1 files changed, 69 insertions, 0 deletions
diff --git a/main/src/core/MonoDevelop.Core/MonoDevelop.Projects/ExtensionChain.cs b/main/src/core/MonoDevelop.Core/MonoDevelop.Projects/ExtensionChain.cs
new file mode 100644
index 0000000000..9916adc7bd
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+++ b/main/src/core/MonoDevelop.Core/MonoDevelop.Projects/ExtensionChain.cs
@@ -0,0 +1,69 @@
+//
+// ExtensionChain.cs
+//
+// Author:
+//       Lluis Sanchez Gual <lluis@xamarin.com>
+//
+// Copyright (c) 2014 Xamarin, Inc (http://www.xamarin.com)
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+using System;
+using System.Collections.Generic;
+
+namespace MonoDevelop.Projects
+{
+	public class ExtensionChain
+	{
+		ChainedExtension first;
+		Dictionary<Type,ChainedExtension> chains = new Dictionary<Type, ChainedExtension> ();
+
+		public static ExtensionChain Create<T> (T[] extensions) where T:ChainedExtension
+		{
+			for (int n = extensions.Length - 2; n >= 0; n--)
+				extensions [n].Init (extensions [n + 1]);
+			return new ExtensionChain {
+				first = extensions[0]
+			};
+		}
+
+		public T GetExtension<T> () where T:ChainedExtension
+		{
+			ChainedExtension e;
+			if (!chains.TryGetValue (typeof(T), out e)) {
+				chains [typeof(T)] = e = ChainedExtension.FindNextImplementation<T> (first);
+			}
+			return (T)e;
+		}
+
+		public IEnumerable<ChainedExtension> GetAllExtensions ()
+		{
+			var e = first;
+			while (e != null) {
+				yield return e;
+				e = e.Next;
+			}
+		}
+
+		public void Dispose ()
+		{
+			first.DisposeChain ();
+		}
+	}
+}
+