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: IntStack.java 468655 2006-10-28 07:12:06Z minchau $ 20 */ 21 package org.apache.xml.utils; 22 23 import java.util.EmptyStackException; 24 25 /** 26 * Implement a stack of simple integers. 27 * 28 * %OPT% 29 * This is currently based on IntVector, which permits fast acess but pays a 30 * heavy recopying penalty if/when its size is increased. If we expect deep 31 * stacks, we should consider a version based on ChunkedIntVector. 32 * @xsl.usage internal 33 */ 34 public class IntStack extends IntVector 35 { 36 37 /** 38 * Default constructor. Note that the default 39 * block size is very small, for small lists. 40 */ 41 public IntStack() 42 { 43 super(); 44 } 45 46 /** 47 * Construct a IntVector, using the given block size. 48 * 49 * @param blocksize Size of block to allocate 50 */ 51 public IntStack(int blocksize) 52 { 53 super(blocksize); 54 } 55 56 /** 57 * Copy constructor for IntStack 58 * 59 * @param v IntStack to copy 60 */ 61 public IntStack (IntStack v) 62 { 63 super(v); 64 } 65 66 /** 67 * Pushes an item onto the top of this stack. 68 * 69 * @param i the int to be pushed onto this stack. 70 * @return the <code>item</code> argument. 71 */ 72 public int push(int i) 73 { 74 75 if ((m_firstFree + 1) >= m_mapSize) 76 { 77 m_mapSize += m_blocksize; 78 79 int newMap[] = new int[m_mapSize]; 80 81 System.arraycopy(m_map, 0, newMap, 0, m_firstFree + 1); 82 83 m_map = newMap; 84 } 85 86 m_map[m_firstFree] = i; 87 88 m_firstFree++; 89 90 return i; 91 } 92 93 /** 94 * Removes the object at the top of this stack and returns that 95 * object as the value of this function. 96 * 97 * @return The object at the top of this stack. 98 */ 99 public final int pop() 100 { 101 return m_map[--m_firstFree]; 102 } 103 104 /** 105 * Quickly pops a number of items from the stack. 106 */ 107 108 public final void quickPop(int n) 109 { 110 m_firstFree -= n; 111 } 112 113 /** 114 * Looks at the object at the top of this stack without removing it 115 * from the stack. 116 * 117 * @return the object at the top of this stack. 118 * @throws EmptyStackException if this stack is empty. 119 */ 120 public final int peek() 121 { 122 try { 123 return m_map[m_firstFree - 1]; 124 } 125 catch (ArrayIndexOutOfBoundsException e) 126 { 127 throw new EmptyStackException(); 128 } 129 } 130 131 /** 132 * Looks at the object at the position the stack counting down n items. 133 * 134 * @param n The number of items down, indexed from zero. 135 * @return the object at n items down. 136 * @throws EmptyStackException if this stack is empty. 137 */ 138 public int peek(int n) 139 { 140 try { 141 return m_map[m_firstFree-(1+n)]; 142 } 143 catch (ArrayIndexOutOfBoundsException e) 144 { 145 throw new EmptyStackException(); 146 } 147 } 148 149 /** 150 * Sets an object at a the top of the statck 151 * 152 * 153 * @param val object to set at the top 154 * @throws EmptyStackException if this stack is empty. 155 */ 156 public void setTop(int val) 157 { 158 try { 159 m_map[m_firstFree - 1] = val; 160 } 161 catch (ArrayIndexOutOfBoundsException e) 162 { 163 throw new EmptyStackException(); 164 } 165 } 166 167 /** 168 * Tests if this stack is empty. 169 * 170 * @return <code>true</code> if this stack is empty; 171 * <code>false</code> otherwise. 172 * @since JDK1.0 173 */ 174 public boolean empty() 175 { 176 return m_firstFree == 0; 177 } 178 179 /** 180 * Returns where an object is on this stack. 181 * 182 * @param o the desired object. 183 * @return the distance from the top of the stack where the object is] 184 * located; the return value <code>-1</code> indicates that the 185 * object is not on the stack. 186 * @since JDK1.0 187 */ 188 public int search(int o) 189 { 190 191 int i = lastIndexOf(o); 192 193 if (i >= 0) 194 { 195 return size() - i; 196 } 197 198 return -1; 199 } 200 201 /** 202 * Returns clone of current IntStack 203 * 204 * @return clone of current IntStack 205 */ 206 public Object clone() 207 throws CloneNotSupportedException 208 { 209 return (IntStack) super.clone(); 210 } 211 } 212
