Micro-optimizations for pushing strings to Lua

Use lua_pushliteral and lua_pushlstring instead of lua_pushstring, which
avoids Lua having to determine the length of the string.

4 files changed, 29 insertions, 37 deletions

diff --git a/src/scripting/lua.cpp b/src/scripting/lua.cpp
index c0aedfdd..545e365e 100644
--- a/src/scripting/lua.cpp
+++ b/src/scripting/lua.cpp
@@ -458,8 +458,6 @@ static int chr_get_inventory(lua_State *s)
     int firstTableStackPosition = lua_gettop(s);
     int tableIndex = 1;
 
-    std::string itemName = "";
-
     for (InventoryData::const_iterator it = invData.begin(),
         it_end = invData.end(); it != it_end; ++it)
     {
@@ -470,20 +468,19 @@ static int chr_get_inventory(lua_State *s)
         lua_createtable(s, 0, 4);
         int subTableStackPosition = lua_gettop(s);
         // Stores the item info in it.
-        lua_pushstring(s, "slot");
+        lua_pushliteral(s, "slot");
         lua_pushinteger(s, it->first); // The slot id
         lua_settable(s, subTableStackPosition);
 
-        lua_pushstring(s, "id");
+        lua_pushliteral(s, "id");
         lua_pushinteger(s, it->second.itemId);
         lua_settable(s, subTableStackPosition);
 
-        lua_pushstring(s, "name");
-        itemName = itemManager->getItem(it->second.itemId)->getName();
-        lua_pushstring(s, itemName.c_str());
+        lua_pushliteral(s, "name");
+        push(s, itemManager->getItem(it->second.itemId)->getName());
         lua_settable(s, subTableStackPosition);
 
-        lua_pushstring(s, "amount");
+        lua_pushliteral(s, "amount");
         lua_pushinteger(s, it->second.amount);
         lua_settable(s, subTableStackPosition);
 
@@ -517,7 +514,6 @@ static int chr_get_equipment(lua_State *s)
     int firstTableStackPosition = lua_gettop(s);
     int tableIndex = 1;
 
-    std::string itemName;
     std::set<unsigned> itemInstances;
 
     for (EquipData::const_iterator it = equipData.begin(),
@@ -534,17 +530,16 @@ static int chr_get_equipment(lua_State *s)
         lua_createtable(s, 0, 3);
         int subTableStackPosition = lua_gettop(s);
         // Stores the item info in it.
-        lua_pushstring(s, "slot");
+        lua_pushliteral(s, "slot");
         lua_pushinteger(s, it->first); // The slot id
         lua_settable(s, subTableStackPosition);
 
-        lua_pushstring(s, "id");
+        lua_pushliteral(s, "id");
         lua_pushinteger(s, it->second.itemId);
         lua_settable(s, subTableStackPosition);
 
-        lua_pushstring(s, "name");
-        itemName = itemManager->getItem(it->second.itemId)->getName();
-        lua_pushstring(s, itemName.c_str());
+        lua_pushliteral(s, "name");
+        push(s, itemManager->getItem(it->second.itemId)->getName());
         lua_settable(s, subTableStackPosition);
 
         // Add the sub-table as value of the main one.
@@ -1127,7 +1122,7 @@ static int being_remove_attribute_modifier(lua_State *s)
 static int being_get_name(lua_State *s)
 {
     Being *being = checkBeing(s, 1);
-    lua_pushstring(s, being->getName().c_str());
+    push(s, being->getName());
     return 1;
 }
 
@@ -1309,7 +1304,7 @@ static int monster_get_name(lua_State *s)
         luaL_error(s, "monster_get_name called with unknown monster id.");
         return 0;
     }
-    lua_pushstring(s, spec->getName().c_str());
+    push(s, spec->getName());
     return 1;
 }
 
@@ -1386,7 +1381,7 @@ static int chr_get_quest(lua_State *s)
     bool res = getQuestVar(q, name, value);
     if (res)
     {
-        lua_pushstring(s, value.c_str());
+        push(s, value);
         return 1;
     }
     QuestCallback *f = new QuestThreadCallback(&LuaScript::getQuestCallback,
@@ -1453,7 +1448,7 @@ static int chr_try_get_quest(lua_State *s)
     std::string value;
     bool res = getQuestVar(q, name, value);
     if (res)
-        lua_pushstring(s, value.c_str());
+        push(s, value);
     else
         lua_pushnil(s);
     return 1;
@@ -1469,9 +1464,8 @@ static int getvar_map(lua_State *s)
     luaL_argcheck(s, name[0] != 0, 1, "empty variable name");
 
     MapComposite *map = checkCurrentMap(s);
-    std::string value = map->getVariable(name);
 
-    lua_pushstring(s, value.c_str());
+    push(s, map->getVariable(name));
     return 1;
 }
 
@@ -1500,8 +1494,7 @@ static int getvar_world(lua_State *s)
     const char *name = luaL_checkstring(s, 1);
     luaL_argcheck(s, name[0] != 0, 1, "empty variable name");
 
-    std::string value = GameState::getVariable(name);
-    lua_pushstring(s, value.c_str());
+    push(s, GameState::getVariable(name));
     return 1;
 }
 
