Replace stringstream subdirectory map id parsing

Author: Foereaper

ElunaLoader.cpp

@@ -12,6 +12,7 @@
 #include <fstream>
 #include <sstream>
 #include <thread>
+#include <charconv>
 
 #if defined USING_BOOST
 #include <boost/filesystem.hpp>
@@ -215,25 +216,18 @@ void ElunaLoader::ReadFiles(lua_State* L, std::string path)
 
             if (fs::is_regular_file(dir_iter->status()))
             {
-                int32 mapId;
+                // default to all maps
+                int32 mapId = -1;
 
                 // strip base folder path and trailing slash from fullpath
                 std::string subfolder = dir_iter->path().generic_string();
                 subfolder = subfolder.erase(0, lua_folderpath.size() + 1);
 
-                // stringstream used for conversion
-                std::stringstream ss;
+                // convert subfolder name to an integer
+                auto [ptr, ec] = std::from_chars(subfolder.data(), subfolder.data() + subfolder.size(), mapId);
 
-                // push subfolder int to subMapId
-                ss << subfolder;
-                ss >> mapId;
-
-                // if this failed, then we load the script for all maps
-                if (ss.fail())
-                    mapId = -1;
-
-                // just in case we have a subfolder named an int less than all..
-                if (mapId < -1)
+                // default to all maps on invalid map id or map id less than -1
+                if (ec == std::errc::invalid_argument || ec == std::errc::result_out_of_range || mapId < -1)
                     mapId = -1;
 
                 // was file, try add