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1 using System;
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2 using System.Threading;
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3
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4 namespace Implab.Components {
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5 public class LazyAndWeak<T> where T : class {
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6
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7 readonly Func<T> m_factory;
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8 readonly object m_lock;
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9 WeakReference m_reference;
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10
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11
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12 public LazyAndWeak(Func<T> factory, bool useLock) {
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13 Safe.ArgumentNotNull(factory, "factory");
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14 m_factory = factory;
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15 m_lock = useLock ? new object() : null;
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16 }
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17
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18 public LazyAndWeak(Func<T> factory) : this(factory, false) {
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19 }
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20
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21 public T Value {
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22 get {
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23 while (true) {
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24 var weak = m_reference;
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25 T value;
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26 if (weak != null) {
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27 value = weak.Target as T;
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28 if (value != null)
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29 return value;
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30 }
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31
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32 if (m_lock == null) {
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33 value = m_factory();
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34
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35 if (Interlocked.CompareExchange(ref m_reference, new WeakReference(value), weak) == weak)
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36 return value;
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37 } else {
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38 }
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39 }
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40 }
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41 }
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42 }
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43 }
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44
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