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: * An {@link java.util.Iterator} that iterates over a delegate, and while
40: * it encounters an array, a {@link java.util.Collection}, an
41: * {@link java.util.Enumeration} or a {@link java.util.Iterator} element, it iterates
42: * into it recursively.
43: * <p>
44: * Be aware that {@link #hasNext()} must read ahead one element.
45: */
46: public class TraversingIterator implements Iterator {
47: private final Stack nest = new Stack(); // Iterator
48: private Object nextElement = null;
49: private boolean nextElementRead = false; // Have we read ahead?
50:
51: public TraversingIterator(Iterator delegate) {
52: this .nest.push(delegate);
53: }
54:
55: public boolean hasNext() {
56: return this .nextElementRead || this .readNext();
57: }
58:
59: public Object next() {
60: if (!this .nextElementRead && !this .readNext())
61: throw new NoSuchElementException();
62: this .nextElementRead = false;
63: return this .nextElement;
64: }
65:
66: /**
67: * Reads the next element and stores it in {@link #nextElement}.
68: * @return <code>false</code> if no more element can be read.
69: */
70: private boolean readNext() {
71: while (!this .nest.empty()) {
72: Iterator it = (Iterator) this .nest.peek();
73: if (!it.hasNext()) {
74: this .nest.pop();
75: continue;
76: }
77: Object o = it.next();
78: if (o instanceof Iterator) {
79: this .nest.push(o);
80: } else if (o instanceof Object[]) {
81: this .nest.push(Arrays.asList((Object[]) o).iterator());
82: } else if (o instanceof Collection) {
83: this .nest.push(((Collection) o).iterator());
84: } else if (o instanceof Enumeration) {
85: this .nest
86: .push(new EnumerationIterator((Enumeration) o));
87: } else {
88: this .nextElement = o;
89: this .nextElementRead = true;
90: return true;
91: }
92: }
93: return false;
94: }
95:
96: public void remove() {
97: throw new UnsupportedOperationException("remove");
98: }
99: }
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