Thu, 31 Aug 2017 15:18:52 +0800
merge
aoqi@0 | 1 | /* |
aoqi@0 | 2 | * Copyright (c) 1997, 2011, Oracle and/or its affiliates. All rights reserved. |
aoqi@0 | 3 | * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
aoqi@0 | 4 | * |
aoqi@0 | 5 | * This code is free software; you can redistribute it and/or modify it |
aoqi@0 | 6 | * under the terms of the GNU General Public License version 2 only, as |
aoqi@0 | 7 | * published by the Free Software Foundation. Oracle designates this |
aoqi@0 | 8 | * particular file as subject to the "Classpath" exception as provided |
aoqi@0 | 9 | * by Oracle in the LICENSE file that accompanied this code. |
aoqi@0 | 10 | * |
aoqi@0 | 11 | * This code is distributed in the hope that it will be useful, but WITHOUT |
aoqi@0 | 12 | * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
aoqi@0 | 13 | * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
aoqi@0 | 14 | * version 2 for more details (a copy is included in the LICENSE file that |
aoqi@0 | 15 | * accompanied this code). |
aoqi@0 | 16 | * |
aoqi@0 | 17 | * You should have received a copy of the GNU General Public License version |
aoqi@0 | 18 | * 2 along with this work; if not, write to the Free Software Foundation, |
aoqi@0 | 19 | * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
aoqi@0 | 20 | * |
aoqi@0 | 21 | * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
aoqi@0 | 22 | * or visit www.oracle.com if you need additional information or have any |
aoqi@0 | 23 | * questions. |
aoqi@0 | 24 | */ |
aoqi@0 | 25 | |
aoqi@0 | 26 | package com.sun.xml.internal.bind.v2.util; |
aoqi@0 | 27 | |
aoqi@0 | 28 | import java.util.AbstractList; |
aoqi@0 | 29 | import java.util.Arrays; |
aoqi@0 | 30 | import java.util.List; |
aoqi@0 | 31 | import java.util.Stack; |
aoqi@0 | 32 | |
aoqi@0 | 33 | /** |
aoqi@0 | 34 | * {@link Stack}-like data structure that allows the following efficient operations: |
aoqi@0 | 35 | * |
aoqi@0 | 36 | * <ol> |
aoqi@0 | 37 | * <li>Push/pop operation. |
aoqi@0 | 38 | * <li>Duplicate check. When an object that's already in the stack is pushed, |
aoqi@0 | 39 | * this class will tell you so. |
aoqi@0 | 40 | * </ol> |
aoqi@0 | 41 | * |
aoqi@0 | 42 | * <p> |
aoqi@0 | 43 | * Object equality is their identity equality. |
aoqi@0 | 44 | * |
aoqi@0 | 45 | * <p> |
aoqi@0 | 46 | * This class implements {@link List} for accessing items in the stack, |
aoqi@0 | 47 | * but {@link List} methods that alter the stack is not supported. |
aoqi@0 | 48 | * |
aoqi@0 | 49 | * @author Kohsuke Kawaguchi |
aoqi@0 | 50 | */ |
aoqi@0 | 51 | public final class CollisionCheckStack<E> extends AbstractList<E> { |
aoqi@0 | 52 | private Object[] data; |
aoqi@0 | 53 | private int[] next; |
aoqi@0 | 54 | private int size = 0; |
aoqi@0 | 55 | |
aoqi@0 | 56 | private boolean latestPushResult = false; |
aoqi@0 | 57 | |
