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53 lines
2.1 KiB
53 lines
2.1 KiB
5 years ago
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#if NET20 || NET30 || NET35 || !NET_4_6
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using System.Diagnostics.Contracts;
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namespace System.Threading.Tasks
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{
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internal sealed class ContinuationResultTaskFromTask<TResult> : Task<TResult>, IContinuationTask
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{
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private Task _antecedent;
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public ContinuationResultTaskFromTask(Task antecedent, Delegate function, object state, TaskCreationOptions creationOptions, InternalTaskOptions internalOptions)
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: base(function, state, InternalCurrentIfAttached(creationOptions), default(CancellationToken), creationOptions, internalOptions, antecedent.ExecutingTaskScheduler)
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{
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Contract.Requires(function is Func<Task, TResult> || function is Func<Task, object, TResult>, "Invalid delegate type in ContinuationResultTaskFromTask");
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_antecedent = antecedent;
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CapturedContext = ExecutionContext.Capture();
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}
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Task IContinuationTask.Antecedent
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{
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get { return _antecedent; }
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}
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/// <summary>
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/// Evaluates the value selector of the Task which is passed in as an object and stores the result.
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/// </summary>
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internal override void InnerInvoke()
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{
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// Get and null out the antecedent. This is crucial to avoid a memory
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// leak with long chains of continuations.
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var antecedent = _antecedent;
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Contract.Assert(antecedent != null, "No antecedent was set for the ContinuationResultTaskFromTask.");
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_antecedent = null;
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// Invoke the delegate
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Contract.Assert(Action != null);
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var func = Action as Func<Task, TResult>;
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if (func != null)
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{
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InternalResult = func(antecedent);
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return;
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}
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var funcWithState = Action as Func<Task, object, TResult>;
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if (funcWithState != null)
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{
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InternalResult = funcWithState(antecedent, State);
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return;
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}
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Contract.Assert(false, "Invalid Action in ContinuationResultTaskFromTask");
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}
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}
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}
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#endif
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