type = 0;
+        detail::load(is, type);
+        if (type == 0xFF) continue;
+
+        switch ((enum mod_type::type)type) {
+        case mod_type::S8:
+        case mod_type::S16:
+        case mod_type::S32:
+        case mod_type::S64:
+        case mod_type::U8:
+        case mod_type::U16:
+        case mod_type::U32:
+        case mod_type::U64: {
+            mod_type theType = { (enum mod_type::type)type };
+            mod.emplace_type(id, theType).dispatch();
+        } break;
+        case mod_type::Ptr: {
+            mod_type_id typeId = 0;
+            detail::load(is, typeId);
+            mod.emplace_type(id, typeId).dispatch();
+        } break;
+        case mod_type::Array: {
+            mod_type_id typeId = 0;
+            detail::load(is, typeId);
+            std::size_t size = 0;
+            detail::load(is, size);
+            mod.emplace_type(id, typeId, size).dispatch();
+        } break;
+        case mod_type::Import: {
+            std::string modName;
+            detail::load(is, modName);
+            mod_type_id typeId = 0;
+            detail::load(is, typeId);
+            mod.emplace_type(id, std::move(modName), typeId).dispatch();
+        } break;
+        default: throw std::runtime_error("unknown type type");
+        }
+    }
+
+    function_id functionCount = 0;
+    detail::load(is, functionCount);
+    for (function_id id = 0; id < functionCount; ++id) {
+        std::string name;
+        detail::load(is, name);
+
+        function_sig  signature;
+        std::uint32_t paramCount = 0;
+        detail::load(is, paramCount);
+        signature.params.reserve(paramCount);
+        while (signature.params.size() < paramCount) {
+            thing_id param{ 0 };
+            detail::load(is, param);
+            signature.params.emplace_back(mod.type_at(param));
+        }
+
+        std::uint8_t type = 0;
+        detail::load(is, type);
+        if (type == 0xFF) continue;
+
+        switch ((function_t)type) {
+        case function_t::Normal: {
+            decltype(std::declval<function>().position()) offset = 0;
+            detail::load(is, offset);
+            if (name.empty())
+                mod.emplace_function(id, std::move(signature), offset).dispatch();
+            else
+                mod.emplace_function(std::move(name), id, std::move(signature), offset).dispatch();
+        } break;
+        case function_t::Native: {
+            std::string native;
+            detail::load(is, native);
+            if (name.empty())
+                mod.emplace_function(id, std::move(signature), std::move(native)).dispatch();
+            else
+                mod.emplace_function(std::move(name), id, std::move(signature), std::move(native)).dispatch();
+        } break;
+        case function_t::Import: {
+            std::string modName;
+            detail::load(is, modName);
+            function_id function = 0;
+            detail::load(is, function);
+            mod.emplace_function(id, std::move(modName), function).dispatch();
+        } break;
+        default: throw std::runtime_error("unknown function type");
+        }
+    }
+
+    std::uint64_t bytecodeLength = 0;
+    detail::load(is, bytecodeLength);
+    mod.bytecode().resize(bytecodeLength);
+    is.read(reinterpret_cast<char*>(mod.bytecode().data()), static_cast<std::streamsize>(bytecodeLength));
+
+    return mod;
+}
+
+} // namespace furvm

