01: /*
02: * Janino - An embedded Java[TM] compiler
03: *
04: * Copyright (c) 2006, Arno Unkrig
05: * All rights reserved.
06: *
07: * Redistribution and use in source and binary forms, with or without
08: * modification, are permitted provided that the following conditions
09: * are met:
10: *
11: * 1. Redistributions of source code must retain the above copyright
12: * notice, this list of conditions and the following disclaimer.
13: * 2. Redistributions in binary form must reproduce the above
14: * copyright notice, this list of conditions and the following
15: * disclaimer in the documentation and/or other materials
16: * provided with the distribution.
17: * 3. The name of the author may not be used to endorse or promote
18: * products derived from this software without specific prior
19: * written permission.
20: *
21: * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
22: * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
23: * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24: * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
25: * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26: * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
27: * GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
28: * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER
29: * IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
30: * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN
31: * IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
32: */
33:
34: package org.codehaus.janino.util.iterator;
35:
36: import java.util.*;
37:
38: /**
39: * A {@link java.util.Collection} that lazily reads its elements from an
40: * {@link java.util.Iterator}.
41: * <p>
42: * In other words, you can call {@link #iterator()} as often as you want, but the
43: * {@link IteratorCollection} will iterate over its delegate only once.
44: */
45: public class IteratorCollection extends AbstractCollection {
46: private final Iterator iterator; // The delegate.
47: private final List elements = new ArrayList(); // Lazily-filled collection of the elements delivered by the delegate.
48:
49: public IteratorCollection(Iterator iterator) {
50: this .iterator = iterator;
51: }
52:
53: public Iterator iterator() {
54: return new Iterator() {
55: private Iterator elementsIterator = IteratorCollection.this .elements
56: .iterator();
57:
58: public Object next() {
59: if (this .elementsIterator != null) {
60: if (this .elementsIterator.hasNext())
61: return this .elementsIterator.next();
62: this .elementsIterator = null;
63: }
64: Object o = IteratorCollection.this .iterator.next();
65: IteratorCollection.this .elements.add(o);
66: return o;
67: }
68:
69: public boolean hasNext() {
70: return ((this .elementsIterator != null && this .elementsIterator
71: .hasNext()) || IteratorCollection.this .iterator
72: .hasNext());
73: }
74:
75: public void remove() {
76: throw new UnsupportedOperationException();
77: }
78: };
79: }
80:
81: public int size() {
82: int size = 0;
83: for (Iterator it = this.iterator(); it.hasNext(); it.next())
84: ++size;
85: return size;
86: }
87: }
|