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Java > Open Source Codes > it > unimi > dsi > fastutil > Stack


1 package it.unimi.dsi.fastutil;
2
3 /*
4  * fastutil: Fast & compact type-specific collections for Java
5  *
6  * Copyright (C) 2002, 2003, 2004, 2005, 2006 Sebastiano Vigna
7  *
8  * This library is free software; you can redistribute it and/or
9  * modify it under the terms of the GNU Lesser General Public
10  * License as published by the Free Software Foundation; either
11  * version 2.1 of the License, or (at your option) any later version.
12  *
13  * This library is distributed in the hope that it will be useful,
14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16  * Lesser General Public License for more details.
17  *
18  * You should have received a copy of the GNU Lesser General Public
19  * License along with this library; if not, write to the Free Software
20  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
21  *
22  */
23
24 import java.util.NoSuchElementException JavaDoc;
25
26 /** A stack.
27  *
28  * <P>A stack must provide the classical {@link #push(Object)} and
29  * {@link #pop()} operations, but may be also <em>peekable</em>
30  * to some extent: it may provide just the {@link #top()} function,
31  * or even a more powerful {@link #peek(int)} method that provides
32  * access to all elements on the stack (indexed from the top, which
33  * has index 0).
34  */
35
36 public interface Stack<K> {
37
38     /** Pushes the given object on the stack.
39      *
40      * @param o the object that will become the new top of the stack.
41      */
42
43     void push( K o );
44
45     /** Pops the top off the stack.
46      *
47      * @return the top of the stack.
48      * @throws NoSuchElementException if the stack is empty.
49      */
50
51     K pop();
52
53     /** Checks whether the stack is empty.
54      *
55      * @return true if the stack is empty.
56      */
57
58     boolean isEmpty();
59
60     /** Peeks at the top of the stack (optional operation).
61      *
62      * @return the top of the stack.
63      * @throws NoSuchElementException if the stack is empty.
64      */
65
66     K top();
67
68     /** Peeks at an element on the stack (optional operation).
69      *
70      * @return the <code>i</code>-th element on the stack; 0 represents the top.
71      * @throws IndexOutOfBoundsException if the designated element does not exist..
72      */
73
74     K peek( int i );
75
76 }
77
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