LambdaValue.cs source code in C# .NET

Source code for the .NET framework in C#

                        
Code:

                         / 4.0 / 4.0 / untmp / DEVDIV_TFS / Dev10 / Releases / RTMRel / ndp / cdf / src / NetFx40 / System.Activities / System / Activities / Expressions / LambdaValue.cs / 1305376 / LambdaValue.cs
                        

                        
                            //------------------------------------------------------------------------------ 
// Copyright (c) Microsoft Corporation.  All rights reserved.
//-----------------------------------------------------------------------------

namespace System.Activities.Expressions 
{
    using System; 
    using System.Activities.ExpressionParser; 
    using System.Activities.XamlIntegration;
    using System.Collections.Generic; 
    using System.Linq.Expressions;
    using System.Runtime;
    using System.Windows.Markup;
 
    // consciously not XAML-friendly since Linq Expressions aren't create-set-use
    [Fx.Tag.XamlVisible(false)] 
    public sealed class LambdaValue : CodeActivity, IExpressionContainer, IValueSerializableExpression 
    {
        Func compiledLambdaValue; 
        Expression> lambdaValue;
        Expression> rewrittenTree;

        public LambdaValue(Expression> lambdaValue) 
        {
            Fx.Assert(lambdaValue != null, "valueExpression should not be null"); 
 
            this.lambdaValue = lambdaValue;
            this.SkipArgumentResolution = true; 
        }

        Expression IExpressionContainer.Expression
        { 
            get
            { 
                return this.lambdaValue; 
            }
        } 

        protected override void CacheMetadata(CodeActivityMetadata metadata)
        {
            // We need to rewrite the tree. 

            Expression newTree; 
            if (ExpressionUtilities.TryRewriteLambdaExpression(this.lambdaValue, out newTree, metadata)) 
            {
                this.rewrittenTree = (Expression>)newTree; 
            }
            else
            {
                this.rewrittenTree = this.lambdaValue; 
            }
        } 
 
        internal override bool TryGetValue(ActivityContext context, out TResult value)
        { 
            if (this.compiledLambdaValue == null)
            {
                this.compiledLambdaValue = this.rewrittenTree.Compile();
            } 

            value = this.compiledLambdaValue(context); 
 
            return true;
        } 

        protected override TResult Execute(CodeActivityContext context)
        {
            return ExecuteWithTryGetValue(context); 
        }
 
        public bool CanConvertToString(IValueSerializerContext context) 
        {
            return true; 
        }

        public string ConvertToString(IValueSerializerContext context)
        { 
            // This workflow contains lambda expressions specified in code.
            // These expressions are not XAML serializable. 
            // In order to make your workflow XAML-serializable, 
            // use either VisualBasicValue/Reference or ExpressionServices.Convert
            // This will convert your lambda expressions into expression activities. 
            throw FxTrace.Exception.AsError(new LambdaSerializationException());
        }
    }
} 

// File provided for Reference Use Only by Microsoft Corporation (c) 2007.

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