feat: generate serializers for IMessageBase structs (#1353)

* Allow Weaver to add bodies to IMessageBase structs with empty de/serialize methods

* Update Assets/Mirror/Editor/Weaver/Processors/MessageClassProcessor.cs

Co-Authored-By: Paul Pacheco <paulpach@gmail.com>

* applied suggested changes

* adjusted empty method check

* Update Assets/Mirror/Editor/Weaver/Processors/MessageClassProcessor.cs

formatting

Co-Authored-By: vis2k <info@noobtuts.com>

Co-authored-by: Paul Pacheco <paulpach@gmail.com>
Co-authored-by: vis2k <info@noobtuts.com>

Assets/Mirror/Editor/Weaver/Processors/MessageClassProcessor.cs

@@ -1,4 +1,6 @@
 // this class generates OnSerialize/OnDeserialize when inheriting from MessageBase
+
+using System.Linq;
 using Mono.CecilX;
 using Mono.CecilX.Cil;
 
@@ -6,6 +8,12 @@ namespace Mirror.Weaver
 {
     static class MessageClassProcessor
     {
+
+        static bool IsEmptyDefault(this MethodBody body)
+        {
+            return body.Instructions.All(instruction => instruction.OpCode == OpCodes.Nop || instruction.OpCode == OpCodes.Ret);
+        }
+
         public static void Process(TypeDefinition td)
         {
             Weaver.DLog(td, "MessageClassProcessor Start");
@@ -23,9 +31,9 @@ public static void Process(TypeDefinition td)
         static void GenerateSerialization(TypeDefinition td)
         {
             Weaver.DLog(td, "  GenerateSerialization");
-            foreach (MethodDefinition m in td.Methods)
+            MethodDefinition existingMethod = td.Methods.FirstOrDefault(md=>md.Name == "Serialize");
+            if (existingMethod != null && !existingMethod.Body.IsEmptyDefault())
             {
-                if (m.Name == "Serialize")
                 return;
             }
 
@@ -44,13 +52,22 @@ static void GenerateSerialization(TypeDefinition td)
                 }
             }
 
-            MethodDefinition serializeFunc = new MethodDefinition("Serialize",
+            MethodDefinition serializeFunc = existingMethod ?? new MethodDefinition("Serialize",
                     MethodAttributes.Public | MethodAttributes.Virtual | MethodAttributes.HideBySig,
                     Weaver.voidType);
 
+            if (existingMethod == null) //only add to new method
+            {
                 serializeFunc.Parameters.Add(new ParameterDefinition("writer", ParameterAttributes.None, Weaver.CurrentAssembly.MainModule.ImportReference(Weaver.NetworkWriterType)));
+            }
             ILProcessor serWorker = serializeFunc.Body.GetILProcessor();
+            if (existingMethod != null)
+            {
+                serWorker.Body.Instructions.Clear(); //remove default nop&ret from existing empty interface method
+            }
 
+            if (!td.IsValueType) //if not struct(IMessageBase), likely same as using else {} here in all cases
+            {
                 // call base
                 MethodReference baseSerialize = Resolvers.ResolveMethodInParents(td.BaseType, Weaver.CurrentAssembly, "Serialize");
                 if (baseSerialize != null)
@@ -59,6 +76,7 @@ static void GenerateSerialization(TypeDefinition td)
                     serWorker.Append(serWorker.Create(OpCodes.Ldarg_1)); // writer
                     serWorker.Append(serWorker.Create(OpCodes.Call, baseSerialize));
                 }
+            }
 
             foreach (FieldDefinition field in td.Fields)
             {
@@ -81,15 +99,18 @@ static void GenerateSerialization(TypeDefinition td)
             }
             serWorker.Append(serWorker.Create(OpCodes.Ret));
 
+            if (existingMethod == null) //only add if not just replaced body
+            {
                 td.Methods.Add(serializeFunc);
             }
+        }
 
         static void GenerateDeSerialization(TypeDefinition td)
         {
             Weaver.DLog(td, "  GenerateDeserialization");
-            foreach (MethodDefinition m in td.Methods)
+            MethodDefinition existingMethod = td.Methods.FirstOrDefault(md=>md.Name == "Deserialize");
+            if (existingMethod != null && !existingMethod.Body.IsEmptyDefault())
             {
-                if (m.Name == "Deserialize")
                 return;
             }
 
@@ -98,13 +119,22 @@ static void GenerateDeSerialization(TypeDefinition td)
                 return;
             }
 
-            MethodDefinition serializeFunc = new MethodDefinition("Deserialize",
+            MethodDefinition serializeFunc = existingMethod??new MethodDefinition("Deserialize",
                     MethodAttributes.Public | MethodAttributes.Virtual | MethodAttributes.HideBySig,
                     Weaver.voidType);
 
