VisualBasicReference.cs source code in C# .NET

                        Code:
                         / 4.0 / 4.0 / untmp / DEVDIV_TFS / Dev10 / Releases / RTMRel / ndp / cdf / src / NetFx40 / System.Activities / Microsoft / VisualBasic / Activities / VisualBasicReference.cs / 1305376 / VisualBasicReference.cs
                        
                        
                            //------------------------------------------------------------------------------ 
// Copyright (c) Microsoft Corporation.  All rights reserved.
//-----------------------------------------------------------------------------

namespace Microsoft.VisualBasic.Activities 
{
    using System; 
    using System.Activities; 
    using System.Activities.ExpressionParser;
    using System.Activities.XamlIntegration; 
    using System.Linq.Expressions;
    using System.Windows.Markup;

    public sealed class VisualBasicReference : CodeActivity>, IValueSerializableExpression, IExpressionContainer, IVisualBasicExpression 
    {
        Expression> expressionTree; 
        LocationFactory locationFactory; 

        public VisualBasicReference() 
            : base()
        {
            this.SkipArgumentResolution = true;
        } 

        public VisualBasicReference(string expressionText) 
            : this() 
        {
            this.ExpressionText = expressionText; 
        }

        public string ExpressionText
        { 
            get;
            set; 
        } 

        Expression IExpressionContainer.Expression 
        {
            get { return this.expressionTree; }
        }
 
        protected override Location Execute(CodeActivityContext context)
        { 
            if (this.expressionTree != null) 
            {
                return GetValueCore(context); 
            }
            else
            {
                return null; 
            }
        } 
 
        internal override bool TryGetValue(ActivityContext context, out Location value)
        { 
            if (!this.SkipArgumentResolution && this.RuntimeArguments.Count > 1)
            {
                // We can't fast path because we have arguments other than the result
                // and we haven't obtained inlined references 
                value = null;
                return false; 
            } 

            value = GetValueCore(context); 
            return true;
        }

        Location GetValueCore(ActivityContext context) 
        {
            if (this.locationFactory == null) 
            { 
                this.locationFactory = ExpressionUtilities.CreateLocationFactory(this.expressionTree);
            } 

            return this.locationFactory.CreateLocation(context);
        }
 
        protected override void CacheMetadata(CodeActivityMetadata metadata)
        { 
            this.expressionTree = null; 

            try 
            {
                this.expressionTree = VisualBasicHelper.Compile(this.ExpressionText, metadata);
                // inspect the expressionTree to see if it is a valid location expression(L-value)
                string extraErrorMessage = null; 
                if (!metadata.HasViolations && (this.expressionTree == null || !ExpressionUtilities.IsLocation(this.expressionTree, typeof(TResult), out extraErrorMessage)))
                { 
                    string errorMessage = SR.InvalidLValueExpression; 
                    if (extraErrorMessage != null)
                    { 
                        errorMessage += ":" + extraErrorMessage;
                    }
                    this.expressionTree = null;
                    metadata.AddValidationError(SR.CompilerErrorSpecificExpression(this.ExpressionText, errorMessage)); 
                }
            } 
            catch (SourceExpressionException e) 
            {
                metadata.AddValidationError(e.Message); 
            }
        }

        public bool CanConvertToString(IValueSerializerContext context) 
        {
            // we can always convert to a string 
            return true; 
        }
 
        public string ConvertToString(IValueSerializerContext context)
        {
            // Return our bracket-escaped text
            return "[" + this.ExpressionText + "]"; 
        }
    } 
} 

// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
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VisualBasicReference.cs source code in C# .NET

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