As.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 / As.cs / 1305376 / As.cs
                        

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

namespace System.Activities.Expressions 
{
    using System.Activities; 
    using System.Activities.Statements; 
    using System.Activities.Validation;
    using System.Collections.Generic; 
    using System.ComponentModel;
    using System.Diagnostics.CodeAnalysis;
    using System.Linq.Expressions;
    using System.Runtime; 

    [SuppressMessage(FxCop.Category.Naming, FxCop.Rule.IdentifiersShouldNotMatchKeywords, 
        Justification = "Optimizing for XAML naming. VB imperative users will [] qualify (e.g. New [As])")] 
    public sealed class As : CodeActivity
    { 
        //Lock is not needed for operationFunction here. The reason is that delegates for a given As are the same.
        //It's possible that 2 threads are assigning the operationFucntion at the same time. But it's okay because the compiled codes are the same.
        static Func operationFunction;
 
        [RequiredArgument]
        [DefaultValue(null)] 
        public InArgument Operand 
        {
            get; 
            set;
        }

        protected override void CacheMetadata(CodeActivityMetadata metadata) 
        {
            UnaryExpressionHelper.OnGetArguments(metadata, this.Operand); 
 
            if (operationFunction == null)
            { 
                ValidationError validationError;
                if (!UnaryExpressionHelper.TryGenerateLinqDelegate(ExpressionType.TypeAs, out operationFunction, out validationError))
                {
                    metadata.AddValidationError(validationError); 
                }
            } 
        } 

        protected override TResult Execute(CodeActivityContext context) 
        {
            Fx.Assert(operationFunction != null, "OperationFunction must exist.");
            TOperand operandValue = this.Operand.Get(context);
            return operationFunction(operandValue); 
        }
    } 
} 

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

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