+            if (existingMethod == null) //only add to new method
+            {
                 serializeFunc.Parameters.Add(new ParameterDefinition("reader", ParameterAttributes.None, Weaver.CurrentAssembly.MainModule.ImportReference(Weaver.NetworkReaderType)));
+            }
             ILProcessor serWorker = serializeFunc.Body.GetILProcessor();
+            if (existingMethod != null)
+            {
+                serWorker.Body.Instructions.Clear(); //remove default nop&ret from existing empty interface method
+            }
 
+            if (!td.IsValueType) //if not struct(IMessageBase), likely same as using else {} here in all cases
+            {
                 // call base
                 MethodReference baseDeserialize = Resolvers.ResolveMethodInParents(td.BaseType, Weaver.CurrentAssembly, "Deserialize");
                 if (baseDeserialize != null)
@@ -113,6 +143,7 @@ static void GenerateDeSerialization(TypeDefinition td)
                     serWorker.Append(serWorker.Create(OpCodes.Ldarg_1)); // writer
                     serWorker.Append(serWorker.Create(OpCodes.Call, baseDeserialize));
                 }
+            }
 
             foreach (FieldDefinition field in td.Fields)
             {
@@ -135,7 +166,10 @@ static void GenerateDeSerialization(TypeDefinition td)
             }
             serWorker.Append(serWorker.Create(OpCodes.Ret));
 
+            if (existingMethod == null) //only add if not just replaced body
+            {
                 td.Methods.Add(serializeFunc);
             }
         }
+    }
 }

Assets/Mirror/Editor/Weaver/Weaver.cs

@@ -48,6 +48,7 @@ class Weaver
         public static TypeReference NetworkConnectionType;
 
         public static TypeReference MessageBaseType;
+        public static TypeReference IMessageBaseType;
         public static TypeReference SyncListType;
         public static TypeReference SyncSetType;
         public static TypeReference SyncDictionaryType;
@@ -273,6 +274,7 @@ static void SetupTargetTypes()
             NetworkConnectionType = CurrentAssembly.MainModule.ImportReference(NetworkConnectionType);
 
             MessageBaseType = NetAssembly.MainModule.GetType("Mirror.MessageBase");
+            IMessageBaseType = NetAssembly.MainModule.GetType("Mirror.IMessageBase");
             SyncListType = NetAssembly.MainModule.GetType("Mirror.SyncList`1");
             SyncSetType = NetAssembly.MainModule.GetType("Mirror.SyncSet`1");
             SyncDictionaryType = NetAssembly.MainModule.GetType("Mirror.SyncDictionary`2");
@@ -385,26 +387,10 @@ static bool CheckMessageBase(TypeDefinition td)
 
             bool didWork = false;
 
-            // are ANY parent classes MessageBase
+            if (td.ImplementsInterface(IMessageBaseType))
-            TypeReference parent = td.BaseType;
-            while (parent != null)
-            {
-                if (parent.FullName == MessageBaseType.FullName)
             {
                 MessageClassProcessor.Process(td);
                 didWork = true;
-                    break;
-                }
-                try
-                {
-                    parent = parent.Resolve().BaseType;
-                }
-                catch (AssemblyResolutionException)
-                {
-                    // this can happen for plugins.
-                    //Console.WriteLine("AssemblyResolutionException: "+ ex.ToString());
-                    break;
-                }
             }
 
             // check for embedded types

Assets/Mirror/Tests/MessageBaseTests.cs

@@ -30,6 +30,16 @@ public void Serialize(NetworkWriter writer)
         }
     }
 
+    struct WovenTestMessage: IMessageBase
+    {
+        public int IntValue;
+        public string StringValue;
+        public double DoubleValue;
+
+        public void Deserialize(NetworkReader reader) {}
+        public void Serialize(NetworkWriter writer) {}
+    }
+
     [TestFixture]
     public class MessageBaseTests
     {
@@ -47,5 +57,22 @@ public void Roundtrip()
 
             Assert.AreEqual(1, t.IntValue);
         }
+
+        [Test]
+        public void WovenSerializationBodyRoundtrip()
+        {
+            NetworkWriter w = new NetworkWriter();
+            w.Write(new WovenTestMessage{IntValue = 1, StringValue = "2", DoubleValue = 3.3});
+
+            byte[] arr = w.ToArray();
+
+            NetworkReader r = new NetworkReader(arr);
+            WovenTestMessage t = new WovenTestMessage();
+            t.Deserialize(r);
+
+            Assert.AreEqual(1, t.IntValue);
+            Assert.AreEqual("2", t.StringValue);
+            Assert.AreEqual(3.3, t.DoubleValue);
+        }
     }
 }