source: branches/RemoveBackwardsCompatibility/HeuristicLab.ExtLibs/HeuristicLab.NRefactory/5.5.0/NRefactory.CSharp-5.5.0/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.Semantics;
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)
    {
      LambdaResolveResult rr = context.Resolve(lambda) as LambdaResolveResult;
      if (rr == null)
        return SpecialType.UnknownType;
      if (rr.IsAsync) {
        // Unpack Task<T>
        if (rr.ReturnType.IsKnownType(KnownTypeCode.Task))
          return context.Compilation.FindType(KnownTypeCode.Void);
        else if (rr.ReturnType.IsKnownType(KnownTypeCode.TaskOfT) && rr.ReturnType.IsParameterized)
          return rr.ReturnType.TypeArguments[0];
      }
      return rr.ReturnType;
    }
  }
}