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1 package jp.ac.u_ryukyu.ie.cr.shoshi.jungle.traverser;
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2
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3 import java.util.Iterator;
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26
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4
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5 import jp.ac.u_ryukyu.ie.cr.shoshi.jungle.util.DefaultEither;
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6 import jp.ac.u_ryukyu.ie.cr.shoshi.jungle.util.Either;
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7 import jp.ac.u_ryukyu.ie.cr.shoshi.jungle.util.Error;
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10
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8 import fj.data.List;
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9
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10 public class DefaultTraverser<T extends Parent<T>> implements Traverser<T>
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10
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11 {
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12 @Override
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13 public Either<Error,Traversal<T>> traverse(final T _root,Evaluator<T> _evaluator)
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10
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14 {
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15 Children<T> wrapper = new Children<T>(){
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16 @Override
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17 public Iterator<T> iterator(){
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18 List<T> list = List.nil();
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19 return list.cons(_root).iterator();
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20 }
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23
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21 @Override
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22 public int size(){
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23 return 1;
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24 }
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25 };
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26
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27 Either<Error,List<T>> ret = _traverse(wrapper,_evaluator);
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28 if(ret.isA()){
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29 return DefaultEither.newA(ret.a());
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30 }
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31
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32 final Iterable<T> iterable = ret.b();
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33 final T destination = ret.b().last();
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34
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35 Traversal<T> traversal = new Traversal<T>(){
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36 @Override
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37 public Iterator<T> iterator(){
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38 return iterable.iterator();
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39 }
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23
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40
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41 @Override
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42 public T destination(){
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43 return destination;
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23
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44 }
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45 };
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46
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47 return DefaultEither.newB(traversal);
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48 }
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49
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50 private Either<Error,List<T>> _traverse(Children<T> _chs,Evaluator<T> _evaluator)
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51 {
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52 int pos = 0;
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53 for(T ch : _chs){
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54 Evaluation<T> e = _evaluator.evaluate(ch,pos);
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55 Result r = e.result();
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56 if(r == Result.ACCEPT){
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57 return _accept(ch,e.evaluator());
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58 }
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59
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60 if(r == Result.BREAK){
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61 break;
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62 }
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63
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64 if(r == Result.CONTINUE){
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65 continue;
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66 }
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67
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68 return DefaultEither.newA(TraverserError.UNDEFINED_OPERATOR);
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69 }
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70
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71 List<T> empty = List.nil();
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72 Either<Error,List<T>> ret = DefaultEither.newB(empty);
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73 return ret;
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74 }
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75
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76 private Either<Error,List<T>> _accept(T _current,Evaluator<T> _evaluator)
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77 {
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78 Children<T> chs = _current.children();
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79 Either<Error,List<T>> either = _traverse(chs,_evaluator);
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80 if(either.isA()){
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81 return either;
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82 }
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83
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84 List<T> list = either.b();
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85 List<T> newList = list.cons(_current);
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86 return DefaultEither.newB(newList);
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87 }
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88 }
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