85 lines
3.1 KiB
C#
85 lines
3.1 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 LambdaValue<TResult> : CodeActivity<TResult>, IExpressionContainer, IValueSerializableExpression
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{
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Func<ActivityContext, TResult> compiledLambdaValue;
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Expression<Func<ActivityContext, TResult>> lambdaValue;
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Expression<Func<ActivityContext, TResult>> rewrittenTree;
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public LambdaValue(Expression<Func<ActivityContext, TResult>> lambdaValue)
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{
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if (lambdaValue == null)
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{
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throw FxTrace.Exception.ArgumentNull("lambdaValue");
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}
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this.lambdaValue = lambdaValue;
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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.lambdaValue;
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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.lambdaValue, out newTree, publicAccessor))
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{
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this.rewrittenTree = (Expression<Func<ActivityContext, TResult>>)newTree;
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}
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else
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{
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this.rewrittenTree = this.lambdaValue;
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}
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}
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protected override TResult Execute(CodeActivityContext context)
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{
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if (this.compiledLambdaValue == null)
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{
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this.compiledLambdaValue = this.rewrittenTree.Compile();
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}
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return this.compiledLambdaValue(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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