From 5e59e7ec86ac7d1fc438ffad21648ac900c1cc65 Mon Sep 17 00:00:00 2001
From: neuecc <ils@neue.cc>
Date: Fri, 5 Jun 2020 16:45:40 +0900
Subject: [PATCH] netstandard2.0 support  #84

---
 .../NetCore/UniTask.AsValueTask.cs            | 68 +++++++++++++++++++
 src/UniTask.NetCore/UniTask.NetCore.csproj    |  2 +-
 .../Plugins/UniTask/Runtime/IUniTaskSource.cs |  8 +--
 .../Assets/Plugins/UniTask/Runtime/UniTask.cs |  8 +++
 4 files changed, 81 insertions(+), 5 deletions(-)

diff --git a/src/UniTask.NetCore/NetCore/UniTask.AsValueTask.cs b/src/UniTask.NetCore/NetCore/UniTask.AsValueTask.cs
index 97583e7..103d129 100644
--- a/src/UniTask.NetCore/NetCore/UniTask.AsValueTask.cs
+++ b/src/UniTask.NetCore/NetCore/UniTask.AsValueTask.cs
@@ -1,6 +1,8 @@
 #pragma warning disable 0649
 
+using System;
 using System.Threading.Tasks;
+using System.Threading.Tasks.Sources;
 
 namespace Cysharp.Threading.Tasks
 {
@@ -8,12 +10,20 @@ namespace Cysharp.Threading.Tasks
     {
         public static ValueTask AsValueTask(this in UniTask task)
         {
+#if NETSTANDARD2_0
+            return new ValueTask(new UniTaskValueTaskSource(task), 0);
+#else
             return task;
+#endif
         }
 
         public static ValueTask<T> AsValueTask<T>(this in UniTask<T> task)
         {
+#if NETSTANDARD2_0
+            return new ValueTask<T>(new UniTaskValueTaskSource<T>(task), 0);
+#else
             return task;
+#endif
         }
 
         public static UniTask<T> AsUniTask<T>(this ValueTask<T> task, bool useCurrentSynchronizationContext = true)
@@ -26,5 +36,63 @@ namespace Cysharp.Threading.Tasks
         {
             return task.AsTask().AsUniTask(useCurrentSynchronizationContext);
         }
+
+#if NETSTANDARD2_0
+
+        class UniTaskValueTaskSource : IValueTaskSource
+        {
+            readonly UniTask task;
+            readonly UniTask.Awaiter awaiter;
+
+            public UniTaskValueTaskSource(UniTask task)
+            {
+                this.task = task;
+                this.awaiter = task.GetAwaiter();
+            }
+
+            public void GetResult(short token)
+            {
+                awaiter.GetResult();
+            }
+
+            public ValueTaskSourceStatus GetStatus(short token)
+            {
+                return (ValueTaskSourceStatus)task.Status;
+            }
+
+            public void OnCompleted(Action<object> continuation, object state, short token, ValueTaskSourceOnCompletedFlags flags)
+            {
+                awaiter.SourceOnCompleted(continuation, state);
+            }
+        }
+
+        class UniTaskValueTaskSource<T> : IValueTaskSource<T>
+        {
+            readonly UniTask<T> task;
+            readonly UniTask<T>.Awaiter awaiter;
+
+            public UniTaskValueTaskSource(UniTask<T> task)
+            {
+                this.task = task;
+                this.awaiter = task.GetAwaiter();
+            }
+
+            public T GetResult(short token)
+            {
+                return awaiter.GetResult();
+            }
+
+            public ValueTaskSourceStatus GetStatus(short token)
+            {
+                return (ValueTaskSourceStatus)task.Status;
+            }
+
+            public void OnCompleted(Action<object> continuation, object state, short token, ValueTaskSourceOnCompletedFlags flags)
+            {
+                awaiter.SourceOnCompleted(continuation, state);
+            }
+        }
+
+#endif
     }
 }
diff --git a/src/UniTask.NetCore/UniTask.NetCore.csproj b/src/UniTask.NetCore/UniTask.NetCore.csproj
index 0284d76..f7a7a2e 100644
--- a/src/UniTask.NetCore/UniTask.NetCore.csproj
+++ b/src/UniTask.NetCore/UniTask.NetCore.csproj
@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
     <PropertyGroup>
-        <TargetFrameworks>netcoreapp3.1;netstandard2.1</TargetFrameworks>
+        <TargetFrameworks>netcoreapp3.1;netstandard2.1;netstandard2.0</TargetFrameworks>
         <AssemblyName>UniTask</AssemblyName>
         <LangVersion>8.0</LangVersion>
         <RootNamespace>Cysharp.Threading.Tasks</RootNamespace>
diff --git a/src/UniTask/Assets/Plugins/UniTask/Runtime/IUniTaskSource.cs b/src/UniTask/Assets/Plugins/UniTask/Runtime/IUniTaskSource.cs
index 4904d14..8814781 100644
--- a/src/UniTask/Assets/Plugins/UniTask/Runtime/IUniTaskSource.cs
+++ b/src/UniTask/Assets/Plugins/UniTask/Runtime/IUniTaskSource.cs
@@ -19,7 +19,7 @@ namespace Cysharp.Threading.Tasks
 
