SharpDevelop/src/Libraries/NRefactory/ICSharpCode.NRefactory.CSharp.Refactoring/CodeActions/ConvertMethodGroupToLambdaAction.cs

//
// ConvertMethodGroupToLambdaAction.cs
//
// Author:
//       Mike Krüger <mkrueger@xamarin.com>
//
// Copyright (c) 2013 Xamarin Inc. (http://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 ICSharpCode.NRefactory.CSharp.Resolver;
using System.Collections.Generic;
using ICSharpCode.NRefactory.TypeSystem;
using System.Linq;

namespace ICSharpCode.NRefactory.CSharp.Refactoring
{
	[ContextAction("Convert method group to lambda expression",
	               Description = "Convert method group to lambda expression")]
	public class ConvertMethodGroupToLambdaAction : CodeActionProvider
	{
		public override IEnumerable<CodeAction> GetActions(RefactoringContext context)
		{
			Expression node = context.GetNode<IdentifierExpression>();
			if (node == null) {
				var mr = context.GetNode<MemberReferenceExpression>();
				if (mr == null || !mr.MemberNameToken.IsInside(context.Location))
					yield break;
				node = mr;
			}
			if (node == null)
				yield break;
			var rr = context.Resolve(node) as MethodGroupResolveResult;
			if (rr == null || rr.IsError)
				yield break;
			var type = TypeGuessing.GetValidTypes(context.Resolver, node).FirstOrDefault(t => t.Kind == TypeKind.Delegate);
			if (type == null)
				yield break;
			var invocationMethod = type.GetDelegateInvokeMethod();
			if (invocationMethod == null)
				yield break;

			yield return new CodeAction(
				context.TranslateString("Convert to lambda expression"), 
				script => {
					var invocation = new InvocationExpression(node.Clone(), invocationMethod.Parameters.Select(p => new IdentifierExpression(context.GetNameProposal(p.Name))));
					var lambda = new LambdaExpression {
						Body = invocation
					};
					lambda.Parameters.AddRange(
						invocation.Arguments
							.Cast<IdentifierExpression>()
							.Select(p => new ParameterDeclaration { Name = p.Identifier })
					);
					script.Replace(node, lambda);
				},
				node
			);
		}
	}
}