1 files changed, 64 insertions, 0 deletions
diff --git a/main/src/addins/CSharpBinding/Util/TypeSyntaxComparer.cs b/main/src/addins/CSharpBinding/Util/TypeSyntaxComparer.cs
new file mode 100644
index 0000000000..ec46567e7f
--- /dev/null
+++ b/main/src/addins/CSharpBinding/Util/TypeSyntaxComparer.cs
@@ -0,0 +1,64 @@
+// Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the Apache License, Version 2.0.  See License.txt in the project root for license information.
+
+using System;
+using System.Collections.Generic;
+using Microsoft.CodeAnalysis.CSharp;
+using Microsoft.CodeAnalysis.CSharp.Symbols;
+using Microsoft.CodeAnalysis.CSharp.Syntax;
+using Microsoft.CodeAnalysis.Text;
+using Microsoft.CodeAnalysis;
+
+namespace ICSharpCode.NRefactory6.CSharp
+{
+	internal class TypeSyntaxComparer : IComparer<TypeSyntax>
+	{
+		private readonly IComparer<SyntaxToken> _tokenComparer;
+		internal IComparer<NameSyntax> NameComparer;
+
+		internal TypeSyntaxComparer(IComparer<SyntaxToken> tokenComparer)
+		{
+			_tokenComparer = tokenComparer;
+		}
+
+		public int Compare(TypeSyntax x, TypeSyntax y)
+		{
+			if (x == y)
+			{
+				return 0;
+			}
+
+			x = UnwrapType(x);
+			y = UnwrapType(y);
+
+			if (x is NameSyntax && y is NameSyntax)
+			{
+				return NameComparer.Compare((NameSyntax)x, (NameSyntax)y);
+			}
+
+			// we have two predefined types, or a predefined type and a normal C# name.  We only need
+			// to compare the first tokens here.
+			return _tokenComparer.Compare(x.GetFirstToken(includeSkipped: true), y.GetFirstToken());
+		}
+
+		private TypeSyntax UnwrapType(TypeSyntax type)
+		{
+			while (true)
+			{
+				switch (type.Kind())
+				{
+				case SyntaxKind.ArrayType:
+					type = ((ArrayTypeSyntax)type).ElementType;
+					break;
+				case SyntaxKind.PointerType:
+					type = ((PointerTypeSyntax)type).ElementType;
+					break;
+				case SyntaxKind.NullableType:
+					type = ((NullableTypeSyntax)type).ElementType;
+					break;
+				default:
+					return type;
+				}
+			}
+		}
+	}
+}