hillion 01/10/17 07:49:50 Added: sources/org/apache/batik/util SoftDoublyIndexedTable.java Log: Class moved to batik/util. Revision Changes Path 1.1 xml-batik/sources/org/apache/batik/util/SoftDoublyIndexedTable.java Index: SoftDoublyIndexedTable.java =================================================================== /***************************************************************************** * Copyright (C) The Apache Software Foundation. All rights reserved. * * ------------------------------------------------------------------------- * * This software is published under the terms of the Apache Software License * * version 1.1, a copy of which has been included with this distribution in * * the LICENSE file. * *****************************************************************************/ package org.apache.batik.util; import java.lang.ref.ReferenceQueue; import java.lang.ref.SoftReference; /** * This class represents a doubly indexed hash table, which holds * soft references to the contained values.. * * @author <a href="mailto:[EMAIL PROTECTED]";>Stephane Hillion</a> * @version $Id: SoftDoublyIndexedTable.java,v 1.1 2001/10/17 14:49:50 hillion Exp $ */ public class SoftDoublyIndexedTable { /** * The initial capacity */ protected final static int INITIAL_CAPACITY = 11; /** * The underlying array */ protected Entry[] table; /** * The number of entries */ protected int count; /** * The reference queue. */ protected ReferenceQueue referenceQueue = new ReferenceQueue(); /** * Creates a new SoftDoublyIndexedTable. */ public SoftDoublyIndexedTable() { table = new Entry[INITIAL_CAPACITY]; } /** * Creates a new DoublyIndexedTable. * @param c The inital capacity. */ public SoftDoublyIndexedTable(int c) { table = new Entry[c]; } /** * Returns the size of this table. */ public int size() { return count; } /** * Gets the value of a variable * @return the value or null */ public Object get(Object o1, Object o2) { int hash = hashCode(o1, o2) & 0x7FFFFFFF; int index = hash % table.length; for (Entry e = table[index]; e != null; e = e.next) { if ((e.hash == hash) && e.match(o1, o2)) { return e.get(); } } return null; } /** * Sets a new value for the given variable * @return the old value or null */ public Object put(Object o1, Object o2, Object value) { removeClearedEntries(); int hash = hashCode(o1, o2) & 0x7FFFFFFF; int index = hash % table.length; Entry e = table[index]; if (e != null) { if ((e.hash == hash) && e.match(o1, o2)) { Object old = e.get(); table[index] = new Entry(hash, o1, o2, value, e.next); return old; } Entry o = e; e = e.next; while (e != null) { if ((e.hash == hash) && e.match(o1, o2)) { Object old = e.get(); e = new Entry(hash, o1, o2, value, e.next); o.next = e; return old; } o = e; e = e.next; } } // The key is not in the hash table int len = table.length; if (count++ >= (len * 3) >>> 2) { rehash(); index = hash % table.length; } table[index] = new Entry(hash, o1, o2, value, table[index]); return null; } /** * Clears the table. */ public void clear() { table = new Entry[INITIAL_CAPACITY]; count = 0; referenceQueue = new ReferenceQueue(); } /** * Rehash the table */ protected void rehash () { Entry[] oldTable = table; table = new Entry[oldTable.length * 2 + 1]; for (int i = oldTable.length-1; i >= 0; i--) { for (Entry old = oldTable[i]; old != null;) { Entry e = old; old = old.next; int index = e.hash % table.length; e.next = table[index]; table[index] = e; } } } /** * Computes a hash code corresponding to the given objects. */ protected int hashCode(Object o1, Object o2) { int result = (o1 == null) ? 0 : o1.hashCode(); return result ^ ((o2 == null) ? 0 : o2.hashCode()); } /** * Removes the cleared entries. */ protected void removeClearedEntries() { Entry e; while ((e = (Entry)referenceQueue.poll()) != null) { int index = e.hash % table.length; Entry t = table[index]; if (t == e) { table[index] = e.next; } else { loop: for (;t!=null;) { Entry c = t.next; if (c == e) { t.next = e.next; break loop; } t = c; } } count--; } } /** * To manage collisions */ protected class Entry extends SoftReference { /** * The hash code */ public int hash; /** * The first key */ public Object key1; /** * The second key */ public Object key2; /** * The next entry */ public Entry next; /** * Creates a new entry */ public Entry(int hash, Object key1, Object key2, Object value, Entry next) { super(value, referenceQueue); this.hash = hash; this.key1 = key1; this.key2 = key2; this.next = next; } /** * Whether this entry match the given keys. */ public boolean match(Object o1, Object o2) { if (key1 != null) { if (!key1.equals(o1)) { return false; } } else if (o1 != null) { return false; } if (key2 != null) { return key2.equals(o2); } return o2 == null; } } }
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