net.sourceforge.phpeclipse/src/net/sourceforge/phpdt/internal/compiler/util/HashtableOfInt.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 /**
  14  * Hashtable for non-zero int keys.
  15  */
  16
  17 public final class HashtableOfInt {
  18         // to avoid using Enumerations, walk the individual tables skipping nulls
  19         public int[] keyTable;
  20
  21         public Object[] valueTable;
  22
  23         int elementSize; // number of elements in the table
  24
  25         int threshold;
  26
  27         public HashtableOfInt() {
  28                 this(13);
  29         }
  30
  31         public HashtableOfInt(int size) {
  32                 this.elementSize = 0;
  33                 this.threshold = size; // size represents the expected number of
  34                                                                 // elements
  35                 int extraRoom = (int) (size * 1.75f);
  36                 if (this.threshold == extraRoom)
  37                         extraRoom++;
  38                 this.keyTable = new int[extraRoom];
  39                 this.valueTable = new Object[extraRoom];
  40         }
  41
  42         public boolean containsKey(int key) {
  43                 int index = key % valueTable.length;
  44                 int currentKey;
  45                 while ((currentKey = keyTable[index]) != 0) {
  46                         if (currentKey == key)
  47                                 return true;
  48                         index = (index + 1) % keyTable.length;
  49                 }
  50                 return false;
  51         }
  52
  53         public Object get(int key) {
  54                 int index = key % valueTable.length;
  55                 int currentKey;
  56                 while ((currentKey = keyTable[index]) != 0) {
  57                         if (currentKey == key)
  58                                 return valueTable[index];
  59                         index = (index + 1) % keyTable.length;
  60                 }
  61                 return null;
  62         }
  63
  64         public Object put(int key, Object value) {
  65                 int index = key % valueTable.length;
  66                 int currentKey;
  67                 while ((currentKey = keyTable[index]) != 0) {
  68                         if (currentKey == key)
  69                                 return valueTable[index] = value;
  70                         index = (index + 1) % keyTable.length;
  71                 }
  72                 keyTable[index] = key;
  73                 valueTable[index] = value;
  74
  75                 // assumes the threshold is never equal to the size of the table
  76                 if (++elementSize > threshold)
  77                         rehash();
  78                 return value;
  79         }
  80
  81         private void rehash() {
  82                 HashtableOfInt newHashtable = new HashtableOfInt(elementSize * 2); // double
  83                                                                                                                                                         // the
  84                                                                                                                                                         // number
  85                                                                                                                                                         // of
  86                                                                                                                                                         // expected
  87                                                                                                                                                         // elements
  88                 int currentKey;
  89                 for (int i = keyTable.length; --i >= 0;)
  90                         if ((currentKey = keyTable[i]) != 0)
  91                                 newHashtable.put(currentKey, valueTable[i]);
  92
  93                 this.keyTable = newHashtable.keyTable;
  94                 this.valueTable = newHashtable.valueTable;
  95                 this.threshold = newHashtable.threshold;
  96         }
  97
  98         public int size() {
  99                 return elementSize;
 100         }
 101
 102         public String toString() {
 103                 String s = ""; //$NON-NLS-1$
 104                 Object object;
 105                 for (int i = 0, length = valueTable.length; i < length; i++)
 106                         if ((object = valueTable[i]) != null)
 107                                 s += keyTable[i] + " -> " + object.toString() + "\n"; //$NON-NLS-2$ //$NON-NLS-1$
 108                 return s;
 109         }
 110 }