LuaUtility.cs

~ Move Regex for format parts to a GeneratedRegex function to improve performance.
~ Only read the LuaVM template once, as it is read from the resources on every subsequent use.
~ Account for the absence of the LuaVM in results.

services/grid-bot/lib/utility/Implementation/LuaUtility.cs

@@ -14,40 +14,53 @@
 /// <summary>
 /// Utility for interacting with grid-server Lua.
 /// </summary>
-public class LuaUtility : ILuaUtility
+public partial class LuaUtility : ILuaUtility
 {
     private static readonly Assembly _assembly = Assembly.GetExecutingAssembly();
     private const string _luaVmResource = "Grid.Bot.Lua.LuaVMTemplate.lua";
 
-    private static string FixFormatString(string input)
+    [GeneratedRegex(@"{{(\d{1,2})}}", RegexOptions.IgnoreCase | RegexOptions.Compiled)]
+    private static partial Regex FormatPartRegex();
+
+
+    private static readonly string _LuaVM;
+
+    static LuaUtility()
     {
-        //language=regex
-        const string partRegex = @"{{(\d{1,2})}}";
+        using var stream = _assembly.GetManifestResourceStream(_luaVmResource);
+        using var reader = new StreamReader(stream);
 
+        _LuaVM = FixFormatString(reader.ReadToEnd());
+    }
+
+    private static string FixFormatString(string input)
+    {
         input = input.Replace("{", "{{");
         input = input.Replace("}", "}}");
 
-        input = Regex.Replace(input, partRegex, (m) => { return $"{{{m.Groups[1]}}}"; });
+        input = FormatPartRegex().Replace(input, (m) => { return $"{{{m.Groups[1]}}}"; });
 
         return input;
     }
 
     /// <inheritdoc cref="ILuaUtility.LuaVMTemplate"/>
-    public string LuaVMTemplate
-    {
-        get {
-            using var stream = _assembly.GetManifestResourceStream(_luaVmResource);
-            using var reader = new StreamReader(stream);
-
-            return FixFormatString(reader.ReadToEnd());
-        }
-    }
+    public string LuaVMTemplate => _LuaVM;
 
     /// <inheritdoc cref="ILuaUtility.ParseResult(IEnumerable{LuaValue})"/>
     public (string result, ReturnMetadata metadata) ParseResult(IEnumerable<LuaValue> result)
     {
+        if (result.Count() == 1)
+        {
+            // Legacy case, where LuaVM is not enabled.
+
+            var mockMetadata = new ReturnMetadata();
+            mockMetadata.Success = true;
+
+            return ((string)Lua.ConvertLua(result.First()), mockMetadata);
+        }
+
         return (
-            (string)Lua.ConvertLua(result.FirstOrDefault()), 
+            (string)Lua.ConvertLua(result.FirstOrDefault()),
             JsonConvert.DeserializeObject<ReturnMetadata>((string)Lua.ConvertLua(result.ElementAtOrDefault(1)))
         );
     }