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
|
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.tomcat.util.digester;
import java.util.ArrayList;
import java.util.EmptyStackException;
/**
* <p>Imported copy of the <code>ArrayStack</code> class from
* Commons Collections, which was the only direct dependency from Digester.</p>
*
* <p><strong>WARNNG</strong> - This class is public solely to allow it to be
* used from subpackages of <code>org.apache.commons.digester</code>.
* It should not be considered part of the public API of Commons Digester.
* If you want to use such a class yourself, you should use the one from
* Commons Collections directly.</p>
*
* <p>An implementation of the {@link java.util.Stack} API that is based on an
* <code>ArrayList</code> instead of a <code>Vector</code>, so it is not
* synchronized to protect against multi-threaded access. The implementation
* is therefore operates faster in environments where you do not need to
* worry about multiple thread contention.</p>
*
* <p>Unlike <code>Stack</code>, <code>ArrayStack</code> accepts null entries.
* </p>
*
* @see java.util.Stack
* @since Digester 1.6 (from Commons Collections 1.0)
*/
public class ArrayStack<E> extends ArrayList<E> {
/** Ensure serialization compatibility */
private static final long serialVersionUID = 2130079159931574599L;
/**
* Constructs a new empty <code>ArrayStack</code>. The initial size
* is controlled by <code>ArrayList</code> and is currently 10.
*/
public ArrayStack() {
super();
}
/**
* Constructs a new empty <code>ArrayStack</code> with an initial size.
*
* @param initialSize the initial size to use
* @throws IllegalArgumentException if the specified initial size
* is negative
*/
public ArrayStack(int initialSize) {
super(initialSize);
}
/**
* Return <code>true</code> if this stack is currently empty.
* <p>
* This method exists for compatibility with <code>java.util.Stack</code>.
* New users of this class should use <code>isEmpty</code> instead.
*
* @return true if the stack is currently empty
*/
public boolean empty() {
return isEmpty();
}
/**
* Returns the top item off of this stack without removing it.
*
* @return the top item on the stack
* @throws EmptyStackException if the stack is empty
*/
public E peek() throws EmptyStackException {
int n = size();
if (n <= 0) {
throw new EmptyStackException();
} else {
return get(n - 1);
}
}
/**
* Returns the n'th item down (zero-relative) from the top of this
* stack without removing it.
*
* @param n the number of items down to go
* @return the n'th item on the stack, zero relative
* @throws EmptyStackException if there are not enough items on the
* stack to satisfy this request
*/
public E peek(int n) throws EmptyStackException {
int m = (size() - n) - 1;
if (m < 0) {
throw new EmptyStackException();
} else {
return get(m);
}
}
/**
* Pops the top item off of this stack and return it.
*
* @return the top item on the stack
* @throws EmptyStackException if the stack is empty
*/
public E pop() throws EmptyStackException {
int n = size();
if (n <= 0) {
throw new EmptyStackException();
} else {
return remove(n - 1);
}
}
/**
* Pushes a new item onto the top of this stack. The pushed item is also
* returned. This is equivalent to calling <code>add</code>.
*
* @param item the item to be added
* @return the item just pushed
*/
public E push(E item) {
add(item);
return item;
}
}
|
