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1 /**
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2 * Copyright (c) Rich Hickey. All rights reserved.
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3 * The use and distribution terms for this software are covered by the
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4 * Eclipse Public License 1.0 (http://opensource.org/licenses/eclipse-1.0.php)
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5 * which can be found in the file epl-v10.html at the root of this distribution.
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6 * By using this software in any fashion, you are agreeing to be bound by
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7 * the terms of this license.
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8 * You must not remove this notice, or any other, from this software.
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9 **/
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10
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11 /* rich Jan 1, 2009 */
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12
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13 package clojure.lang;
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14
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15 import java.util.concurrent.atomic.AtomicReference;
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16
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17 final public class Atom extends ARef{
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18 final AtomicReference state;
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19
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20 public Atom(Object state){
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21 this.state = new AtomicReference(state);
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22 }
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23
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24 public Atom(Object state, IPersistentMap meta){
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25 super(meta);
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26 this.state = new AtomicReference(state);
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27 }
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28
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29 public Object deref(){
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30 return state.get();
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31 }
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32
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33 public Object swap(IFn f) throws Exception{
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34 for(; ;)
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35 {
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36 Object v = deref();
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37 Object newv = f.invoke(v);
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38 validate(newv);
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39 if(state.compareAndSet(v, newv))
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40 {
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41 notifyWatches(v, newv);
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42 return newv;
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43 }
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44 }
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45 }
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46
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47 public Object swap(IFn f, Object arg) throws Exception{
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48 for(; ;)
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49 {
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50 Object v = deref();
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51 Object newv = f.invoke(v, arg);
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52 validate(newv);
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53 if(state.compareAndSet(v, newv))
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54 {
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55 notifyWatches(v, newv);
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56 return newv;
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57 }
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58 }
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59 }
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60
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61 public Object swap(IFn f, Object arg1, Object arg2) throws Exception{
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62 for(; ;)
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63 {
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64 Object v = deref();
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65 Object newv = f.invoke(v, arg1, arg2);
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66 validate(newv);
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67 if(state.compareAndSet(v, newv))
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68 {
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69 notifyWatches(v, newv);
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70 return newv;
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71 }
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72 }
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73 }
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74
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75 public Object swap(IFn f, Object x, Object y, ISeq args) throws Exception{
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76 for(; ;)
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77 {
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78 Object v = deref();
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79 Object newv = f.applyTo(RT.listStar(v, x, y, args));
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80 validate(newv);
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81 if(state.compareAndSet(v, newv))
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82 {
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83 notifyWatches(v, newv);
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84 return newv;
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85 }
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86 }
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87 }
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88
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89 public boolean compareAndSet(Object oldv, Object newv){
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90 validate(newv);
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91 boolean ret = state.compareAndSet(oldv, newv);
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92 if(ret)
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93 notifyWatches(oldv, newv);
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94 return ret;
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95 }
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96
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97 public Object reset(Object newval){
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98 Object oldval = state.get();
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99 validate(newval);
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100 state.set(newval);
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101 notifyWatches(oldval, newval);
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102 return newval;
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103 }
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104 }
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