     // similar as IValueTaskSource
     public interface IUniTaskSource
-#if !UNITY_2018_3_OR_NEWER
+#if !UNITY_2018_3_OR_NEWER && !NETSTANDARD2_0
         : System.Threading.Tasks.Sources.IValueTaskSource
 #pragma warning disable CS0108
 #endif
@@ -30,7 +30,7 @@ namespace Cysharp.Threading.Tasks
 
         UniTaskStatus UnsafeGetStatus(); // only for debug use.
 
-#if !UNITY_2018_3_OR_NEWER
+#if !UNITY_2018_3_OR_NEWER && !NETSTANDARD2_0
 #pragma warning restore CS0108
 
         System.Threading.Tasks.Sources.ValueTaskSourceStatus System.Threading.Tasks.Sources.IValueTaskSource.GetStatus(short token)
@@ -53,13 +53,13 @@ namespace Cysharp.Threading.Tasks
     }
 
     public interface IUniTaskSource<out T> : IUniTaskSource
-#if !UNITY_2018_3_OR_NEWER
+#if !UNITY_2018_3_OR_NEWER && !NETSTANDARD2_0
         , System.Threading.Tasks.Sources.IValueTaskSource<T>
 #endif
     {
         new T GetResult(short token);
 
-#if !UNITY_2018_3_OR_NEWER
+#if !UNITY_2018_3_OR_NEWER && !NETSTANDARD2_0
 
         new public UniTaskStatus GetStatus(short token)
         {
diff --git a/src/UniTask/Assets/Plugins/UniTask/Runtime/UniTask.cs b/src/UniTask/Assets/Plugins/UniTask/Runtime/UniTask.cs
index 7529b9a..26aa78a 100644
--- a/src/UniTask/Assets/Plugins/UniTask/Runtime/UniTask.cs
+++ b/src/UniTask/Assets/Plugins/UniTask/Runtime/UniTask.cs
@@ -78,7 +78,11 @@ namespace Cysharp.Threading.Tasks
                 return default;
             }
 
+#if NETSTANDARD2_0
+            return self.AsValueTask();
+#else
             return new System.Threading.Tasks.ValueTask(self.source, self.token);
+#endif
         }
 
 #endif
@@ -439,7 +443,11 @@ namespace Cysharp.Threading.Tasks
                 return new System.Threading.Tasks.ValueTask<T>(self.result);
             }
 
+#if NETSTANDARD2_0
+            return self.AsValueTask();
+#else
             return new System.Threading.Tasks.ValueTask<T>(self.source, self.token);
+#endif
         }
 
 #endif