net.sourceforge.phpeclipse/src/net/sourceforge/phpdt/internal/compiler/util/HashtableOfObject.java

   1 /*******************************************************************************
   2  * Copyright (c) 2000, 2003 IBM Corporation and others.
   3  * All rights reserved. This program and the accompanying materials
   4  * are made available under the terms of the Common Public License v1.0
   5  * which accompanies this distribution, and is available at
   6  * http://www.eclipse.org/legal/cpl-v10.html
   7  *
   8  * Contributors:
   9  *     IBM Corporation - initial API and implementation
  10  *******************************************************************************/
  11 package net.sourceforge.phpdt.internal.compiler.util;
  12
  13 import net.sourceforge.phpdt.core.compiler.CharOperation;
  14
  15 /**
  16  * Hashtable of {char[] --> Object }
  17  */
  18 public final class HashtableOfObject implements Cloneable {
  19
  20         // to avoid using Enumerations, walk the individual tables skipping nulls
  21         public char[] keyTable[];
  22
  23         public Object valueTable[];
  24
  25         public int elementSize; // number of elements in the table
  26
  27         int threshold;
  28
  29         public HashtableOfObject() {
  30                 this(13);
  31         }
  32
  33         public HashtableOfObject(int size) {
  34
  35                 this.elementSize = 0;
  36                 this.threshold = size; // size represents the expected number of
  37                                                                 // elements
  38                 int extraRoom = (int) (size * 1.75f);
  39                 if (this.threshold == extraRoom)
  40                         extraRoom++;
  41                 this.keyTable = new char[extraRoom][];
  42                 this.valueTable = new Object[extraRoom];
  43         }
  44
  45         public Object clone() throws CloneNotSupportedException {
  46                 HashtableOfObject result = (HashtableOfObject) super.clone();
  47                 result.elementSize = this.elementSize;
  48                 result.threshold = this.threshold;
  49
  50                 int length = this.keyTable.length;
  51                 result.keyTable = new char[length][];
  52                 System.arraycopy(this.keyTable, 0, result.keyTable, 0, length);
  53
  54                 length = this.valueTable.length;
  55                 result.valueTable = new Object[length];
  56                 System.arraycopy(this.valueTable, 0, result.valueTable, 0, length);
  57                 return result;
  58         }
  59
  60         public boolean containsKey(char[] key) {
  61
  62                 int index = CharOperation.hashCode(key) % valueTable.length;
  63                 int keyLength = key.length;
  64                 char[] currentKey;
  65                 while ((currentKey = keyTable[index]) != null) {
  66                         if (currentKey.length == keyLength
  67                                         && CharOperation.prefixEquals(currentKey, key))
  68                                 return true;
  69                         index = (index + 1) % keyTable.length;
  70                 }
  71                 return false;
  72         }
  73
  74         public Object get(char[] key) {
  75
  76                 int index = CharOperation.hashCode(key) % valueTable.length;
  77                 int keyLength = key.length;
  78                 char[] currentKey;
  79                 while ((currentKey = keyTable[index]) != null) {
  80                         if (currentKey.length == keyLength
  81                                         && CharOperation.prefixEquals(currentKey, key))
  82                                 return valueTable[index];
  83                         index = (index + 1) % keyTable.length;
  84                 }
  85                 return null;
  86         }
  87
  88         public Object put(char[] key, Object value) {
  89
  90                 int index = CharOperation.hashCode(key) % valueTable.length;
  91                 int keyLength = key.length;
  92                 char[] currentKey;
  93                 while ((currentKey = keyTable[index]) != null) {
  94                         if (currentKey.length == keyLength
  95                                         && CharOperation.prefixEquals(currentKey, key))
  96                                 return valueTable[index] = value;
  97                         index = (index + 1) % keyTable.length;
  98                 }
  99                 keyTable[index] = key;
 100                 valueTable[index] = value;
 101
 102                 // assumes the threshold is never equal to the size of the table
 103                 if (++elementSize > threshold)
 104                         rehash();
 105                 return value;
 106         }
 107
 108         public Object removeKey(char[] key) {
 109
 110                 int index = CharOperation.hashCode(key) % valueTable.length;
 111                 int keyLength = key.length;
 112                 char[] currentKey;
 113                 while ((currentKey = keyTable[index]) != null) {
 114                         if (currentKey.length == keyLength
 115                                         && CharOperation.prefixEquals(currentKey, key)) {
 116                                 Object value = valueTable[index];
 117                                 elementSize--;
 118                                 keyTable[index] = null;
 119                                 valueTable[index] = null;
 120                                 rehash();
 121                                 return value;
 122                         }
 123                         index = (index + 1) % keyTable.length;
 124                 }
 125                 return null;
 126         }
 127
 128         private void rehash() {
 129
 130                 HashtableOfObject newHashtable = new HashtableOfObject(elementSize * 2); // double
 131                                                                                                                                                                         // the
 132                                                                                                                                                                         // number
 133                                                                                                                                                                         // of
 134                                                                                                                                                                         // expected
 135                                                                                                                                                                         // elements
 136                 char[] currentKey;
 137                 for (int i = keyTable.length; --i >= 0;)
 138                         if ((currentKey = keyTable[i]) != null)
 139                                 newHashtable.put(currentKey, valueTable[i]);
 140
 141                 this.keyTable = newHashtable.keyTable;
 142                 this.valueTable = newHashtable.valueTable;
 143                 this.threshold = newHashtable.threshold;
 144         }
 145
 146         public int size() {
 147                 return elementSize;
 148         }
 149
 150         public String toString() {
 151                 String s = ""; //$NON-NLS-1$
 152                 Object object;
 153                 for (int i = 0, length = valueTable.length; i < length; i++)
 154                         if ((object = valueTable[i]) != null)
 155                                 s += new String(keyTable[i])
 156                                                 + " -> " + object.toString() + "\n"; //$NON-NLS-2$ //$NON-NLS-1$
 157                 return s;
 158         }
 159 }