Node definition aliases

src/nodedef.cpp

@@ -398,8 +398,18 @@ public:
 	{
 		return get(n.getContent());
 	}
-	virtual bool getId(const std::string &name, content_t &result) const
+	virtual bool getId(const std::string &name_, content_t &result) const
 	{
+		std::string name = name_;
+		// Convert name according to possible alias
+		std::map<std::string, std::string>::const_iterator i;
+		i = m_aliases.find(name);
+		if(i != m_aliases.end()){
+			/*infostream<<"ndef: alias active: "<<name<<" -> "<<i->second
+					<<std::endl;*/
+			name = i->second;
+		}
+		// Get id
 		return m_name_id_mapping.getId(name, result);
 	}
 	virtual content_t getId(const std::string &name) const
@@ -438,6 +448,12 @@ public:
 		m_content_features[c] = def;
 		if(def.name != "")
 			m_name_id_mapping.set(c, def.name);
+
+		// Remove conflicting alias if it exists
+		bool alias_removed = (m_aliases.erase(def.name) != 0);
+		if(alias_removed)
+			infostream<<"ndef: erased alias "<<def.name
+					<<" because node was defined"<<std::endl;
 	}
 	virtual content_t set(const std::string &name,
 			const ContentFeatures &def)
@@ -476,6 +492,19 @@ public:
 		f.material.diggability = DIGGABLE_NORMAL;
 		return set(name, f);
 	}
+	virtual void setAlias(const std::string &name,
+			const std::string &convert_to)
+	{
+		content_t id;
+		if(getId(name, id)){
+			infostream<<"ndef: not setting alias "<<name<<" -> "<<convert_to
+					<<": "<<name<<" is already defined"<<std::endl;
+			return;
+		}
+		infostream<<"ndef: setting alias "<<name<<" -> "<<convert_to
+				<<std::endl;
+		m_aliases[name] = convert_to;
+	}
 	virtual void updateTextures(ITextureSource *tsrc)
 	{
 #ifndef SERVER
@@ -639,8 +668,12 @@ public:
 		}
 	}
 private:
+	// Features indexed by id
 	ContentFeatures m_content_features[MAX_CONTENT+1];
+	// A mapping for fast converting back and forth between names and ids
 	NameIdMapping m_name_id_mapping;
+	// Aliases for loading legacy crap
+	std::map<std::string, std::string> m_aliases;
 };
 
 IWritableNodeDefManager* createNodeDefManager()

src/nodedef.h

@@ -279,6 +279,11 @@ public:
 			const ContentFeatures &def)=0;
 	// If returns CONTENT_IGNORE, could not allocate id
 	virtual content_t allocateDummy(const std::string &name)=0;
+	// Set an alias so that nodes named <name> will load as <convert_to>.
+	// Alias is not set if <name> has already been defined.
+	// Alias will be removed if <name> is defined at a later point of time.
+	virtual void setAlias(const std::string &name,
+			const std::string &convert_to)=0;
 
 	/*
 		Update tile textures to latest return values of TextueSource.

src/scriptapi.cpp

@@ -1122,6 +1122,24 @@ static int l_register_node(lua_State *L)
 	return 0; /* number of results */
 }
 
+// alias_node(name, convert_to_name)
+static int l_alias_node(lua_State *L)
+{
+	std::string name = luaL_checkstring(L, 1);
+	std::string convert_to = luaL_checkstring(L, 2);
+
+	// Get server from registry
+	lua_getfield(L, LUA_REGISTRYINDEX, "minetest_server");
+	Server *server = (Server*)lua_touserdata(L, -1);
+	// And get the writable node definition manager from the server
+	IWritableNodeDefManager *nodedef =
+			server->getWritableNodeDefManager();
+	
+	nodedef->setAlias(name, convert_to);
+	
+	return 0; /* number of results */
+}
+
 // register_craft({output=item, recipe={{item00,item10},{item01,item11}})
 static int l_register_craft(lua_State *L)
 {
@@ -1274,6 +1292,7 @@ static const struct luaL_Reg minetest_f [] = {
 	{"register_node", l_register_node},
 	{"register_craft", l_register_craft},
 	{"register_abm", l_register_abm},
+	{"alias_node", l_alias_node},
 	{"setting_get", l_setting_get},
 	{"setting_getbool", l_setting_getbool},
 	{"chat_send_all", l_chat_send_all},