ILSpy/ICSharpCode.NRefactory.CSharp/Refactoring/LambdaHelper.cs

// 
// LambdaHelper.cs
// 
// Author:
//      Mansheng Yang <lightyang0@gmail.com>
// 
// Copyright (c) 2012 Mansheng Yang <lightyang0@gmail.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.Linq;
using ICSharpCode.NRefactory.CSharp.Resolver;
using ICSharpCode.NRefactory.TypeSystem;

namespace ICSharpCode.NRefactory.CSharp.Refactoring
{
	public class LambdaHelper
	{
		public static IType GetLambdaReturnType(RefactoringContext context, LambdaExpression lambda)
		{
			var parent = lambda.Parent;
			while (parent is ParenthesizedExpression)
				parent = parent.Parent;

			ITypeDefinition delegateTypeDef;
			if (parent is InvocationExpression) {
				var invocation = (InvocationExpression)parent;
				var argIndex = invocation.Arguments.TakeWhile (arg => !arg.Contains (lambda.StartLocation)).Count ();
				var resolveResult = (CSharpInvocationResolveResult)context.Resolve (invocation);
				delegateTypeDef = resolveResult.Arguments [argIndex].Type.GetDefinition ();
			} else {
				delegateTypeDef = context.Resolve (parent).Type.GetDefinition ();
			}
			if (delegateTypeDef == null)
				return null;
			var invokeMethod = delegateTypeDef.GetMethods (m => m.Name == "Invoke").FirstOrDefault ();
			if (invokeMethod == null)
				return null;
			return invokeMethod.ReturnType;
		}
	}
}