feat(furvm): implement constants

Closes: #13

furvm/include/furvm/constant.hpp

@@ -1,74 +1,29 @@
 #ifndef FURVM_CONSTANT_HPP
 #define FURVM_CONSTANT_HPP
 
-#include "furvm/exceptions.hpp"
 #include "furvm/fwd.hpp"
 
+#include <cstdint>
 #include <string_view>
 
 namespace furvm {
 
-enum class constant_t : std::uint8_t {
+// TODO: Array constants
-    String, /**< String constant. */
+struct constant {
+    enum type_e {
+        S32 = 0,
+        U32,
+        S64,
+        U64,
+        String,
+    } type = S32;
+    union {
+        std::int32_t     s32;
+        std::uint32_t    u32;
+        std::int64_t     s64;
+        std::uint64_t    u64;
+        std::string_view string;
     };
-
-class constant {
-public:
-    using string_type = std::string_view; /**< String constant type. */
-public:
-    /**
-     * @brief Construct a new string constant.
-     *
-     * @param string String.
-     */
-    constant(string_type string)
-      : m_type(constant_t::String), m_value(string) {}
-
-    ~constant() = default;
-
-    /**
-     * @brief Move constructor.
-     */
-    constant(constant&&) = default;
-
-    /**
-     * @brief Move constructor.
-     */
-    constant& operator=(constant&&) = default;
-
-    constant(const constant&)            = delete;
-    constant& operator=(const constant&) = delete;
-public:
-    /**
-     * @brief Returns this constant's type.
-     * @see constant_t
-     *
-     * @return The constant type.
-     */
-    constexpr constant_t type() const { return m_type; }
-
-    /**
-     * @brief Returns this constant's string value.
-     * @throws bad_constant_access if this constant's type is not constant_t::String.
-     *
-     * @return The string value.
-     */
-    constexpr string_type string() const {
-        require_type(constant_t::String);
-        return m_value.string;
-    }
-private:
-    void require_type(constant_t type) const {
-        if (m_type != type) throw bad_constant_access();
-    }
-private:
-    constant_t m_type{};
-    union value {
-        string_type string;
-
-        value(string_type sv)
-          : string(sv) {}
-    } m_value;
 };
 
 } // namespace furvm

furvm/include/furvm/module.hpp

@@ -3,6 +3,7 @@
 
 #include "furlang/utility/hash.hpp"
 #include "furlang/view.hpp"
+#include "furvm/constant.hpp"
 #include "furvm/function.hpp"
 #include "furvm/fwd.hpp"
 #include "furvm/handle.hpp"
@@ -10,8 +11,6 @@
 
 #include <functional>
 #include <istream>
-#include <limits>
-#include <optional>
 #include <ostream>
 #include <stdexcept>
 #include <string>
@@ -384,6 +383,13 @@ public:
         if (var >= m_globalVariables.size()) throw std::runtime_error("invalid slot");
         return m_globalVariables[var];
     }
+public:
+    template <typename... Args, typename = std::enable_if_t<std::is_constructible_v<constant, Args...>>>
+    void emplace_constant(Args&&... args) {
+        m_constants.emplace_back(std::forward<Args>(args)...);
+    }
+
+    const constant& constant_at(constant_index index) const { return m_constants.at(index); }
 public:
     template <typename Fwd, typename = std::enable_if_t<std::is_constructible_v<breakpoint, Fwd>>>
     void set_breakpoint(bytecode_pos pos, Fwd&& breakpoint) {
@@ -423,6 +429,8 @@ private:
 
     std::vector<thing<>> m_globalVariables;
 
+    std::vector<constant> m_constants;
+
     std::unordered_map<std::string, native_function> m_nativeFunctions;
 
     std::unordered_map<bytecode_pos, breakpoint> m_breakpoints;

furvm/src/executor.cpp

@@ -222,6 +222,25 @@ void executor::step() {
         push_thing({ (struct thing_type){ thing_type::U32 } }).get<thing_type::u32>() =
             static_cast<thing_type::u32>(instr.arg.u8);
     } break;
+    case instruction_t::PushConstant: {
+        auto constant = frame.mod->constant_at(instr.arg.u16);
+        switch (constant.type) {
+        case constant::S32:
+            push_thing({ (struct thing_type){ thing_type::S32 } }).get<thing_type::s32>() = constant.s32; // NOLINT
+            break;
+        case constant::U32:
+            push_thing({ (struct thing_type){ thing_type::U32 } }).get<thing_type::u32>() = constant.u32; // NOLINT
+            break;
+        case constant::S64:
+            push_thing({ (struct thing_type){ thing_type::S64 } }).get<thing_type::s64>() = constant.s64; // NOLINT
+            break;
+        case constant::U64:
+            push_thing({ (struct thing_type){ thing_type::U64 } }).get<thing_type::u64>() = constant.u64; // NOLINT
+            break;
+        case constant::String: throw std::runtime_error("unimplemented");
+        default: throw std::runtime_error("invalid constant");
+        }
+    } break;
     case instruction_t::Array: {
         const auto& type = *mod_to_thing_type(frame.mod, *frame.mod->type_at(instr.arg.u32));
         if (type.type != thing_type::Array || type.value.array.type == nullptr || type.value.array.type == &type)
@@ -377,7 +396,6 @@ void executor::step() {
         pop_frame();
         if (m_frames.empty()) m_flags = m_flags | executor_flags::Done;
     } break;
-    case instruction_t::PushConstant: throw std::runtime_error("unimplemented");
     default: throw std::runtime_error("unknown instruction");
     }
 }

furvm/src/instruction.cpp

@@ -22,7 +22,7 @@ const std::size_t instruction_argument::s_sizes[instruction_argument::Count] = {
     // U32
     1,
     // Constant:
-    4,
+    2,
     // Type:
     4,
     // Variable:

furvm/src/module.cpp

@@ -16,6 +16,19 @@ std::ostream& mod::serialize(std::ostream& os) const {
     os.write(MAGIC, sizeof(MAGIC));
     detail::serialize(os, std::uint32_t(0)); // version
 
+    detail::serialize(os, static_cast<constant_index>(m_constants.size()));
+    for (const auto& constant : m_constants) {
+        detail::serialize(os, constant.type);
+        switch (constant.type) {
+        case constant::S32:
+        case constant::U32: detail::serialize(os, constant.u32); break;
+        case constant::S64:
+        case constant::U64: detail::serialize(os, constant.u64); break;
+        case constant::String: throw std::runtime_error("unimplemented");
+        default: throw std::runtime_error("unreachable");
+        }
+    }
+
     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) {
@@ -104,6 +117,22 @@ mod mod::load(std::istream& is) {
 
     mod mod;
 
+    constant_index constantCount = 0;
+    detail::load(is, constantCount);
+    mod.m_constants.reserve(constantCount);
+    for (; constantCount != 0; --constantCount) {
+        constant constant{};
+        detail::load(is, reinterpret_cast<std::uint32_t&>(constant.type));
+        switch (constant.type) {
+        case constant::S32:
+        case constant::U32: detail::load(is, constant.u32); break;
+        case constant::S64:
+        case constant::U64: detail::load(is, constant.u64); break;
+        case constant::String: throw std::runtime_error("unimplemented");
+        default: throw std::runtime_error("unreachable");
+        }
+    }
+
     mod_type_id typeCount = 0;
     detail::load(is, typeCount);
     for (mod_type_id id = 0; id < typeCount; ++id) {