Add player:get_meta(), deprecate player attributes (#7202)

* Add player:get_meta(), deprecate player attributes

src/script/lua_api/l_playermeta.cpp

@@ -0,0 +1,121 @@
+/*
+Minetest
+Copyright (C) 2013 celeron55, Perttu Ahola <celeron55@gmail.com>
+Copyright (C) 2017-8 rubenwardy <rw@rubenwardy.com>
+
+This program is free software; you can redistribute it and/or modify
+it under the terms of the GNU Lesser General Public License as published by
+the Free Software Foundation; either version 2.1 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU Lesser General Public License for more details.
+
+You should have received a copy of the GNU Lesser General Public License along
+with this program; if not, write to the Free Software Foundation, Inc.,
+51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+*/
+
+#include "lua_api/l_playermeta.h"
+#include "lua_api/l_internal.h"
+#include "common/c_content.h"
+
+/*
+	PlayerMetaRef
+*/
+PlayerMetaRef *PlayerMetaRef::checkobject(lua_State *L, int narg)
+{
+	luaL_checktype(L, narg, LUA_TUSERDATA);
+	void *ud = luaL_checkudata(L, narg, className);
+	if (!ud)
+		luaL_typerror(L, narg, className);
+
+	return *(PlayerMetaRef **)ud; // unbox pointer
+}
+
+Metadata *PlayerMetaRef::getmeta(bool auto_create)
+{
+	return metadata;
+}
+
+void PlayerMetaRef::clearMeta()
+{
+	metadata->clear();
+}
+
+void PlayerMetaRef::reportMetadataChange()
+{
+	// TODO
+}
+
+// garbage collector
+int PlayerMetaRef::gc_object(lua_State *L)
+{
+	PlayerMetaRef *o = *(PlayerMetaRef **)(lua_touserdata(L, 1));
+	delete o;
+	return 0;
+}
+
+// Creates an PlayerMetaRef and leaves it on top of stack
+// Not callable from Lua; all references are created on the C side.
+void PlayerMetaRef::create(lua_State *L, Metadata *metadata)
+{
+	PlayerMetaRef *o = new PlayerMetaRef(metadata);
+	*(void **)(lua_newuserdata(L, sizeof(void *))) = o;
+	luaL_getmetatable(L, className);
+	lua_setmetatable(L, -2);
+}
+
+void PlayerMetaRef::Register(lua_State *L)
+{
+	lua_newtable(L);
+	int methodtable = lua_gettop(L);
+	luaL_newmetatable(L, className);
+	int metatable = lua_gettop(L);
+
+	lua_pushliteral(L, "__metatable");
+	lua_pushvalue(L, methodtable);
+	lua_settable(L, metatable); // hide metatable from Lua getmetatable()
+
+	lua_pushliteral(L, "metadata_class");
+	lua_pushlstring(L, className, strlen(className));
+	lua_settable(L, metatable);
+
+	lua_pushliteral(L, "__index");
+	lua_pushvalue(L, methodtable);
+	lua_settable(L, metatable);
+
+	lua_pushliteral(L, "__gc");
+	lua_pushcfunction(L, gc_object);
+	lua_settable(L, metatable);
+
+	lua_pushliteral(L, "__eq");
+	lua_pushcfunction(L, l_equals);
+	lua_settable(L, metatable);
+
+	lua_pop(L, 1); // drop metatable
+
+	luaL_openlib(L, 0, methods, 0);
+	lua_pop(L, 1);
+
+	// Cannot be created from Lua
+	// lua_register(L, className, create_object);
+}
+
+// clang-format off
+const char PlayerMetaRef::className[] = "PlayerMetaRef";
+const luaL_Reg PlayerMetaRef::methods[] = {
+	luamethod(MetaDataRef, get_string),
+	luamethod(MetaDataRef, set_string),
+	luamethod(MetaDataRef, get_int),
+	luamethod(MetaDataRef, set_int),
+	luamethod(MetaDataRef, get_float),
+	luamethod(MetaDataRef, set_float),
+	luamethod(MetaDataRef, to_table),
+	luamethod(MetaDataRef, from_table),
+	luamethod(MetaDataRef, equals),
+	{0,0}
+};
+// clang-format on