C++ Lua wrapper

gistfile1.cpp

#include <lua.hpp>


class Lua {
public:
	static class Nil { Nil(); } nil;

	Lua() {
		L=luaL_newstate();
	}

	~Lua() {
		lua_close(L);
	}

	operator lua_State*() {
		return L;
	}

	bool istable(int index) {
		return lua_istable(L, index);
	}


	template <typename T>
	bool is(int index);

	template <typename T>
	T to(int index);

	template <typename T>
	T getfield(int index, const char* name) {
		lua_getfield(L, index, name);
		T result = to<T>(-1);
		pop();
		return result;
	}

	int gettop() {
		return lua_gettop(L);
	}

	void pushnil() {
		lua_pushnil(L);
	}

	void pop(int n=1) {
		lua_pop(L, n);
	}

protected:
	lua_State   *L;
};

template<>
bool Lua::is<Lua::Nil>(int index) {
	return lua_isnil(L, index);
}

template<>
bool Lua::is<bool>(int index) {
	return lua_isboolean(L, index);
}


template<>
bool Lua::is<std::string>(int index) {
	return lua_isstring(L, index);
}


template<>
bool Lua::is<const char*>(int index) {
	return lua_isstring(L, index);
}


template<>
bool Lua::to<bool>(int index) {
	return lua_toboolean(L, index);
}


template<>
int Lua::to<int>(int index) {
	return lua_tointeger(L, index);
}


template<>
double Lua::to<double>(int index) {
	return lua_tonumber(L, index);
}



template <>
const char* Lua::to<const char*>(int index) {
	return lua_tostring(L, index);
}


template <>
std::string Lua::to<std::string>(int index) {
	size_t height;
	const char* buf;

	if ((buf=lua_tolstring(L, index, &height))==NULL)
		return std::string();
	return std::string(buf, height);
}


Lua& operator<<(Lua& lua, const Lua::Nil nil) {
	lua_pushnil(lua);
	return lua;
}


Lua& operator<<(Lua& lua, bool value) {
	lua_pushboolean(lua, static_cast<int>(value));
	return lua;
}


Lua& operator<<(Lua& lua, int value) {
	lua_pushinteger(lua, value);
	return lua;
}


Lua& operator<<(Lua& lua, double value) {
	lua_pushnumber(lua, value);
	return lua;
}


Lua& operator<<(Lua& lua, const char* value) {
	lua_pushlstring(lua, value, strlen(value));
	return lua;
}


Lua& operator<<(Lua& lua, const std::string &value) {
	lua_pushlstring(lua, value.c_str(), value.length());
	return lua;
}