Add codegen support for binding Task and Task<T> return values

Rohansi · Jun 6, 2024 · 4fdd5f8 · 4fdd5f8
1 parent e57026b
commit 4fdd5f8
Show file tree

Hide file tree

Showing 4 changed files with 45 additions and 0 deletions.
diff --git a/Mond.SourceGenerator/MondSourceGenerator.cs b/Mond.SourceGenerator/MondSourceGenerator.cs
@@ -217,6 +217,18 @@ private static string ConvertToMondValue(GeneratorExecutionContext context, stri
                     return $"({input} ?? MondValue.Undefined)";
                 }
 
+                if (SymbolEqualityComparer.Default.Equals(type, TypeLookup.Task))
+                {
+                    return $"Mond.Libraries.AsyncUtil.ToObject({input});";
+                }
+
+                if (type is INamedTypeSymbol { Arity: 1 } namedType && SymbolEqualityComparer.Default.Equals(namedType.ConstructedFrom, TypeLookup.TaskOfT))
+                {
+                    var returnType = namedType.TypeArguments[0];
+                    var returnWrapper = ConvertToMondValue(context, "t.Result", returnType, typeSource);
+                    return $"Mond.Libraries.AsyncUtil.ToObject({input}.ContinueWith(t => t.IsFaulted ? AsyncUtil.RethrowAsyncException(t.Exception) : {returnWrapper}));";
+                }
+
                 if (type.HasAttribute("MondClassAttribute"))
                 {
                     return $"MondValue.ClassInstance(state, {input}, \"{type.GetFullyQualifiedName()}\")";

diff --git a/Mond.SourceGenerator/TypeLookup.cs b/Mond.SourceGenerator/TypeLookup.cs
@@ -9,6 +9,8 @@ internal static class TypeLookup
     public static INamedTypeSymbol Void { get; private set; }
     public static INamedTypeSymbol String { get; private set; }
     public static INamedTypeSymbol Bool { get; private set; }
+    public static INamedTypeSymbol Task { get; private set; }
+    public static INamedTypeSymbol TaskOfT { get; private set; }
     public static INamedTypeSymbol MondValue { get; private set; }
     public static INamedTypeSymbol MondValueNullable { get; private set; }
     public static IArrayTypeSymbol MondValueArray { get; private set; }
@@ -34,6 +36,8 @@ public static bool Initialize(GeneratorExecutionContext context)
         var stringSym = compilation.GetSpecialType(SpecialType.System_String);
         var boolSym = compilation.GetSpecialType(SpecialType.System_Boolean);
         var nullableSym = compilation.GetSpecialType(SpecialType.System_Nullable_T);
+        var taskSym = compilation.GetTypeByMetadataName("System.Threading.Tasks.Task");
+        var taskOfTSym = compilation.GetTypeByMetadataName("System.Threading.Tasks.Task`1");
 
         var mondValueSym = compilation.GetTypesByMetadataName("Mond.MondValue")
             .SingleOrDefault(s => s.ContainingAssembly.Identity.Name == "Mond");
@@ -56,6 +60,8 @@ public static bool Initialize(GeneratorExecutionContext context)
         Void = voidSym;
         String = stringSym;
         Bool = boolSym;
+        Task = taskSym;
+        TaskOfT = taskOfTSym;
         MondValue = mondValueSym;
         MondValueNullable = nullableSym.Construct(mondValueSym);
         MondValueArray = compilation.CreateArrayTypeSymbol(mondValueSym);

diff --git a/Mond.Tests/Binding/FunctionTests.cs b/Mond.Tests/Binding/FunctionTests.cs
@@ -1,5 +1,6 @@
 using System.Collections.Generic;
 using System.Linq;
+using System.Threading.Tasks;
 using Mond.Binding;
 using NUnit.Framework;
 
@@ -320,6 +321,19 @@ public static string Greet(ClassTests.Person person)
             return person.GenerateGreeting();
         }
 
+        [MondFunction]
+        public static async Task AsyncMethod(int ms)
+        {
+            await Task.Delay(ms);
+        }
+
+        [MondFunction]
+        public static async Task<int> AsyncMethodWithReturn(int ms)
+        {
+            await Task.Delay(ms);
+            return ms;
+        }
+
 #if false
         [MondFunction]
         public static decimal UnsupportedReturn()

diff --git a/Mond/Libraries/AsyncLibraries.cs b/Mond/Libraries/AsyncLibraries.cs
@@ -1,8 +1,10 @@
 using System;
 using System.Collections.Generic;
+using System.ComponentModel;
 using System.Linq;
 using System.Threading;
 using System.Threading.Tasks;
+using JetBrains.Annotations;
 using Mond.Libraries.Async;
 
 namespace Mond.Libraries
@@ -137,5 +139,16 @@ public static Task<MondValue>[] ToTaskArray(MondState state, params MondValue[]
 
             return token.CancellationToken;
         }
+
+        /// <summary>
+        /// Used to rethrow exceptions thrown in async methods that have bindings generated for them.
+        /// </summary>
+        [EditorBrowsable(EditorBrowsableState.Never), UsedImplicitly]
+        public static MondValue RethrowAsyncException(AggregateException e)
+        {
+            var exception = e.InnerExceptions.Count != 1 ? e : e.InnerException ?? e;
+            System.Runtime.ExceptionServices.ExceptionDispatchInfo.Capture(exception).Throw();
+            throw exception;
+        }
     }
 }