furvm/src/serializer.cpp

@@ -1,101 +0,0 @@
-#include "furvm/serializer.hpp"
-
-#include "furvm/function.hpp" // IWYU pragma: keep
-
-#include <array>
-#include <cstring>
-#include <istream>
-#include <optional>
-#include <ostream>
-#include <stdexcept>
-
-namespace furvm {
-
-template <typename T>
-static inline void write_raw(std::ostream& os, const T& value) {
-    os.write(reinterpret_cast<const char*>(&value), sizeof(T));
-}
-
-template <typename T>
-static inline void read_raw(std::istream& is, T& value) {
-    is.read(reinterpret_cast<char*>(&value), sizeof(T));
-}
-
-static inline void write_u64(std::ostream& os, std::uint64_t value) {
-    os.put(static_cast<char>((value >> 0ULL) & 0xFF));
-    os.put(static_cast<char>((value >> 8ULL) & 0xFF));
-    os.put(static_cast<char>((value >> 16ULL) & 0xFF));
-    os.put(static_cast<char>((value >> 24ULL) & 0xFF));
-    os.put(static_cast<char>((value >> 32ULL) & 0xFF));
-    os.put(static_cast<char>((value >> 40ULL) & 0xFF));
-    os.put(static_cast<char>((value >> 48ULL) & 0xFF));
-    os.put(static_cast<char>((value >> 56ULL) & 0xFF));
-}
-
-static inline void read_u64(std::istream& is, std::uint64_t& value) {
-    value = (static_cast<std::uint64_t>(is.get()) << 0) | (static_cast<std::uint64_t>(is.get()) << 8) |
-            (static_cast<std::uint64_t>(is.get()) << 16) | (static_cast<std::uint64_t>(is.get()) << 24) |
-            (static_cast<std::uint64_t>(is.get()) << 32) | (static_cast<std::uint64_t>(is.get()) << 40) |
-            (static_cast<std::uint64_t>(is.get()) << 48) | (static_cast<std::uint64_t>(is.get()) << 56);
-}
-
-static inline void write_u32(std::ostream& os, std::uint32_t value) {
-    os.put(static_cast<char>((value >> 0ULL) & 0xFF));
-    os.put(static_cast<char>((value >> 8ULL) & 0xFF));
-    os.put(static_cast<char>((value >> 16ULL) & 0xFF));
-    os.put(static_cast<char>((value >> 24ULL) & 0xFF));
-}
-
-static inline void read_u32(std::istream& is, std::uint32_t& value) {
-    value = static_cast<std::uint32_t>(is.get() << 0) | static_cast<std::uint32_t>(is.get() << 8) |
-            static_cast<std::uint32_t>(is.get() << 16) | static_cast<std::uint32_t>(is.get() << 24);
-}
-
-static inline void write_u16(std::ostream& os, std::uint16_t value) {
-    os.put(static_cast<char>((value >> 0ULL) & 0xFF));
-    os.put(static_cast<char>((value >> 8ULL) & 0xFF));
-}
-
-static inline void read_u16(std::istream& is, std::uint16_t& value) {
-    value = static_cast<std::uint16_t>(is.get() << 0) | static_cast<std::uint16_t>(is.get() << 8);
-}
-
-static inline void write_u8(std::ostream& os, std::uint8_t value) {
-    os.put(static_cast<char>((value >> 0ULL) & 0xFF));
-}
-
-static inline void read_u8(std::istream& is, std::uint8_t& value) {
-    value = static_cast<std::uint8_t>(is.get() << 0);
-}
-
-bool serializer::serialize_module(std::ostream& os, const mod_p& mod) {
-    os.write(reinterpret_cast<const char*>(MODULE_MAGIC), sizeof(MODULE_MAGIC));
-    write_u32(os, VERSION);
-
-    write_u32(os, mod->m_functions.size());
-    for (const auto& func : mod->m_functions) {
-        write_u16(os, func->id());
-        write_u8(os, static_cast<std::uint8_t>(func->type()));
-        switch (func->type()) {
-        case function_t::Normal: {
-            write_u64(os, func->position());
-        } break;
-        case function_t::Native: {
-            // TODO: Replace with a reference to the function's name from constant pool
-            throw std::runtime_error("cannot serialize native functions yet");
-        } break;
-        case function_t::Import: {
-            // TODO: Replace with a reference to the module's and function's name from constant pool
-            throw std::runtime_error("cannot serialize import functions yet");
-        } break;
-        }
-    }
-
-    write_u64(os, mod->m_bytecode.size());
-    os.write(reinterpret_cast<const char*>(mod->m_bytecode.data()),
-        static_cast<std::streamsize>(mod->m_bytecode.size()));
-
-    return false;
-}
-
-} // namespace furvm

