54 lines
1.8 KiB
C#
54 lines
1.8 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.Linq.Expressions;
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using System.Runtime;
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[Fx.Tag.XamlVisible(false)]
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sealed class LocationReferenceValue<T> : CodeActivity<T>, IExpressionContainer, ILocationReferenceWrapper, ILocationReferenceExpression
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{
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LocationReference locationReference;
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internal LocationReferenceValue(LocationReference locationReference)
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{
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this.UseOldFastPath = true;
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this.locationReference = locationReference;
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}
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LocationReference ILocationReferenceWrapper.LocationReference
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{
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get
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{
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return this.locationReference;
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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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// the creator of this activity is expected to have checked visibility of LocationReference.
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// we override the base CacheMetadata to avoid unnecessary reflection overhead.
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}
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protected override T Execute(CodeActivityContext context)
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{
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try
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{
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context.AllowChainedEnvironmentAccess = true;
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return context.GetValue<T>(this.locationReference);
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}
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finally
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{
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context.AllowChainedEnvironmentAccess = false;
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}
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}
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ActivityWithResult ILocationReferenceExpression.CreateNewInstance(LocationReference locationReference)
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{
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return new LocationReferenceValue<T>(locationReference);
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}
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}
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}
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