Quick lua c++ bindings

gistfile1.txt

extern "C" {
#include "lauxlib.h"
#include "lualib.h"
}

#include <stdio.h>
#include <windows.h>
#include <vector>


struct Base
{
    Base() :
        FieldInt(42),
        FieldFloat(43.0f)
    {

    }

    virtual ~Base()
    {

    }

    int FieldInt;
    float FieldFloat;

    int InstanceMethodGetInt() const
    {
        return FieldInt;
    }

    float InstanceMethodGetFloat() const
    {
        return FieldFloat;
    }

    const char* InstanceMethodCall() const
    {
        static const char* Value = "Base::InstanceMethodCall";
        return Value;
    }

    virtual const char* InstanceMethodCallOverloaded() const
    {
        static const char* Value = "Base::InstanceMethodCallOverloaded";
        return Value;
    }

    static const char* StaticMethodCall()
    {
        static const char* Value = "Base::StaticMethodCall";
        return Value;
    }

    virtual const char* ToString() const
    {
        static const char* Value = "Base";
        return Value;
    }
};


int Base_Constructor(lua_State* LuaState)
{
    void* Ptr = lua_newuserdata(LuaState, sizeof(Base));
    Base* Value = new(Ptr) Base();

    luaL_getmetatable(LuaState, "MetaBase");
    lua_setmetatable(LuaState, -2);

    return 1;
}


int Base_InstanceMethodGetInt(lua_State* LuaState)
{
    Base* Value = (Base*) lua_touserdata(LuaState, 1);

    lua_pushinteger(LuaState, Value->FieldInt);
    return 1;
}


int Base_InstanceMethodGetFloat(lua_State* LuaState)
{
    Base* Value = (Base*) lua_touserdata(LuaState, 1);

    lua_pushnumber(LuaState, Value->FieldFloat);
    return 1;
}


int Base_InstanceMethodCall(lua_State* LuaState)
{
    Base* Value = (Base*) lua_touserdata(LuaState, 1);

    static const char* Str = "Base_InstanceMethodCall";
    lua_pushstring(LuaState, Str);
    return 1;
}


int Base_InstanceMethodCallOverloaded(lua_State* LuaState)
{
    Base* Value = (Base*) lua_touserdata(LuaState, 1);

    static const char* Str = "Base_InstanceMethodCallOverloaded";
    lua_pushstring(LuaState, Str);
    return 1;
}


int Base_StaticMethodCall(lua_State* LuaState)
{
    static const char* Value = "Base_StaticMethodCall";
    lua_pushstring(LuaState, Value);
    return 1;
}


int Base_ToString(lua_State* LuaState)
{
    static const char* Value = "Base";
    lua_pushstring(LuaState, Value);

    return 1;
}


struct Derived : public Base
{
    Derived() : 
        Base(),
        bFieldBoolean(true)
    {
        FieldInt = 420;
        FieldFloat = 430.0f;
    }

    bool bFieldBoolean;

    bool InstanceMethodGetBool() const
    {
        return bFieldBoolean;
    }

    virtual const char* InstanceMethodCallOverloaded() const override
    {
        static const char* Value = "Derived::InstanceMethodCall";
        return Value;
    }

    virtual const char* ToString() const override
    {
        static const char* Value = "Derived";
        return Value;
    }
};


int Derived_Constructor(lua_State* LuaState)
{
    void* Ptr = lua_newuserdata(LuaState, sizeof(Derived));
    Derived* Value = new(Ptr) Derived();

    luaL_getmetatable(LuaState, "MetaDerived");
    lua_setmetatable(LuaState, -2);

    return 1;
}


int Derived_InstanceMethodCallOverloaded(lua_State* LuaState)
{
    Derived* Value = (Derived*) lua_touserdata(LuaState, 1);

    static const char* Str = "Derived_InstanceMethodCallOverloaded";
    lua_pushstring(LuaState, Str);
    return 1;
}


int Derived_InstanceMethodGetBool(lua_State* LuaState)
{
    Derived* Value = (Derived*) lua_touserdata(LuaState, 1);

    lua_pushboolean(LuaState, Value->bFieldBoolean);
    return 1;
}


int Derived_ToString(lua_State* LuaState)
{
    static const char* Value = "Derived";
    lua_pushstring(LuaState, Value);

    return 1;
}


struct FurtherDerived : public Derived
{
    FurtherDerived() :
        Derived()
    {
    }

    virtual const char* ToString() const override
    {
        static const char* Value = "FurtherDerived";
        return Value;
    }
};


int FurtherDerived_Constructor(lua_State* LuaState)
{
    void* Ptr = lua_newuserdata(LuaState, sizeof(FurtherDerived));
    FurtherDerived* Value = new(Ptr) FurtherDerived();

    luaL_getmetatable(LuaState, "MetaFurtherDerived");
    lua_setmetatable(LuaState, -2);

    return 1;
}


int FurtherDerived_ToString(lua_State* LuaState)
{
    static const char* Value = "FurtherDerived";
    lua_pushstring(LuaState, Value);

    return 1;
}


int Print(lua_State* LuaState)
{
    const int NumArgs = lua_gettop(LuaState);

    for(int Idx = 1; Idx <= NumArgs; ++Idx)
    {
        size_t Len;
        const char* Str = luaL_tolstring(LuaState, Idx, &Len);
        OutputDebugStringA(Str);
    }