furvm/src/thing.cpp

@@ -1,177 +0,0 @@
-// NOLINTBEGIN(cppcoreguidelines-no-malloc)
-
-#include "furvm/thing.hpp"
-
-#include "furvm/context.hpp" // IWYU pragma: keep
-
-#include <cstdlib>
-#include <cstring>
-#include <stdexcept>
-
-namespace furvm {
-
-std::size_t thing_type_size(thing_t type) {
-    switch (type) {
-    case thing_t::Int32: return 4;
-    }
-    return 0;
-}
-
-thing::thing(rzecz, thing_handle id, thing_t type, const context_p& context)
-  : m_id(id), m_type(type), m_context(context) {
-    std::size_t size = thing_type_size(type);
-    std::byte*  data = nullptr;
-    if (!m_context->m_deadThingData.empty()) {
-        thing_t itType{};
-        for (auto it = m_context->m_deadThingData.rbegin(); it != m_context->m_deadThingData.rend(); ++it) {
-            std::memcpy(&itType, static_cast<std::byte*>(*it) - sizeof(itType), sizeof(itType));
-            if (size == thing_type_size(itType)) {
-                data = static_cast<std::byte*>(*it);
-                m_context->m_deadThingData.erase(std::next(it).base());
-                break;
-            }
-        }
-    }
-    if (data == nullptr) data = m_context->m_thingArena.allocate<std::byte>(sizeof(type) + size);
-
-    if (data == nullptr) throw std::runtime_error("failed to allocate data for new thing");
-    std::memcpy(data, &type, sizeof(type));
-    m_data = data + sizeof(type);
-
-    switch (m_type) {
-    // Primitives are zero-initialized.
-    default:
-    case thing_t::Int32: std::memset(m_data, 0, size);
-    }
-}
-
-thing::~thing() {
-    switch (m_type) {
-    // Primitives are not destructed.
-    default:
-    case thing_t::Int32: break;
-    }
-
-    m_context->m_deadThingData.push_back(m_data);
-}
-
-thing::thing(thing&& other) noexcept
-  : m_id(other.m_id),
-    m_type(other.m_type),
-    m_context(std::move(other.m_context)),
-    m_refCount(other.m_refCount),
-    m_data(other.m_data) {
-    other.m_id       = {};
-    other.m_type     = {};
-    other.m_refCount = {};
-    other.m_data     = nullptr;
-}
-
-thing& thing::operator=(thing&& other) noexcept {
-    if (this == &other) return *this;
-    m_id       = other.m_id;
-    m_type     = other.m_type;
-    m_context  = std::move(other.m_context);
-    m_refCount = other.m_refCount;
-    m_data     = other.m_data;
-
-    other.m_id       = {};
-    other.m_type     = {};
-    other.m_refCount = {};
-    other.m_data     = nullptr;
-    return *this;
-}
-
-static constexpr std::uint16_t thing_type_pair(thing_t lhs, thing_t rhs) {
-    return (static_cast<std::uint16_t>(lhs) << 8) | static_cast<std::uint16_t>(rhs);
-}
-
-thing_p operator+(const thing_p& lhs, const thing_p& rhs) {
-    switch (thing_type_pair(lhs->m_type, rhs->m_type)) {
-    case thing_type_pair(thing_t::Int32, thing_t::Int32): {
-        auto res     = thing::create(lhs->m_context, thing_t::Int32);
-        res->int32() = lhs->int32() + rhs->int32();
-        return res;
-    }
-    default: throw std::runtime_error("unexpected operator");
-    }
-}
-
-thing_p operator-(const thing_p& lhs, const thing_p& rhs) {
-    switch (thing_type_pair(lhs->m_type, rhs->m_type)) {
-    case thing_type_pair(thing_t::Int32, thing_t::Int32): {
-        auto res     = thing::create(lhs->m_context, thing_t::Int32);
-        res->int32() = lhs->int32() - rhs->int32();
-        return res;
-    }
-    default: throw std::runtime_error("unexpected operator");
-    }
-}
-
-thing_p operator*(const thing_p& lhs, const thing_p& rhs) {
-    switch (thing_type_pair(lhs->m_type, rhs->m_type)) {
-    case thing_type_pair(thing_t::Int32, thing_t::Int32): {
-        auto res     = thing::create(lhs->m_context, thing_t::Int32);
-        res->int32() = lhs->int32() * rhs->int32();
-        return res;
-    }
-    default: throw std::runtime_error("unexpected operator");
-    }
-}
-
-thing_p operator/(const thing_p& lhs, const thing_p& rhs) {
-    switch (thing_type_pair(lhs->m_type, rhs->m_type)) {
-    case thing_type_pair(thing_t::Int32, thing_t::Int32): {
-        auto res     = thing::create(lhs->m_context, thing_t::Int32);
-        res->int32() = lhs->int32() / rhs->int32();
-        return res;
-    }
-    default: throw std::runtime_error("unexpected operator");
-    }
-}
-
-thing_p operator%(const thing_p& lhs, const thing_p& rhs) {
-    switch (thing_type_pair(lhs->m_type, rhs->m_type)) {
-    case thing_type_pair(thing_t::Int32, thing_t::Int32): {
-        auto res     = thing::create(lhs->m_context, thing_t::Int32);
-        res->int32() = lhs->int32() % rhs->int32();
-        return res;
-    }
-    default: throw std::runtime_error("unexpected operator");
-    }
-}
-
-thing_p thing::clone(const thing_p& thing) {
-    thing_handle id = thing->m_context->m_things.size();
-    if (!thing->m_context->m_deadThings.empty()) {
-        id = thing->m_context->m_deadThings.front();
-        thing->m_context->m_deadThings.pop();
-        id += 1 << GENERATION_SIZE;
-    }
-    thing_handle idx = id & ((1ULL << ((sizeof(id) * 8) - GENERATION_SIZE)) - 1);
-
-    auto th = std::make_shared<class thing>(rzecz{}, id, thing->m_type, thing->m_context);
-    switch (thing->m_type) {
-    // Primitives
-    default: {
-        memcpy(th->m_data, thing->m_data, thing_type_size(thing->m_type));
-    }
-    }
-
-    thing->m_context->m_things.emplace(thing->m_context->m_things.begin() + idx, th);
-    return std::move(th);
-}
-
-std::int32_t& thing::int32() {
-    if (m_type != thing_t::Int32) throw bad_thing_access();
-    return *static_cast<std::int32_t*>(m_data);
-}
-
-const std::int32_t& thing::int32() const {
-    if (m_type != thing_t::Int32) throw bad_thing_access();
-    return *static_cast<std::int32_t*>(m_data);
-}
-
-} // namespace furvm
-
-// NOLINTEND(cppcoreguidelines-no-malloc)

