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.Iterator;
37: import java.util.NoSuchElementException;
38:
39: import org.codehaus.janino.util.Producer;
40:
41: /**
42: * An {@link java.util.Iterator} that iterates over all the objects produced by a delegate
43: * {@link org.codehaus.janino.util.Producer}.
44: *
45: * @see org.codehaus.janino.util.Producer
46: */
47: public class ProducerIterator implements Iterator {
48: private final Producer producer;
49:
50: private static final Object UNKNOWN = new Object();
51: private static final Object AT_END = null;
52: private Object nextElement = UNKNOWN;
53:
54: public ProducerIterator(Producer producer) {
55: this .producer = producer;
56: }
57:
58: public boolean hasNext() {
59: if (this .nextElement == UNKNOWN)
60: this .nextElement = this .producer.produce();
61: return this .nextElement != AT_END;
62: }
63:
64: public Object next() {
65: if (this .nextElement == UNKNOWN)
66: this .nextElement = this .producer.produce();
67: if (this .nextElement == AT_END)
68: throw new NoSuchElementException();
69: Object result = this .nextElement;
70: this .nextElement = UNKNOWN;
71: return result;
72: }
73:
74: public void remove() {
75: throw new UnsupportedOperationException("remove");
76: }
77: }
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