Remove the dependency on System.ValueTuple (#63)

* Add an option to get tuple data via reflection.

* Removed non-relfection-based way of getting information about the tuples.

* Make methods static back.

* Remove the nuget dependency to System.ValueTuple

src/Ben.Demystifier/Ben.Demystifier.csproj

@@ -25,9 +25,6 @@
     <PackageReference Include="System.Reflection.Metadata">
       <Version>1.5.0</Version>
     </PackageReference>
-    <PackageReference Include="System.ValueTuple">
-      <Version>4.4.0</Version>
-    </PackageReference>
   </ItemGroup>
 
 </Project>

src/Ben.Demystifier/EnhancedStackTrace.Frames.cs

@@ -508,7 +508,8 @@ namespace System.Diagnostics
             {
                 return "out";
             }
-            else if (parameterType != null && parameterType.IsByRef)
+
+            if (parameterType != null && parameterType.IsByRef)
             {
                 var attribs = parameter.GetCustomAttributes(inherit: false);
                 if (attribs?.Length > 0)
@@ -549,17 +550,15 @@ namespace System.Diagnostics
             {
                 var customAttribs = parameter.GetCustomAttributes(inherit: false);
 
-                if ((customAttribs?.Length ?? 0) > 0)
-                {
-                    var tupleNames = customAttribs
-                        .OfType<TupleElementNamesAttribute>().FirstOrDefault()?.TransformNames;
+                var tupleNameAttribute = customAttribs.OfType<Attribute>().FirstOrDefault(a => a.IsTupleElementNameAttribue());
+
+                var tupleNames = tupleNameAttribute?.GetTransformerNames();
 
                 if (tupleNames?.Count > 0)
                 {
                     return GetValueTupleParameter(tupleNames, prefix, parameter.Name, parameterType);
                 }
             }
-            }
 
             if (parameterType.IsByRef)
             {

src/Ben.Demystifier/Internal/ReflectionHelper.cs

@@ -1,8 +1,9 @@
 // Copyright (c) Ben A Adams. All rights reserved.
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
+using System.Collections.Generic;
 using System.Reflection;
-using System.Reflection.Emit;
+using System.Threading;
 
 namespace System.Diagnostics.Internal
 {
@@ -11,6 +12,8 @@ namespace System.Diagnostics.Internal
     /// </summary>
     public static class ReflectionHelper
     {
+        private static PropertyInfo tranformerNamesLazyPropertyInfo;
+
         /// <summary>
         /// Returns true if <paramref name="type"/> is <code>System.Runtime.CompilerServices.IsReadOnlyAttribute</code>.
         /// </summary>
@@ -26,5 +29,40 @@ namespace System.Diagnostics.Internal
         {
             return type.Namespace == "System" && type.Name.Contains("ValueTuple`");
         }
+
+        /// <summary>
+        /// Returns true if the given <paramref name="attribute"/> is of type <code>TupleElementNameAttribute</code>.
+        /// </summary>
+        /// <remarks>
+        /// To avoid compile-time depencency hell with System.ValueTuple, this method uses reflection and not checks statically that 
+        /// the given <paramref name="attribute"/> is <code>TupleElementNameAttribute</code>.
+        /// </remarks>
+        public static bool IsTupleElementNameAttribue(this Attribute attribute)
+        {
+            var attributeType = attribute.GetType();
+            return attributeType.Namespace == "System.Runtime.CompilerServices" &&
+                   attributeType.Name == "TupleElementNamesAttribute";
+        }
+
+        /// <summary>
+        /// Returns 'TransformNames' property value from a given <paramref name="attribute"/>.
+        /// </summary>
+        /// <remarks>
+        /// To avoid compile-time depencency hell with System.ValueTuple, this method uses reflection 
+        /// instead of casting the attribute to a specific type.
+        /// </remarks>
+        public static IList<string> GetTransformerNames(this Attribute attribute)
+        {
+            Debug.Assert(attribute.IsTupleElementNameAttribue());
+
+            var propertyInfo = GetTransformNamesPropertyInfo(attribute.GetType());
+            return (IList<string>)propertyInfo.GetValue(attribute);
+        }
+
+        private static PropertyInfo GetTransformNamesPropertyInfo(Type attributeType)
+        {
+            return LazyInitializer.EnsureInitialized(ref tranformerNamesLazyPropertyInfo,
+                () => attributeType.GetProperty("TransformNames", BindingFlags.Instance | BindingFlags.Public));
+        }
     }
 }

test/Ben.Demystifier.Benchmarks/Exceptions.cs

@@ -1,4 +1,5 @@
 using System;
+using System.Collections.Generic;
 using System.Diagnostics;
 using BenchmarkDotNet.Attributes;
 using BenchmarkDotNet.Attributes.Jobs;
@@ -14,5 +15,26 @@ namespace Ben.Demystifier.Benchmarks
 
         [Benchmark(Description = "Demystify().ToString()")]
         public string Demystify() => new Exception().Demystify().ToString();
+
+        [Benchmark(Description = "(left, right).ToString()")]
+        public string ToStringForTupleBased() => GetException(() => ReturnsTuple()).ToString();
+
+        [Benchmark(Description = "(left, right).Demystify().ToString()")]
+        public string ToDemystifyForTupleBased() => GetException(() => ReturnsTuple()).Demystify().ToString();
+
+        private static Exception GetException(Action action)
+        {
+            try
+            {
+                action();
+                throw new InvalidOperationException("Should not be reachable.");
+            }
+            catch (Exception e)
+            {
+                return e;
+            }
+        }
+
+        private static List<(int left, int right)> ReturnsTuple() => throw new Exception();
     }
 }

test/Ben.Demystifier.Test/Ben.Demystifier.Test.csproj

@@ -7,6 +7,7 @@
   </PropertyGroup>
 
   <ItemGroup>
+    <PackageReference Include="System.ValueTuple" Version="4.4.0" />
     <PackageReference Include="xunit" Version="2.3.1" />
     <PackageReference Include="xunit.runner.visualstudio" Version="2.3.1" />
   </ItemGroup>

test/Ben.Demystifier.Test/EnhancedStackTraceTests.cs

@@ -1,7 +1,4 @@
-using System;
-using System.Collections.Generic;
 using System.Diagnostics;
-using System.Text;
 using Xunit;
 
 namespace Ben.Demystifier.Test

test/Ben.Demystifier.Test/ToDemystifiedStringTests.cs

@@ -1,7 +1,5 @@
 using System;
-using System.Collections.Generic;
 using System.Diagnostics;
-using System.Text;
 using System.Threading.Tasks;
 using Xunit;
 using Xunit.Abstractions;
@@ -22,7 +20,7 @@ namespace Ben.Demystifier.Test
         {
             try
             {
-                SimpleMethodThatThrows().Wait();
+                SimpleMethodThatThrows(null).Wait();
             }
             catch (Exception e)
             {
@@ -39,10 +37,15 @@ namespace Ben.Demystifier.Test
                 Assert.Equal(original, afterDemystified);
             }
 
-            async Task SimpleMethodThatThrows()
+            async Task SimpleMethodThatThrows(string value)
+            {
+                if (value == null)
                 {
                     throw new InvalidOperationException("message");
                 }
+
+                await Task.Yield();
+            }
         }
     }
 }