1 package org.apache.velocity.util;
2
3 /*
4 * Licensed to the Apache Software Foundation (ASF) under one
5 * or more contributor license agreements. See the NOTICE file
6 * distributed with this work for additional information
7 * regarding copyright ownership. The ASF licenses this file
8 * to you under the Apache License, Version 2.0 (the
9 * "License"); you may not use this file except in compliance
10 * with the License. You may obtain a copy of the License at
11 *
12 * http://www.apache.org/licenses/LICENSE-2.0
13 *
14 * Unless required by applicable law or agreed to in writing,
15 * software distributed under the License is distributed on an
16 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
17 * KIND, either express or implied. See the License for the
18 * specific language governing permissions and limitations
19 * under the License.
20 */
21
22 import java.util.Iterator;
23 import java.util.NoSuchElementException;
24 import java.lang.reflect.Array;
25
26
27 /**
28 * <p>
29 * An Iterator wrapper for an Object[]. This will
30 * allow us to deal with all array like structures
31 * in a consistent manner.
32 * </p>
33 * <p>
34 * WARNING : this class's operations are NOT synchronized.
35 * It is meant to be used in a single thread, newly created
36 * for each use in the #foreach() directive.
37 * If this is used or shared, synchronize in the
38 * next() method.
39 * </p>
40 *
41 * @author <a href="mailto:jvanzyl@apache.org">Jason van Zyl</a>
42 * @author <a href="mailto:geirm@apache.org">Geir Magnusson Jr.</a>
43 * @version $Id: ArrayIterator.java 463298 2006-10-12 16:10:32Z henning $
44 */
45 public class ArrayIterator implements Iterator
46 {
47 /**
48 * The objects to iterate.
49 */
50 private Object array;
51
52 /**
53 * The current position and size in the array.
54 */
55 private int pos;
56 private int size;
57
58 /**
59 * Creates a new iterator instance for the specified array.
60 *
61 * @param array The array for which an iterator is desired.
62 */
63 public ArrayIterator(Object array)
64 {
65 /*
66 * if this isn't an array, then throw. Note that this is
67 * for internal use - so this should never happen - if it does
68 * we screwed up.
69 */
70
71 if ( !array.getClass().isArray() )
72 {
73 throw new IllegalArgumentException(
74 "Programmer error : internal ArrayIterator invoked w/o array");
75 }
76
77 this.array = array;
78 pos = 0;
79 size = Array.getLength( this.array );
80 }
81
82 /**
83 * Move to next element in the array.
84 *
85 * @return The next object in the array.
86 */
87 public Object next()
88 {
89 if (pos < size )
90 return Array.get( array, pos++);
91
92 /*
93 * we screwed up...
94 */
95
96 throw new NoSuchElementException("No more elements: " + pos +
97 " / " + size);
98 }
99
100 /**
101 * Check to see if there is another element in the array.
102 *
103 * @return Whether there is another element.
104 */
105 public boolean hasNext()
106 {
107 return (pos < size );
108 }
109
110 /**
111 * No op--merely added to satify the <code>Iterator</code> interface.
112 */
113 public void remove()
114 {
115 throw new UnsupportedOperationException();
116 }
117 }