aoqi@0 | 58 | /** |
aoqi@0 | 59 | * True if the check shall be done by using the object identity. |
aoqi@0 | 60 | * False if the check shall be done with the equals method. |
aoqi@0 | 61 | */ |
aoqi@0 | 62 | private boolean useIdentity = true; |
aoqi@0 | 63 | |
aoqi@0 | 64 | // for our purpose, there isn't much point in resizing this as we don't expect |
aoqi@0 | 65 | // the stack to grow that much. |
aoqi@0 | 66 | private final int[] initialHash; |
aoqi@0 | 67 | |
aoqi@0 | 68 | public CollisionCheckStack() { |
aoqi@0 | 69 | initialHash = new int[17]; |
aoqi@0 | 70 | data = new Object[16]; |
aoqi@0 | 71 | next = new int[16]; |
aoqi@0 | 72 | } |
aoqi@0 | 73 | |
aoqi@0 | 74 | /** |
aoqi@0 | 75 | * Set to false to use {@link Object#equals(Object)} to detect cycles. |
aoqi@0 | 76 | * This method can be only used when the stack is empty. |
aoqi@0 | 77 | */ |
aoqi@0 | 78 | public void setUseIdentity(boolean useIdentity) { |
aoqi@0 | 79 | this.useIdentity = useIdentity; |
aoqi@0 | 80 | } |
aoqi@0 | 81 | |
aoqi@0 | 82 | public boolean getUseIdentity() { |
aoqi@0 | 83 | return useIdentity; |
aoqi@0 | 84 | } |
aoqi@0 | 85 | |
aoqi@0 | 86 | public boolean getLatestPushResult() { |
aoqi@0 | 87 | return latestPushResult; |
aoqi@0 | 88 | } |
aoqi@0 | 89 | |
aoqi@0 | 90 | /** |
aoqi@0 | 91 | * Pushes a new object to the stack. |
aoqi@0 | 92 | * |
aoqi@0 | 93 | * @return |
aoqi@0 | 94 | * true if this object has already been pushed |
aoqi@0 | 95 | */ |
aoqi@0 | 96 | public boolean push(E o) { |
aoqi@0 | 97 | if(data.length==size) |
aoqi@0 | 98 | expandCapacity(); |
aoqi@0 | 99 | |
aoqi@0 | 100 | data[size] = o; |
aoqi@0 | 101 | int hash = hash(o); |
aoqi@0 | 102 | boolean r = findDuplicate(o, hash); |
aoqi@0 | 103 | next[size] = initialHash[hash]; |
aoqi@0 | 104 | initialHash[hash] = size+1; |
aoqi@0 | 105 | size++; |
aoqi@0 | 106 | this.latestPushResult = r; |
aoqi@0 | 107 | return latestPushResult; |
aoqi@0 | 108 | } |
aoqi@0 | 109 | |
aoqi@0 | 110 | /** |
aoqi@0 | 111 | * Pushes a new object to the stack without making it participate |
aoqi@0 | 112 | * with the collision check. |
aoqi@0 | 113 | */ |
aoqi@0 | 114 | public void pushNocheck(E o) { |
aoqi@0 | 115 | if(data.length==size) |
aoqi@0 | 116 | expandCapacity(); |
aoqi@0 | 117 | data[size] = o; |
aoqi@0 | 118 | next[size] = -1; |
aoqi@0 | 119 | size++; |
aoqi@0 | 120 | } |
aoqi@0 | 121 | |
aoqi@0 | 122 | public boolean findDuplicate(E o) { |
aoqi@0 | 123 | int hash = hash(o); |
aoqi@0 | 124 | return findDuplicate(o, hash); |
aoqi@0 | 125 | } |
aoqi@0 | 126 | |
aoqi@0 | 127 | @Override |
aoqi@0 | 128 | public E get(int index) { |
aoqi@0 | 129 | return (E)data[index]; |
aoqi@0 | 130 | } |
aoqi@0 | 131 | |
aoqi@0 | 132 | @Override |
aoqi@0 | 133 | public int size() { |
aoqi@0 | 134 | return size; |
aoqi@0 | 135 | } |
aoqi@0 | 136 | |
aoqi@0 | 137 | private int hash(Object o) { |
