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#ifndef _LUA_METATABLE_H_
#define _LUA_METATABLE_H_
#include <functional>
#define LUA_TINTEGER LUA_NUMTAGS + 1
#define LUA_TSTRINGA LUA_NUMTAGS + 2
#define LUA_TSTRINGW LUA_NUMTAGS + 3
template<typename T>
class MTField : public MZeroedObject
{
private:
enum MTFieldGetter
{
MTFG_LAMBDA = 1,
MTFG_OFFSET = 2
};
size_t offset;
size_t size;
int type;
int getterType;
std::function<void*(T*)> lambda;
public:
MTField(size_t offset, size_t size, int type)
: offset(offset), size(size), type(type), getterType(MTFG_OFFSET) { }
MTField(std::function<void*(T*)> f, int type)
: lambda(f), type(type), getterType(MTFG_LAMBDA) { }
int GetType() const { return type; }
template<typename R>
R GetValue(T *obj) const
{
if (getterType == MTFG_LAMBDA) return (R)lambda(obj);
else
{
R res = NULL;
memcpy(&res, ((char*)obj) + offset, size);
return res;
}
}
};
template<typename T>
class MT
{
private:
lua_State *L;
static const char *name;
static std::map<std::string, MTField<T>*> fields;
static void Init(lua_State *L, T **obj)
{
luaL_checktype(L, 1, LUA_TLIGHTUSERDATA);
*obj = (T*)lua_touserdata(L, 1);
}
static int Index(lua_State *L, T* /*obj*/)
{
lua_pushnil(L);
return 1;
}
static void Free(lua_State* /*L*/, T **obj)
{
*obj = NULL;
}
static int lua__new(lua_State *L)
{
T **udata = (T**)lua_newuserdata(L, sizeof(T*));
Init(L, udata);
if (*udata == NULL)
{
lua_pushnil(L);
return 1;
}
luaL_setmetatable(L, MT::name);
return 1;
}
static int lua__call(lua_State *L)
{
int nargs = lua_gettop(L);
lua_pushcfunction(L, lua__new);
for (int i = 2; i <= nargs; i++)
lua_pushvalue(L, i);
luaM_pcall(L, nargs - 1, 1);
return 1;
}
static int lua__bnot(lua_State *L)
{
T *obj = *(T**)luaL_checkudata(L, 1, MT::name);
lua_pushlightuserdata(L, obj);
return 1;
}
static int lua__index(lua_State *L)
{
T *obj = *(T**)luaL_checkudata(L, 1, MT::name);
const char *key = lua_tostring(L, 2);
auto it = fields.find(key);
if (it == fields.end())
{
return Index(L, obj);
}
MTField<T> *field = it->second;
switch (field->GetType())
{
case LUA_TBOOLEAN:
lua_pushboolean(L, field->GetValue<int>(obj));
break;
case LUA_TINTEGER:
lua_pushinteger(L, field->GetValue<long long>(obj));
break;
case LUA_TNUMBER:
lua_pushnumber(L, field->GetValue<intptr_t>(obj));
break;
case LUA_TSTRING:
lua_pushstring(L, field->GetValue<char*>(obj));
break;
case LUA_TSTRINGA:
lua_pushstring(L, ptrA(mir_utf8encode(field->GetValue<char*>(obj))));
break;
case LUA_TSTRINGW:
lua_pushstring(L, T2Utf(field->GetValue<wchar_t*>(obj)));
break;
case LUA_TLIGHTUSERDATA:
lua_pushlightuserdata(L, field->GetValue<void*>(obj));
break;
default:
lua_pushnil(L);
}
return 1;
}
static int lua__gc(lua_State *L)
{
T **obj = (T**)luaL_checkudata(L, 1, MT::name);
MT::Free(L, obj);
return 0;
}
public:
MT(lua_State *L, const char *tname) : L(L)
{
MT::name = tname;
luaL_newmetatable(L, MT::name);
lua_pushcfunction(L, lua__call);
lua_setfield(L, -2, "__call");
lua_pushcfunction(L, lua__index);
lua_setfield(L, -2, "__index");
lua_pushcfunction(L, lua__bnot);
lua_setfield(L, -2, "__bnot");
lua_pushcfunction(L, lua__gc);
lua_setfield(L, -2, "__gc");
lua_pop(L, 1);
lua_createtable(L, 0, 1);
lua_pushcfunction(L, lua__new);
lua_setfield(L, -2, "new");
lua_pushvalue(L, -1);
lua_setglobal(L, MT::name);
luaL_setmetatable(L, MT::name);
lua_pop(L, 1);
}
template<typename R>
MT& Field(R T::*M, const char *name, int type, size_t size = 0)
{
if (size == 0)
size = sizeof(M);
size_t offset = offsetof(T, *M);
if (type != LUA_TNONE)
fields[name] = new MTField<T>(offset, size, type);
return *this;
}
template<typename L>
MT& Field(const L &f, const char *name, int type)
{
if (type != LUA_TNONE)
fields[name] = new MTField<T>(f, type);
return *this;
}
static void Set(lua_State *L, T *obj)
{
if (obj == NULL)
{
lua_pushnil(L);
return;
}
T **udata = (T**)lua_newuserdata(L, sizeof(T));
*udata = obj;
luaL_setmetatable(L, MT::name);
}
};
template<typename T>
const char *MT<T>::name;
template<typename T>
std::map<std::string, MTField<T>*> MT<T>::fields;
#endif //_LUA_METATABLE_H_
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