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 26 package jdk.nashorn.internal; 27 28 /** 29 * Small helper class for fast int deques 30 */ 31 public 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 }