    OutputDebugStringA("\n");
    return 0;
}


int main(int argc, char** argv)
{
    lua_State* LuaState = luaL_newstate();
    luaL_openlibs(LuaState);

    // Override global print.
    {
        lua_getglobal(LuaState, "_G");
        lua_pushcfunction(LuaState, &Print);
        lua_setfield(LuaState, -2, "print");
    }

    // Our global namespace table.
    {
        lua_newtable(LuaState);
        lua_setglobal(LuaState, "BT");
    }

    // Register a list of functions.
    auto RegisterFunctions = [&LuaState](const std::vector<luaL_Reg>& Functions)
    {
        for(const luaL_Reg& Func : Functions)
        {
            lua_pushcfunction(LuaState, Func.func);
            lua_setfield(LuaState, -2, Func.name);
        }
    };

    // Base type.
    {
        // Meta table.
        {
            luaL_newmetatable(LuaState, "MetaBase");

            {
                std::vector<luaL_Reg> InstaceMethods;

                InstaceMethods.push_back({ "InstanceMethodGetInt", &Base_InstanceMethodGetInt });
                InstaceMethods.push_back({ "InstanceMethodGetFloat", &Base_InstanceMethodGetFloat });
                InstaceMethods.push_back({ "InstanceMethodCall", &Base_InstanceMethodCall });
                InstaceMethods.push_back({ "InstanceMethodCallOverloaded", &Base_InstanceMethodCallOverloaded });
                InstaceMethods.push_back({ "ToString", &Base_ToString });
                InstaceMethods.push_back({ "__tostring", &Base_ToString });
                InstaceMethods.push_back({ "__call", &Base_Constructor });

                RegisterFunctions(InstaceMethods);
            }

            // Set to itself.
            lua_pushvalue(LuaState, -1);
            lua_setfield(LuaState, -2, "__index");

            lua_pop(LuaState, 1);
        }

        // Base table.
        {
            lua_getglobal(LuaState, "BT");
            lua_newtable(LuaState);

            {
                std::vector<luaL_Reg> StaticMethods;

                StaticMethods.push_back({ "StaticMethodCall", &Base_StaticMethodCall });

                RegisterFunctions(StaticMethods);
            }

            // Set meta table for this table.
            luaL_getmetatable(LuaState, "MetaBase");
            lua_setmetatable(LuaState, -2);

            // Store this table in global namespace.
            lua_setfield(LuaState, -2, "Base");
            lua_pop(LuaState, 1);
        }
    }

    // Derived type.
    {
        // Meta table.
        {
            luaL_newmetatable(LuaState, "MetaDerived");

            {
                std::vector<luaL_Reg> InstaceMethods;

                InstaceMethods.push_back({ "InstanceMethodGetBool", &Derived_InstanceMethodGetBool });
                InstaceMethods.push_back({ "InstanceMethodCallOverloaded", &Derived_InstanceMethodCallOverloaded });
                InstaceMethods.push_back({ "ToString", &Derived_ToString });
                InstaceMethods.push_back({ "__tostring", &Derived_ToString });
                InstaceMethods.push_back({ "__call", &Derived_Constructor });

                RegisterFunctions(InstaceMethods);
            }

            // Set to itself.
            lua_pushvalue(LuaState, -1);
            //luaL_getmetatable(LuaState, "MetaBase");
            lua_setfield(LuaState, -2, "__index");

            luaL_getmetatable(LuaState, "MetaBase");
            lua_setmetatable(LuaState, -2);

            lua_pop(LuaState, 1);
        }

        // Derived table.
        {
            lua_getglobal(LuaState, "BT");
            lua_newtable(LuaState);

            {
                std::vector<luaL_Reg> StaticMethods;


                RegisterFunctions(StaticMethods);
            }

            // Set meta table for this table.
            luaL_getmetatable(LuaState, "MetaDerived");
            lua_setmetatable(LuaState, -2);

            // Store this table in global namespace.
            lua_setfield(LuaState, -2, "Derived");
            lua_pop(LuaState, 1);
        }
    }