furvm/test/test.cpp

@@ -1,3 +1,28 @@
+#include "furlang/arena.hpp"
+#include "furvm/furvm.hpp"
+#include "furvm/thing.hpp"
+#include "furvm/thing_allocator.hpp"
+
 #include "gtest/gtest.h" // IWYU pragma: keep
 
-namespace {}
+namespace {
+
+// TODO: Basic program tests (e.g. for loops)
+
+TEST(Things, Ops) {
+    furlang::arena                    arena;
+    furvm::thing_allocator<std::byte> alloc{ arena };
+
+    furvm::thing lhs{ furvm::thing_type{ furvm::thing_type::U32 }, alloc };
+    lhs.get<furvm::thing_type::u32>() = 6;
+    furvm::thing rhs{ furvm::thing_type{ furvm::thing_type::U32 }, alloc };
+    rhs.get<furvm::thing_type::u32>() = 7;
+
+    auto res = lhs.add(rhs);
+    ASSERT_EQ(res.type().type, furvm::thing_type::U32);
+    EXPECT_EQ(lhs.get<furvm::thing_type::u32>(), 6);
+    EXPECT_EQ(rhs.get<furvm::thing_type::u32>(), 7);
+    EXPECT_EQ(res.get<furvm::thing_type::u32>(), 6 + 7);
+}
+
+} // namespace