77 lines
2.0 KiB
C#
77 lines
2.0 KiB
C#
//-----------------------------------------------------------------------------
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// Copyright (c) Microsoft Corporation. All rights reserved.
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//-----------------------------------------------------------------------------
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namespace System.Activities.Hosting
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{
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using System.Runtime;
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abstract class WorkflowInstanceExtensionProvider
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{
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protected WorkflowInstanceExtensionProvider()
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{
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}
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public Type Type
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{
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get;
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protected set;
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}
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protected bool GeneratedTypeMatchesDeclaredType
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{
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get;
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set;
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}
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public abstract object ProvideValue();
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public bool IsMatch<TTarget>(object value)
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where TTarget : class
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{
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Fx.Assert(value != null, "extension providers never return a null extension");
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if (value is TTarget)
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{
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if (this.GeneratedTypeMatchesDeclaredType)
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{
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return true;
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}
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else
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{
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return TypeHelper.AreReferenceTypesCompatible(this.Type, typeof(TTarget));
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}
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}
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else
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{
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return false;
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}
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}
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}
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class WorkflowInstanceExtensionProvider<T> : WorkflowInstanceExtensionProvider
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where T : class
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{
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Func<T> providerFunction;
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bool hasGeneratedValue;
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public WorkflowInstanceExtensionProvider(Func<T> providerFunction)
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: base()
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{
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this.providerFunction = providerFunction;
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base.Type = typeof(T);
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}
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public override object ProvideValue()
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{
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T value = this.providerFunction();
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if (!this.hasGeneratedValue)
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{
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base.GeneratedTypeMatchesDeclaredType = object.ReferenceEquals(value.GetType(), this.Type);
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this.hasGeneratedValue = true;
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}
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return value;
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}
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}
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}
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