    // FurtherDerived type.
    {
        // Meta table.
        {
            luaL_newmetatable(LuaState, "MetaFurtherDerived");

            {
                std::vector<luaL_Reg> InstaceMethods;

                InstaceMethods.push_back({ "ToString", &FurtherDerived_ToString });
                InstaceMethods.push_back({ "__tostring", &FurtherDerived_ToString });
                InstaceMethods.push_back({ "__call", &FurtherDerived_Constructor });

                RegisterFunctions(InstaceMethods);
            }

            // Set to itself.
            lua_pushvalue(LuaState, -1);
            lua_setfield(LuaState, -2, "__index");

            luaL_getmetatable(LuaState, "MetaDerived");
            lua_setmetatable(LuaState, -2);

            lua_pop(LuaState, 1);
        }

        // FurtherDerived table.
        {
            lua_getglobal(LuaState, "BT");
            lua_newtable(LuaState);

            {
                std::vector<luaL_Reg> StaticMethods;


                RegisterFunctions(StaticMethods);
            }

            // Set meta table for this table.
            luaL_getmetatable(LuaState, "MetaFurtherDerived");
            lua_setmetatable(LuaState, -2);

            // Store this table in global namespace.
            lua_setfield(LuaState, -2, "FurtherDerived");
            lua_pop(LuaState, 1);
        }
    }

    const char* Code = ""
        "local a = BT.Base()\n"
        "print(a)\n"

        "local r = BT.Base.StaticMethodCall()\n"
        "print(\"BT.Base.StaticMethodCall() -> \" .. r)\n"

        "local r = a:InstanceMethodGetInt()\n"
        "print(\"a:InstanceMethodGetInt() -> \" .. r)\n"

        "local r = a:InstanceMethodGetFloat()\n"
        "print(\"a:InstanceMethodGetFloat() -> \" .. r)\n"

        "local r = a:InstanceMethodCall()\n"
        "print(\"a:InstanceMethodCall() -> \" .. r)\n"

        "local r = a:InstanceMethodCallOverloaded()\n"
        "print(\"a:InstanceMethodCallOverloaded() -> \" .. r)\n"

        "local b = BT.Derived()\n"
        "print(b)\n"

        "local r = b:InstanceMethodGetBool()\n"
        "print(\"b:InstanceMethodGetBool() -> \" .. tostring(r))\n"

        "local r = b:InstanceMethodCallOverloaded()\n"
        "print(\"b:InstanceMethodCallOverloaded() -> \" .. r)\n"

        "local r = b:InstanceMethodGetInt()\n"
        "print(\"b:InstanceMethodGetInt() -> \" .. r)\n"

        "local c = BT.FurtherDerived()\n"
        "print(c)\n"

        "local r = c:InstanceMethodGetBool()\n"
        "print(\"c:InstanceMethodGetBool() -> \" .. tostring(r))\n"

        "local r = c:InstanceMethodCallOverloaded()\n"
        "print(\"c:InstanceMethodCallOverloaded() -> \" .. r)\n"

        "local r = c:InstanceMethodCall()\n"
        "print(\"c:InstanceMethodCall() -> \" .. r)\n"

        "local r = c:InstanceMethodGetInt()\n"
        "print(\"c:InstanceMethodGetInt() -> \" .. r)\n"

        "";


    OutputDebugStringA("Executing\n");

    if(luaL_loadstring(LuaState, Code) == LUA_OK)
    {
        if(lua_pcall(LuaState, 0, 0, 0) == LUA_OK)
        {
            lua_pop(LuaState, lua_gettop(LuaState));
            lua_gc(LuaState, LUA_GCCOLLECT);
        }
        else
        {
            const char* ErrorString = lua_tostring(LuaState, -1);

            char Buf[512];
            snprintf(Buf, 512, "Error: %s\n", ErrorString);
            OutputDebugStringA(Buf);

            lua_pop(LuaState, 1);
        }
    }

    lua_close(LuaState);

    return 0;
}

Executing
Base
BT.Base.StaticMethodCall() -> Base_StaticMethodCall
a:InstanceMethodGetInt() -> 42
a:InstanceMethodGetFloat() -> 43.0
a:InstanceMethodCall() -> Base_InstanceMethodCall
a:InstanceMethodCallOverloaded() -> Base_InstanceMethodCallOverloaded
Derived
b:InstanceMethodGetBool() -> true
b:InstanceMethodCallOverloaded() -> Derived_InstanceMethodCallOverloaded
b:InstanceMethodGetInt() -> 420
FurtherDerived
c:InstanceMethodGetBool() -> true
c:InstanceMethodCallOverloaded() -> Derived_InstanceMethodCallOverloaded
c:InstanceMethodCall() -> Base_InstanceMethodCall
c:InstanceMethodGetInt() -> 420