Add ModMetadata API (#5131)

* mod can create a ModMetadata object where store its values and retrieve it.
* Modmetadata object can only be fetched at mod loading
* Save when modified using same time as map interval or at server stop
* add helper function to get mod storage path
* ModMetadata has exactly same calls than all every other Metadata

1 files changed, 143 insertions, 0 deletions

diff --git a/src/script/lua_api/l_storage.cpp b/src/script/lua_api/l_storage.cpp
new file mode 100644
index 000000000..42928255f
--- /dev/null
+++ b/src/script/lua_api/l_storage.cpp
@@ -0,0 +1,143 @@
+/*
+Minetest
+Copyright (C) 2013 celeron55, Perttu Ahola <celeron55@gmail.com>
+Copyright (C) 2017 nerzhul, Loic Blot <loic.blot@unix-experience.fr>
+
+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_storage.h"
+#include "l_internal.h"
+#include "mods.h"
+#include "server.h"
+
+int ModApiStorage::l_get_mod_storage(lua_State *L)
+{
+	lua_rawgeti(L, LUA_REGISTRYINDEX, CUSTOM_RIDX_CURRENT_MOD_NAME);
+	if (!lua_isstring(L, -1)) {
+		return 0;
+	}
+
+	std::string mod_name = lua_tostring(L, -1);
+
+	ModMetadata *store = new ModMetadata(mod_name);
+	// For server side
+	if (Server *server = getServer(L)) {
+		store->load(server->getModStoragePath());
+		server->registerModStorage(store);
+	} else {
+		assert(false); // this should not happen
+	}
+
+	StorageRef::create(L, store);
+	int object = lua_gettop(L);
+
+	lua_pushvalue(L, object);
+	return 1;
+}
+
+void ModApiStorage::Initialize(lua_State *L, int top)
+{
+	API_FCT(get_mod_storage);
+}
+
+StorageRef::StorageRef(ModMetadata *object):
+	m_object(object)
+{
+}
+
+void StorageRef::create(lua_State *L, ModMetadata *object)
+{
+	StorageRef *o = new StorageRef(object);
+	*(void **)(lua_newuserdata(L, sizeof(void *))) = o;
+	luaL_getmetatable(L, className);
+	lua_setmetatable(L, -2);
+}
+
+int StorageRef::gc_object(lua_State *L)
+{
+	StorageRef *o = *(StorageRef **)(lua_touserdata(L, 1));
+	// Server side
+	if (Server *server = getServer(L))
+		server->unregisterModStorage(getobject(o)->getModName());
+	delete o;
+	return 0;
+}
+
+void StorageRef::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_pop(L, 1);  // drop metatable
+
+	luaL_openlib(L, 0, methods, 0);  // fill methodtable
+	lua_pop(L, 1);  // drop methodtable
+}
+
+StorageRef* StorageRef::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 *(StorageRef**)ud;  // unbox pointer
+}
+
+ModMetadata* StorageRef::getobject(StorageRef *ref)
+{
+	ModMetadata *co = ref->m_object;
+	return co;
+}
+
+Metadata* StorageRef::getmeta(bool auto_create)
+{
+	return m_object;
+}
+
+void StorageRef::clearMeta()
+{
+	m_object->clear();
+}
+
+const char StorageRef::className[] = "StorageRef";
+const luaL_reg StorageRef::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),
+	{0,0}
+};