aoqi@0 | 138 | return ((useIdentity?System.identityHashCode(o):o.hashCode())&0x7FFFFFFF) % initialHash.length; |
aoqi@0 | 139 | } |
aoqi@0 | 140 | |
aoqi@0 | 141 | /** |
aoqi@0 | 142 | * Pops an object from the stack |
aoqi@0 | 143 | */ |
aoqi@0 | 144 | public E pop() { |
aoqi@0 | 145 | size--; |
aoqi@0 | 146 | Object o = data[size]; |
aoqi@0 | 147 | data[size] = null; // keeping references too long == memory leak |
aoqi@0 | 148 | int n = next[size]; |
aoqi@0 | 149 | if(n<0) { |
aoqi@0 | 150 | // pushed by nocheck. no need to update hash |
aoqi@0 | 151 | } else { |
aoqi@0 | 152 | int hash = hash(o); |
aoqi@0 | 153 | assert initialHash[hash]==size+1; |
aoqi@0 | 154 | initialHash[hash] = n; |
aoqi@0 | 155 | } |
aoqi@0 | 156 | return (E)o; |
aoqi@0 | 157 | } |
aoqi@0 | 158 | |
aoqi@0 | 159 | /** |
aoqi@0 | 160 | * Returns the top of the stack. |
aoqi@0 | 161 | */ |
aoqi@0 | 162 | public E peek() { |
aoqi@0 | 163 | return (E)data[size-1]; |
aoqi@0 | 164 | } |
aoqi@0 | 165 | |
aoqi@0 | 166 | private boolean findDuplicate(E o, int hash) { |
aoqi@0 | 167 | int p = initialHash[hash]; |
aoqi@0 | 168 | while(p!=0) { |
aoqi@0 | 169 | p--; |
aoqi@0 | 170 | Object existing = data[p]; |
aoqi@0 | 171 | if (useIdentity) { |
aoqi@0 | 172 | if(existing==o) return true; |
aoqi@0 | 173 | } else { |
aoqi@0 | 174 | if (o.equals(existing)) return true; |
aoqi@0 | 175 | } |
aoqi@0 | 176 | p = next[p]; |
aoqi@0 | 177 | } |
aoqi@0 | 178 | return false; |
aoqi@0 | 179 | } |
aoqi@0 | 180 | |
aoqi@0 | 181 | private void expandCapacity() { |
aoqi@0 | 182 | int oldSize = data.length; |
aoqi@0 | 183 | int newSize = oldSize * 2; |
aoqi@0 | 184 | Object[] d = new Object[newSize]; |
aoqi@0 | 185 | int[] n = new int[newSize]; |
aoqi@0 | 186 | |
aoqi@0 | 187 | System.arraycopy(data,0,d,0,oldSize); |
aoqi@0 | 188 | System.arraycopy(next,0,n,0,oldSize); |
aoqi@0 | 189 | |
aoqi@0 | 190 | data = d; |
aoqi@0 | 191 | next = n; |
aoqi@0 | 192 | } |
aoqi@0 | 193 | |
aoqi@0 | 194 | /** |
aoqi@0 | 195 | * Clears all the contents in the stack. |
aoqi@0 | 196 | */ |
aoqi@0 | 197 | public void reset() { |
aoqi@0 | 198 | if(size>0) { |
aoqi@0 | 199 | size = 0; |
aoqi@0 | 200 | Arrays.fill(initialHash,0); |
aoqi@0 | 201 | } |
aoqi@0 | 202 | } |
aoqi@0 | 203 | |
aoqi@0 | 204 | /** |
aoqi@0 | 205 | * String that represents the cycle. |
aoqi@0 | 206 | */ |
aoqi@0 | 207 | public String getCycleString() { |
aoqi@0 | 208 | StringBuilder sb = new StringBuilder(); |
aoqi@0 | 209 | int i=size()-1; |
aoqi@0 | 210 | E obj = get(i); |
aoqi@0 | 211 | sb.append(obj); |
aoqi@0 | 212 | Object x; |
aoqi@0 | 213 | do { |
aoqi@0 | 214 | sb.append(" -> "); |
aoqi@0 | 215 | x = get(--i); |
aoqi@0 | 216 | sb.append(x); |
aoqi@0 | 217 | } while(obj!=x); |
aoqi@0 | 218 | |
aoqi@0 | 219 | return sb.toString(); |
aoqi@0 | 220 | } |
aoqi@0 | 221 | } |