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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 package clojure.lang;
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12
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13 import java.io.IOException;
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14 import java.io.NotSerializableException;
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15 import java.util.Iterator;
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16
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17 public class IteratorSeq extends ASeq{
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18 final Iterator iter;
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19 final State state;
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20
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21 static class State{
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22 volatile Object val;
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23 volatile Object _rest;
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24 }
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25
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26 public static IteratorSeq create(Iterator iter){
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27 if(iter.hasNext())
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28 return new IteratorSeq(iter);
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29 return null;
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30 }
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31
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32 IteratorSeq(Iterator iter){
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33 this.iter = iter;
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34 state = new State();
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35 this.state.val = state;
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36 this.state._rest = state;
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37 }
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38
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39 IteratorSeq(IPersistentMap meta, Iterator iter, State state){
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40 super(meta);
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41 this.iter = iter;
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42 this.state = state;
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43 }
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44
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45 public Object first(){
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46 if(state.val == state)
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47 synchronized(state)
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48 {
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49 if(state.val == state)
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50 state.val = iter.next();
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51 }
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52 return state.val;
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53 }
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54
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55 public ISeq next(){
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56 if(state._rest == state)
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57 synchronized(state)
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58 {
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59 if(state._rest == state)
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60 {
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61 first();
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62 state._rest = create(iter);
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63 }
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64 }
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65 return (ISeq) state._rest;
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66 }
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67
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68 public IteratorSeq withMeta(IPersistentMap meta){
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69 return new IteratorSeq(meta, iter, state);
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70 }
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71
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72 private void writeObject (java.io.ObjectOutputStream out) throws IOException {
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73 throw new NotSerializableException(getClass().getName());
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74 }
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75 }
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