1 /* 2 * Licensed to the Apache Software Foundation (ASF) under one 3 * or more contributor license agreements. See the NOTICE file 4 * distributed with this work for additional information 5 * regarding copyright ownership. The ASF licenses this file 6 * to you under the Apache License, Version 2.0 (the "License"); 7 * you may not use this file except in compliance with the License. 8 * You may obtain a copy of the License at 9 * 10 * http://www.apache.org/licenses/LICENSE-2.0 11 * 12 * Unless required by applicable law or agreed to in writing, software 13 * distributed under the License is distributed on an "AS IS" BASIS, 14 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 15 * See the License for the specific language governing permissions and 16 * limitations under the License. 17 */ 18 /* 19 * $Id: BoolStack.java 468655 2006-10-28 07:12:06Z minchau $ 20 */ 21 package org.apache.xml.utils; 22 23 24 /** 25 * Simple stack for boolean values. 26 * @xsl.usage internal 27 */ 28 public final class BoolStack implements Cloneable 29 { 30 31 /** Array of boolean values */ 32 private boolean m_values[]; 33 34 /** Array size allocated */ 35 private int m_allocatedSize; 36 37 /** Index into the array of booleans */ 38 private int m_index; 39 40 /** 41 * Default constructor. Note that the default 42 * block size is very small, for small lists. 43 */ BoolStack()44 public BoolStack() 45 { 46 this(32); 47 } 48 49 /** 50 * Construct a IntVector, using the given block size. 51 * 52 * @param size array size to allocate 53 */ BoolStack(int size)54 public BoolStack(int size) 55 { 56 57 m_allocatedSize = size; 58 m_values = new boolean[size]; 59 m_index = -1; 60 } 61 62 /** 63 * Get the length of the list. 64 * 65 * @return Current length of the list 66 */ size()67 public final int size() 68 { 69 return m_index + 1; 70 } 71 72 /** 73 * Clears the stack. 74 * 75 */ clear()76 public final void clear() 77 { 78 m_index = -1; 79 } 80 81 /** 82 * Pushes an item onto the top of this stack. 83 * 84 * 85 * @param val the boolean to be pushed onto this stack. 86 * @return the <code>item</code> argument. 87 */ push(boolean val)88 public final boolean push(boolean val) 89 { 90 91 if (m_index == m_allocatedSize - 1) 92 grow(); 93 94 return (m_values[++m_index] = val); 95 } 96 97 /** 98 * Removes the object at the top of this stack and returns that 99 * object as the value of this function. 100 * 101 * @return The object at the top of this stack. 102 * @throws EmptyStackException if this stack is empty. 103 */ pop()104 public final boolean pop() 105 { 106 return m_values[m_index--]; 107 } 108 109 /** 110 * Removes the object at the top of this stack and returns the 111 * next object at the top as the value of this function. 112 * 113 * 114 * @return Next object to the top or false if none there 115 */ popAndTop()116 public final boolean popAndTop() 117 { 118 119 m_index--; 120 121 return (m_index >= 0) ? m_values[m_index] : false; 122 } 123 124 /** 125 * Set the item at the top of this stack 126 * 127 * 128 * @param b Object to set at the top of this stack 129 */ setTop(boolean b)130 public final void setTop(boolean b) 131 { 132 m_values[m_index] = b; 133 } 134 135 /** 136 * Looks at the object at the top of this stack without removing it 137 * from the stack. 138 * 139 * @return the object at the top of this stack. 140 * @throws EmptyStackException if this stack is empty. 141 */ peek()142 public final boolean peek() 143 { 144 return m_values[m_index]; 145 } 146 147 /** 148 * Looks at the object at the top of this stack without removing it 149 * from the stack. If the stack is empty, it returns false. 150 * 151 * @return the object at the top of this stack. 152 */ peekOrFalse()153 public final boolean peekOrFalse() 154 { 155 return (m_index > -1) ? m_values[m_index] : false; 156 } 157 158 /** 159 * Looks at the object at the top of this stack without removing it 160 * from the stack. If the stack is empty, it returns true. 161 * 162 * @return the object at the top of this stack. 163 */ peekOrTrue()164 public final boolean peekOrTrue() 165 { 166 return (m_index > -1) ? m_values[m_index] : true; 167 } 168 169 /** 170 * Tests if this stack is empty. 171 * 172 * @return <code>true</code> if this stack is empty; 173 * <code>false</code> otherwise. 174 */ isEmpty()175 public boolean isEmpty() 176 { 177 return (m_index == -1); 178 } 179 180 /** 181 * Grows the size of the stack 182 * 183 */ grow()184 private void grow() 185 { 186 187 m_allocatedSize *= 2; 188 189 boolean newVector[] = new boolean[m_allocatedSize]; 190 191 System.arraycopy(m_values, 0, newVector, 0, m_index + 1); 192 193 m_values = newVector; 194 } 195 clone()196 public Object clone() 197 throws CloneNotSupportedException 198 { 199 return super.clone(); 200 } 201 202 } 203