feat: implement module loading

I couldn't care less to commit all the changes separately after fight
with this stupid codebase.
Also I am closing the issue since serializing contexts meant doing
something like jars which I don't want to do right now. I'll reopen the
issue though for sure clueless.

Closes: #23

furvm/src/module.cpp

@@ -4,19 +4,25 @@
 #include "furvm/fwd.hpp"
 #include "furvm/type.hpp"
 
+#include <cstdint>
+#include <cstring>
 #include <ios>
+#include <memory>
 #include <stdexcept>
+#include <utility>
 
 namespace furvm {
 
 std::ostream& mod::serialize(std::ostream& os) const {
-    os << MAGIC;
+    os.write(MAGIC, sizeof(MAGIC));
     detail::serialize(os, std::uint32_t(0)); // version
 
-    detail::serialize(os, function_id(m_functionMap.size()));
-    for (function_id id = 0; id < m_functions.cend() - m_functions.cbegin(); ++id) {
+    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;
         }
@@ -24,12 +30,15 @@ std::ostream& mod::serialize(std::ostream& os) const {
         function_h func     = m_functions.at(id);
         bool       isPublic = m_publicFunctions.find(func->name()) != m_publicFunctions.end();
         detail::serialize(os, isPublic ? func->name() : ""); // private functions have empty names
+        detail::serialize(os, func->param_count());
         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: 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);
@@ -60,4 +69,86 @@ std::ostream& mod::serialize(std::ostream& os) const {
     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;
+
+    function_id functionCount = 0;
+    detail::load(is, functionCount);
+    for (function_id id = 0; id < functionCount; ++id) {
+        std::string name;
+        detail::load(is, name);
+        std::uint32_t paramCount = 0;
+        detail::load(is, paramCount);
+        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);
+            mod.emplace_function(id, std::move(name), paramCount, offset).dispatch();
+        } break;
+        case function_t::Native: {
+            std::string native;
+            detail::load(is, native);
+            mod.emplace_function(id, std::move(name), paramCount, 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");
+        }
+    }
+
+    type_id typeCount = 0;
+    detail::load(is, typeCount);
+    for (type_id id = 0; id < typeCount; ++id) {
+        std::uint8_t type = 0;
+        detail::load(is, type);
+        if (type == 0xFF) continue;
+
+        switch ((type_t)type) {
+        case type_t::Primitive: {
+            primitive_type primitive = 0;
+            detail::load(is, primitive);
+            mod.emplace_type(id, std::make_shared<class type>(primitive)).dispatch();
+        } break;
+        case type_t::Reference: throw std::runtime_error("reference type serialization is unimplemented");
+        case type_t::List: {
+            type_id typeId = 0;
+            detail::load(is, typeId);
+            mod.emplace_type(id, std::make_shared<class type>(mod.type_at(typeId))).dispatch();
+        } break;
+        case type_t::Import: {
+            std::string modName;
+            detail::load(is, modName);
+            type_id typeId = 0;
+            detail::load(is, typeId);
+            mod.emplace_type(id, std::make_shared<class type>(import_type{ std::move(modName), typeId })).dispatch();
+        } break;
+        default: throw std::runtime_error("unknown type 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