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)
@@ -549,15 +550,13 @@ 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());
 
-                    if (tupleNames?.Count > 0)
-                    {
-                        return GetValueTupleParameter(tupleNames, prefix, parameter.Name, parameterType);
-                    }
+                var tupleNames = tupleNameAttribute?.GetTransformerNames();
+
+                if (tupleNames?.Count > 0)
+                {
+                    return GetValueTupleParameter(tupleNames, prefix, parameter.Name, parameterType);
                 }
             }
 

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));
+        }
     }
 }