Cast.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 / Cast.cs / 1305376 / Cast.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.Linq.Expressions;
    using System.Runtime;
 
    public sealed class Cast : CodeActivity
    { 
        //Lock is not needed for operationFunction here. The reason is that delegates for a given Cast 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 checkedOperationFunction; 
        static Func uncheckedOperationFunction;
        bool checkedOperation = true;

        [RequiredArgument] 
        [DefaultValue(null)]
        public InArgument Operand 
        { 
            get;
            set; 
        }

        [DefaultValue(true)]
        public bool Checked 
        {
            get { return this.checkedOperation; } 
            set { this.checkedOperation = value; } 
        }
 
        protected override void CacheMetadata(CodeActivityMetadata metadata)
        {
            UnaryExpressionHelper.OnGetArguments(metadata, this.Operand);
 
            if (this.checkedOperation)
            { 
                EnsureOperationFunction(metadata, ref checkedOperationFunction, ExpressionType.ConvertChecked); 
            }
            else 
            {
                EnsureOperationFunction(metadata, ref uncheckedOperationFunction, ExpressionType.Convert);
            }
        } 

        void EnsureOperationFunction(CodeActivityMetadata metadata, 
            ref Func operationFunction, 
            ExpressionType operatorType)
        { 
            if (operationFunction == null)
            {
                ValidationError validationError;
                if (!UnaryExpressionHelper.TryGenerateLinqDelegate( 
                            operatorType,
                            out operationFunction, 
                            out validationError)) 
                {
                    metadata.AddValidationError(validationError); 
                }
            }
        }
 
        protected override TResult Execute(CodeActivityContext context)
        { 
            TOperand operandValue = this.Operand.Get(context); 

            //if user changed Checked flag between Open and Execution, 
            //a NRE may be thrown and that's by design
            if (this.checkedOperation)
            {
                return checkedOperationFunction(operandValue); 
            }
            else 
            { 
                return uncheckedOperationFunction(operandValue);
            } 
        }
    }
}

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

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