Implement warning buffer pooling and control messages

src/Laylua.Tests/Tests/Library/LuaTests.cs

@@ -294,7 +294,7 @@ public unsafe void GetThread_WorksWithMultipleThreads()
     }
 
     [Test]
-    public void Warn_TriggersWarningEvent()
+    public void Warn_OnePieceMessage_TriggersWarningEvent()
     {
         // Arrange
         const string Message = "This is a warning message.";
@@ -315,7 +315,7 @@ public void Warn_TriggersWarningEvent()
     }
 
     [Test]
-    public void ContinuedWarn_TriggersSingleWarningEvent()
+    public void Warn_MultiPieceMessage_TriggersSingleWarningEvent()
     {
         // Arrange
         const string Message = "Youshallnotpass.";
@@ -335,4 +335,27 @@ public void ContinuedWarn_TriggersSingleWarningEvent()
         Assert.That(collectedMessages, Has.Count.EqualTo(1));
         Assert.That(collectedMessages[0], Is.EqualTo(Message));
     }
+
+    [Test]
+    public void Warn_OffOnControlMessages_TogglesEmitsWarningsAccordingly()
+    {
+        // Arrange
+        const string Message = "This is a warning message.";
+        var collectedMessages = new List<string>();
+
+        Lua.OpenLibrary(LuaLibraries.Standard.Base);
+        Lua.Warning += (_, e) =>
+        {
+            collectedMessages.Add(e.Message.ToString());
+        };
+
+        // Act
+        Lua.Execute("warn('@off')");
+        Lua.Execute($"warn('{Message}')");
+        Lua.Execute("warn('@on')");
+        Lua.Execute($"warn('{Message}')");
+
+        // Assert
+        Assert.That(collectedMessages, Is.EqualTo(new[] { Message }));
+    }
 }

src/Laylua/Library/Lua.cs

@@ -9,6 +9,7 @@
 using Laylua.Marshaling;
 using Laylua.Moon;
 using Qommon;
+using Qommon.Pooling;
 
 namespace Laylua;
 
@@ -64,6 +65,15 @@ public object? this[string name]
         set => SetGlobal(name, value);
     }
 
+    /// <summary>
+    ///     Gets or sets whether <see cref="Warning"/> should fire for emitted warnings.
+    /// </summary>
+    /// <remarks>
+    ///     This can be controlled by the content of warning messages;
+    ///     can be disabled using "@off" and enabled using "@on".
+    /// </remarks>
+    public bool EmitsWarnings { get; set; } = true;
+
     /// <summary>
     ///     Fired when Lua emits a warning. <br/>
     ///     See <a href="https://www.lua.org/manual/5.4/manual.html#2.3">Lua manual</a> for more information about warnings.
@@ -141,38 +151,76 @@ private Lua(
     private static void WarningHandler(void* ud, byte* msg, int tocont)
     {
         var lua = FromExtraSpace((lua_State*) ud);
-        var handlers = lua._warningHandlers;
-        if (handlers.Count == 0)
+        var msgSpan = MemoryMarshal.CreateReadOnlySpanFromNullTerminated(msg);
+        if (msgSpan.StartsWith("@"u8))
+        {
+            ProcessControlWarningMessage(lua, msgSpan[1..]);
+            return;
+        }
+
+        if (!lua.EmitsWarnings || lua._warningHandlers.Count == 0)
         {
             return;
         }
 
-        var msgSpan = MemoryMarshal.CreateReadOnlySpanFromNullTerminated(msg);
         if (tocont != 0)
         {
             (lua._warningBuffer ??= new(capacity: 128)).Write(msgSpan);
             return;
         }
 
-        ReadOnlyMemory<char> message;
+        RentedArray<char> message;
         var warningBuffer = lua._warningBuffer;
-        if (warningBuffer == null)
+        if (warningBuffer == null || warningBuffer.Length == 0)
         {
-            message = Encoding.UTF8.GetString(msgSpan).AsMemory();
+            message = CreateWarningMessage(msgSpan);
         }
         else
         {
             warningBuffer.Write(msgSpan);
             Debug.Assert(warningBuffer.TryGetBuffer(out var buffer));
-            message = Encoding.UTF8.GetString(buffer).AsMemory();
 
-            warningBuffer.Position = 0;
-            warningBuffer.SetLength(0);
+            message = CreateWarningMessage(buffer);
+
+            ClearWarningBuffer(warningBuffer);
+        }
+
+        using (message)
+        {
+            foreach (var handler in lua._warningHandlers)
+            {
+                handler.Invoke(lua, new LuaWarningEventArgs(message));
+            }
+        }
+
+        static void ProcessControlWarningMessage(Lua lua, ReadOnlySpan<byte> controlMsg)
+        {
+            if (controlMsg.SequenceEqual("on"u8))
+            {
+                lua.EmitsWarnings = true;
+            }
+            else if (controlMsg.SequenceEqual("off"u8))
+            {
+                lua.EmitsWarnings = false;
+
+                if (lua._warningBuffer != null)
+                {
+                    ClearWarningBuffer(lua._warningBuffer);
+                }
+            }
+        }
+
+        static RentedArray<char> CreateWarningMessage(ReadOnlySpan<byte> msg)
+        {
+            var message = RentedArray<char>.Rent(Encoding.UTF8.GetCharCount(msg));
+            _ = Encoding.UTF8.GetChars(msg, message);
+            return message;
         }
 
-        foreach (var handler in handlers)
+        static void ClearWarningBuffer(MemoryStream warningBuffer)
         {
-            handler.Invoke(lua, new LuaWarningEventArgs(message));
+            warningBuffer.Position = 0;
+            warningBuffer.SetLength(0);
         }
     }