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1 using System;
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2 using System.Diagnostics;
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3
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4 namespace Implab {
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5 public class Deferred<T> : IResolvable<T> {
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6 readonly AbstractPromise<T> m_promise;
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7 readonly IDispatcher m_dispatcher;
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8
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9 internal Deferred(AbstractPromise<T> promise, IDispatcher dispatcher) {
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10 Debug.Assert(promise != null);
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11 m_promise = promise;
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12 m_dispatcher = dispatcher;
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13 }
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14
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15 public IPromise<T> Promise {
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16 get { return m_promise; }
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17 }
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18
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19 public void Reject(Exception error) {
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20 m_promise.Reject(error);
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21 }
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22
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23 public void Resolve(T value) {
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24 m_promise.Resolve(value);
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25 }
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26
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27 public void Resolve(IPromise<T> thenable) {
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28 if (thenable == null)
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29 Reject(new Exception("The promise or task are expected"));
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30 if (thenable == m_promise)
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31 Reject(new Exception("The promise cannot be resolved with oneself"));
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32
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33 else if (m_dispatcher != null)
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34 // dispatch (see ecma-262/6.0: 25.4.1.3.2 Promise Resolve Functions)
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35 m_dispatcher.Enqueue(() => Chain(thenable));
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36 else
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37 Chain(thenable);
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38 }
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39
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40 void Chain(IPromise<T> thenable) {
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41 try {
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42 thenable.Then(this);
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43 } catch (Exception err) {
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44 Reject(err);
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45 }
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46 }
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47 }
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48 } |