@@ -2128,8 +2121,7 @@ static int get_map_property(lua_State *s)
     const char *property = luaL_checkstring(s, 1);
     Map *map = checkCurrentMap(s)->getMap();
 
-    std::string value = map->getProperty(property);
-    lua_pushstring(s, value.c_str());
+    push(s, map->getProperty(property));
     return 1;
 }
 
@@ -2210,7 +2202,7 @@ static int item_get_name(lua_State *s)
         luaL_error(s, "item_get_name called with unknown item id.");
         return 0;
     }
-    lua_pushstring(s, it->getName().c_str());
+    push(s, it->getName());
     return 1;
 }
 
@@ -2314,7 +2306,7 @@ static int map_object_get_property(lua_State *s)
     std::string property = obj->getProperty(key);
     if (!property.empty())
     {
-        lua_pushstring(s, property.c_str());
+        push(s, property);
         return 1;
     }
     else
@@ -2346,7 +2338,7 @@ static int map_object_get_bounds(lua_State *s)
 static int map_object_get_name(lua_State *s)
 {
     MapObject *obj = LuaMapObject::check(s, 1);
-    lua_pushstring(s, obj->getName().c_str());
+    push(s, obj->getName());
     return 1;
 }
 
@@ -2357,7 +2349,7 @@ static int map_object_get_name(lua_State *s)
 static int map_object_get_type(lua_State *s)
 {
     MapObject *obj = LuaMapObject::check(s, 1);
-    lua_pushstring(s, obj->getType().c_str());
+    push(s, obj->getType());
     return 1;
 }
 
@@ -2398,7 +2390,7 @@ static int get_special_info(lua_State *s)
 static int specialinfo_get_name(lua_State *s)
 {
     SpecialManager::SpecialInfo *info = LuaSpecialInfo::check(s, 1);
-    lua_pushstring(s, info->name.c_str());
+    push(s, info->name);
     return 1;
 }
 
@@ -2419,7 +2411,7 @@ static int specialinfo_is_rechargeable(lua_State *s)
 static int specialinfo_get_category(lua_State *s)
 {
     SpecialManager::SpecialInfo *info = LuaSpecialInfo::check(s, 1);
-    lua_pushstring(s, info->setName.c_str());
+    push(s, info->setName);
     return 1;
 }
 
@@ -2559,7 +2551,7 @@ static int require_loader(lua_State *s)
     if (!path.empty())
         luaL_loadfile(s, path.c_str());
     else
-        lua_pushstring(s, "File not found");
+        lua_pushliteral(s, "File not found");
 
     return 1;
 }
@@ -2573,7 +2565,7 @@ LuaScript::LuaScript():
     luaL_openlibs(mRootState);
 
     // Register package loader that goes through the resource manager
-    // table.insert(package.loaders, 2, require_loader)
+    // package.loaders[2] = require_loader
     lua_getglobal(mRootState, "package");
 #if LUA_VERSION_NUM < 502
     lua_getfield(mRootState, -1, "loaders");
diff --git a/src/scripting/luascript.cpp b/src/scripting/luascript.cpp
index a3dcb1d4..4104bc89 100644
--- a/src/scripting/luascript.cpp
+++ b/src/scripting/luascript.cpp
@@ -82,7 +82,7 @@ void LuaScript::push(int v)
 void LuaScript::push(const std::string &v)
 {
     assert(nbArgs >= 0);
-    lua_pushstring(mCurrentState, v.c_str());
+    lua_pushlstring(mCurrentState, v.c_str(), v.length());
     ++nbArgs;
 }
 
diff --git a/src/scripting/luautil.cpp b/src/scripting/luautil.cpp
index 3de23c77..f7b39e29 100644
--- a/src/scripting/luautil.cpp
+++ b/src/scripting/luautil.cpp
@@ -86,8 +86,8 @@ void UserDataCache::insert(lua_State *s, void *object)
 
         // The metatable that makes the values in the table above weak
         lua_newtable(s);                        // UD, Cache, {}
-        lua_pushstring(s, "__mode");
-        lua_pushstring(s, "v");
+        lua_pushliteral(s, "__mode");
+        lua_pushliteral(s, "v");
         lua_rawset(s, -3);                      // UD, Cache, { __mode = "v" }
         lua_setmetatable(s, -2);                // UD, Cache
 
diff --git a/src/scripting/luautil.h b/src/scripting/luautil.h
index 0d2a981d..8e380d4e 100644
--- a/src/scripting/luautil.h
+++ b/src/scripting/luautil.h
@@ -102,7 +102,7 @@ public:
         mTypeName = typeName;
 
         luaL_newmetatable(s, mTypeName);        // metatable
-        lua_pushstring(s, "__index");           // metatable, "__index"
+        lua_pushliteral(s, "__index");          // metatable, "__index"
         lua_createtable(s, 0, 0);               // metatable, "__index", {}
 #if LUA_VERSION_NUM < 502
         luaL_register(s, NULL, members);
@@ -197,7 +197,7 @@ inline void push(lua_State *s, int val)
 
 inline void push(lua_State *s, const std::string &val)
 {
-    lua_pushstring(s, val.c_str());
+    lua_pushlstring(s, val.c_str(), val.length());
 }
 
 inline void push(lua_State *s, Entity *val)