97 lines
3.7 KiB
C#
97 lines
3.7 KiB
C#
//-----------------------------------------------------------------------------
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// Copyright (c) Microsoft Corporation. All rights reserved.
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//-----------------------------------------------------------------------------
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namespace System.Activities.Expressions
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{
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using System;
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using System.Activities.ExpressionParser;
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using System.Activities.XamlIntegration;
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using System.Collections.Generic;
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using System.Diagnostics;
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using System.Linq.Expressions;
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using System.Runtime;
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using System.Windows.Markup;
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// consciously not XAML-friendly since Linq Expressions aren't create-set-use
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[Fx.Tag.XamlVisible(false)]
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[DebuggerStepThrough]
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public sealed class LambdaReference<T> : CodeActivity<Location<T>>, IExpressionContainer, IValueSerializableExpression
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{
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Expression<Func<ActivityContext, T>> locationExpression;
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Expression<Func<ActivityContext, T>> rewrittenTree;
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LocationFactory<T> locationFactory;
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public LambdaReference(Expression<Func<ActivityContext, T>> locationExpression)
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{
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if (locationExpression == null)
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{
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throw FxTrace.Exception.ArgumentNull("locationExpression");
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}
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this.locationExpression = locationExpression;
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this.UseOldFastPath = true;
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}
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// this is called via reflection from Microsoft.CDF.Test.ExpressionUtilities.Activities.ActivityUtilities.ReplaceLambdaValuesInActivityTree
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internal Expression LambdaExpression
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{
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get
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{
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return this.locationExpression;
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}
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}
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protected override void CacheMetadata(CodeActivityMetadata metadata)
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{
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CodeActivityPublicEnvironmentAccessor publicAccessor = CodeActivityPublicEnvironmentAccessor.Create(metadata);
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// We need to rewrite the tree.
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Expression newTree;
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if (ExpressionUtilities.TryRewriteLambdaExpression(this.locationExpression, out newTree, publicAccessor, true))
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{
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this.rewrittenTree = (Expression<Func<ActivityContext, T>>)newTree;
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}
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else
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{
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this.rewrittenTree = this.locationExpression;
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}
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// inspect the expressionTree to see if it is a valid location expression(L-value)
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string extraErrorMessage = null;
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if (!ExpressionUtilities.IsLocation(this.rewrittenTree, typeof(T), out extraErrorMessage))
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{
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string errorMessage = SR.InvalidLValueExpression;
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if (extraErrorMessage != null)
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{
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errorMessage += ":" + extraErrorMessage;
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}
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metadata.AddValidationError(errorMessage);
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}
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}
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protected override Location<T> Execute(CodeActivityContext context)
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{
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if (this.locationFactory == null)
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{
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this.locationFactory = ExpressionUtilities.CreateLocationFactory<T>(this.rewrittenTree);
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}
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return this.locationFactory.CreateLocation(context);
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}
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public bool CanConvertToString(IValueSerializerContext context)
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{
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return true;
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}
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public string ConvertToString(IValueSerializerContext context)
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{
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// This workflow contains lambda expressions specified in code.
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// These expressions are not XAML serializable.
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// In order to make your workflow XAML-serializable,
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// use either VisualBasicValue/Reference or ExpressionServices.Convert
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// This will convert your lambda expressions into expression activities.
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throw FxTrace.Exception.AsError(new LambdaSerializationException());
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}
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}
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}
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