1/*
2 * Copyright (c) 2010, 2013, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.  Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26package jdk.nashorn.internal;
27
28/**
29 * Small helper class for fast int deques
30 */
31public class IntDeque {
32    private int[] deque = new int[16];
33    private int nextFree = 0;
34
35    /**
36     * Push an int value
37     * @param value value
38     */
39    public void push(final int value) {
40        if (nextFree == deque.length) {
41            final int[] newDeque = new int[nextFree * 2];
42            System.arraycopy(deque, 0, newDeque, 0, nextFree);
43            deque = newDeque;
44        }
45        deque[nextFree++] = value;
46    }
47
48    /**
49     * Pop an int value
50     * @return value
51     */
52    public int pop() {
53        return deque[--nextFree];
54    }
55
56    /**
57     * Peek
58     * @return top value
59     */
60    public int peek() {
61        return deque[nextFree - 1];
62    }
63
64    /**
65     * Get the value of the top element and increment it.
66     * @return top value
67     */
68    public int getAndIncrement() {
69        return deque[nextFree - 1]++;
70    }
71
72    /**
73     * Decrement the value of the top element and return it.
74     * @return decremented top value
75     */
76    public int decrementAndGet() {
77        return --deque[nextFree - 1];
78    }
79
80    /**
81     * Check if deque is empty
82     * @return true if empty
83     */
84    public boolean isEmpty() {
85        return nextFree == 0;
86    }
87}
88