blob: d13d36e25ba31d0ea1bafaa8b92566c1d8d6c3f3 (
plain) (
blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
|
/*******************************************************************************
* Copyright (c) 2008 Oracle. All rights reserved.
* This program and the accompanying materials are made available under the
* terms of the Eclipse Public License v1.0, which accompanies this distribution
* and is available at http://www.eclipse.org/legal/epl-v10.html.
*
* Contributors:
* Oracle - initial API and implementation
******************************************************************************/
package org.eclipse.jpt.utility.internal.iterators;
import java.util.List;
import java.util.ListIterator;
import java.util.NoSuchElementException;
import org.eclipse.jpt.utility.internal.StringTools;
/**
* A <code>ReadOnlyCompositeListIterator</code> wraps a list
* of <code>ListIterator</code>s and makes them appear to be a single
* read-only <code>ListIterator</code>. A read-only composite list
* iterator is more flexible than a normal composite when it comes to the element types of
* the nested iterators.
*/
public class ReadOnlyCompositeListIterator<E>
implements ListIterator<E>
{
private final ListIterator<? extends ListIterator<? extends E>> iterators;
private ListIterator<? extends E> nextIterator;
private int nextIndex;
/**
* Construct a read-only list iterator with the specified list of
* list iterators.
*/
public ReadOnlyCompositeListIterator(List<? extends ListIterator<? extends E>> iterators) {
this(iterators.listIterator());
}
/**
* Construct a read-only list iterator with the specified list of
* list iterators.
*/
public ReadOnlyCompositeListIterator(ListIterator<? extends ListIterator<? extends E>> iterators) {
super();
this.iterators = iterators;
this.nextIndex = 0;
}
/**
* Construct a read-only list iterator with the specified object prepended
* to the specified iterator.
*/
@SuppressWarnings("unchecked")
public ReadOnlyCompositeListIterator(E object, ListIterator<? extends E> iterator) {
this(new SingleElementListIterator<E>(object), iterator);
}
/**
* Construct a read-only list iterator with the specified object appended
* to the specified iterator.
*/
@SuppressWarnings("unchecked")
public ReadOnlyCompositeListIterator(ListIterator<? extends E> iterator, E object) {
this(iterator, new SingleElementListIterator<E>(object));
}
/**
* Construct a read-only list iterator with the specified list iterators.
*/
public ReadOnlyCompositeListIterator(ListIterator<? extends E>... iterators) {
this(new ArrayListIterator<ListIterator<? extends E>>(iterators));
}
public boolean hasNext() {
try {
this.loadNextIterator();
} catch (NoSuchElementException ex) {
// this occurs if there are no iterators at all
return false;
}
return this.nextIterator.hasNext();
}
public boolean hasPrevious() {
try {
this.loadPreviousIterator();
} catch (NoSuchElementException ex) {
// this occurs if there are no iterators at all
return false;
}
return this.nextIterator.hasPrevious();
}
public E next() {
this.loadNextIterator();
E result = this.nextIterator.next();
// the statement above will throw a NoSuchElementException
// if the current iterator is at the end of the line;
// so if we get here, we can increment 'nextIndex'
this.nextIndex++;
return result;
}
public int nextIndex() {
return this.nextIndex;
}
public E previous() {
this.loadPreviousIterator();
E result = this.nextIterator.previous();
// the statement above will throw a NoSuchElementException
// if the current iterator is at the end of the line;
// so if we get here, we can decrement 'nextIndex'
this.nextIndex--;
return result;
}
public int previousIndex() {
return this.nextIndex - 1;
}
public void add(E o) {
// the list iterator is read-only
throw new UnsupportedOperationException();
}
public void remove() {
// the list iterator is read-only
throw new UnsupportedOperationException();
}
public void set(E e) {
// the list iterator is read-only
throw new UnsupportedOperationException();
}
/**
* Load nextIterator with the first iterator that <code>hasNext()</code>
* or the final iterator if all the elements have already been retrieved.
*/
private void loadNextIterator() {
this.checkNextIterator();
while (( ! this.nextIterator.hasNext()) && this.iterators.hasNext()) {
this.nextIterator = this.iterators.next();
}
}
/**
* Load nextIterator with the first iterator that <code>hasPrevious()</code>
* or the first iterator if all the elements have already been retrieved.
*/
private void loadPreviousIterator() {
this.checkNextIterator();
while (( ! this.nextIterator.hasPrevious()) && this.iterators.hasPrevious()) {
this.nextIterator = this.iterators.previous();
}
}
/**
* If 'nextIterator' is null, load it with the first iterator.
*/
private void checkNextIterator() {
if (this.nextIterator == null) {
this.nextIterator = this.iterators.next();
}
}
@Override
public String toString() {
return StringTools.buildToStringFor(this, this.iterators);
}
}
|
