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1
19 package org.netbeans.modules.javacore;
20
21 import java.util.AbstractSequentialList  ;
22 import java.util.Iterator ;
23 import java.util.ListIterator ;
24 import java.util.NoSuchElementException ;
25
26
30 public class LazyImmutableList extends AbstractSequentialList {
31 private LazyIterator internal;
32 private boolean complete = false;
33 private final Object [] array;
34 private int nextIndex = 0;
35
36
37 public LazyImmutableList(LazyIterator internalIterator) {
38 internal = internalIterator;
39 array = new Object [internalIterator.maxEstimatedSize()];
40 }
41
42 public int size() {
43 while (internal != null) {
44 nextItem();
45 }
46 return nextIndex;
47 }
48
49 public ListIterator listIterator(int index) {
50 return new LazyImmutableIterator(index);
51 }
52
53 public int maxEstimatedSize() {
54 return internal == null ? nextIndex : internal.maxEstimatedSize();
55 }
56
57 private void nextItem() {
58 if (internal != null && internal.hasNext()) {
59 array[nextIndex] = internal.next();
60 nextIndex++;
61 } else {
62 internal = null;
63 }
64 }
65
66 private class LazyImmutableIterator implements ListIterator {
67 private int currentIndex;
68
69 public LazyImmutableIterator(int index) {
70 currentIndex = index;
71 }
72
73 public boolean hasNext() {
74 while (nextIndex <= currentIndex && internal != null) {
75 nextItem();
76 }
77 return nextIndex > currentIndex;
78 }
79
80 public int previousIndex() {
81 return currentIndex - 1;
82 }
83
84 public Object previous() {
85 if (hasPrevious()) {
86 currentIndex--;
87 return array[currentIndex];
88 }
89 throw new NoSuchElementException ();
90 }
91
92 public boolean hasPrevious() {
93 return currentIndex > 0;
94 }
95
96 public Object next() {
97 if (hasNext()) {
98 currentIndex++;
99 return array[currentIndex - 1];
100 }
101 throw new NoSuchElementException ();
102 }
103
104 public int nextIndex() {
105 return currentIndex;
106 }
107
108 public void add(Object o) {
109 throw new UnsupportedOperationException ();
110 }
111
112 public void set(Object o) {
113 throw new UnsupportedOperationException ();
114 }
115
116 public void remove() {
117 throw new UnsupportedOperationException ();
118 }
119 }
120
121 public static abstract class LazyIterator implements Iterator {
122 public final void remove() {
123 throw new UnsupportedOperationException ();
124 }
125
126 protected abstract int maxEstimatedSize();
127 }
128 }
129
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Java API By Example, From Geeks To Geeks.