Function copytable

src/lua-engine.cpp:1920–1956

provides an easy way to copy a table from Lua (simple assignment only makes an alias, but sometimes an independent table is desired) currently this function only performs a shallow copy, but I think it should be changed to do a deep copy (possibly of configurable depth?) that maintains the internal table reference structure

// but I think it should be changed to do a deep copy (possibly of configurable depth?)
// that maintains the internal table reference structure
static int copytable(lua_State *L)
{
	int origIndex = 1; // we only care about the first argument
	int origType = lua_type(L, origIndex);
	if(origType == LUA_TNIL)
	{
		lua_pushnil(L);
		return 1;
	}
	if(origType != LUA_TTABLE)
	{
		luaL_typerror(L, 1, lua_typename(L, LUA_TTABLE));
		lua_pushnil(L);
		return 1;
	}

	lua_createtable(L, lua_objlen(L,1), 0);
	int copyIndex = lua_gettop(L);

	lua_pushnil(L); // first key
	int keyIndex = lua_gettop(L);
	int valueIndex = keyIndex + 1;

	while(lua_next(L, origIndex))
	{
		lua_pushvalue(L, keyIndex);
		lua_pushvalue(L, valueIndex);
		lua_rawset(L, copyIndex); // copytable[key] = value
		lua_pop(L, 1);
	}

	// copy the reference to the metatable as well, if any
	if(lua_getmetatable(L, origIndex))
		lua_setmetatable(L, copyIndex);

	return 1; // return the new table
}

// because print traditionally shows the address of tables,
// and the print function I provide instead shows the contents of tables,