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1
29 package net.metanotion.util.skiplist;
30
31 import java.util.ListIterator  ;
32 import java.util.NoSuchElementException ;
33
34
39 public class SkipIterator implements ListIterator {
40 SkipSpan ss;
41 int index;
42
43 protected SkipIterator() { }
44 public SkipIterator(SkipSpan ss, int index) {
45 if(ss==null) { throw new NullPointerException (); }
46 this.ss = ss;
47 this.index = index;
48 }
49
50 public boolean hasNext() {
51 if(index < ss.nKeys) { return true; }
52 return false;
53 }
54
55 public Object next() {
56 Object o;
57 if(index < ss.nKeys) {
58 o = ss.vals[index];
59 } else {
60 throw new NoSuchElementException ();
61 }
62
63 if(index < (ss.nKeys-1)) {
64 index++;
65 } else if(ss.next != null) {
66 ss = ss.next;
67 index = 0;
68 } else {
69 index = ss.nKeys;
70 }
71 return o;
72 }
73
74 public Comparable nextKey() {
75 Comparable c;
76 if(index < ss.nKeys) { return ss.keys[index]; }
77 throw new NoSuchElementException ();
78 }
79
80 public boolean hasPrevious() {
81 if(index > 0) { return true; }
82 if((ss.prev != null) && (ss.prev.nKeys > 0)) { return true; }
83 return false;
84 }
85
86 public Object previous() {
87 if(index > 0) {
88 index--;
89 } else if(ss.prev != null) {
90 ss = ss.prev;
91 if(ss.nKeys <= 0) { throw new NoSuchElementException (); }
92 index = (ss.nKeys - 1);
93 }
94 return ss.vals[index];
95 }
96
97
98 public void add(Object o) { throw new UnsupportedOperationException (); }
100 public void remove() { throw new UnsupportedOperationException (); }
101 public void set(Object o) { throw new UnsupportedOperationException (); }
102 public int nextIndex() { throw new UnsupportedOperationException (); }
103 public int previousIndex() { throw new UnsupportedOperationException (); }
104
105 }
106 |
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