net.sourceforge.phpeclipse/src/net/sourceforge/phpdt/internal/compiler/util/HashtableOfType.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 import net.sourceforge.phpdt.internal.compiler.lookup.ReferenceBinding;
  15
  16 public final class HashtableOfType {
  17         // to avoid using Enumerations, walk the individual tables skipping nulls
  18         public char[] keyTable[];
  19
  20         public ReferenceBinding valueTable[];
  21
  22         int elementSize; // number of elements in the table
  23
  24         int threshold;
  25
  26         public HashtableOfType() {
  27                 this(3);
  28         }
  29
  30         public HashtableOfType(int size) {
  31                 this.elementSize = 0;
  32                 this.threshold = size; // size represents the expected number of
  33                                                                 // elements
  34                 int extraRoom = (int) (size * 1.75f);
  35                 if (this.threshold == extraRoom)
  36                         extraRoom++;
  37                 this.keyTable = new char[extraRoom][];
  38                 this.valueTable = new ReferenceBinding[extraRoom];
  39         }
  40
  41         public boolean containsKey(char[] key) {
  42                 int index = CharOperation.hashCode(key) % valueTable.length;
  43                 int keyLength = key.length;
  44                 char[] currentKey;
  45                 while ((currentKey = keyTable[index]) != null) {
  46                         if (currentKey.length == keyLength
  47                                         && CharOperation.prefixEquals(currentKey, key))
  48                                 return true;
  49                         index = (index + 1) % keyTable.length;
  50                 }
  51                 return false;
  52         }
  53
  54         public ReferenceBinding get(char[] key) {
  55                 int index = CharOperation.hashCode(key) % valueTable.length;
  56                 int keyLength = key.length;
  57                 char[] currentKey;
  58                 while ((currentKey = keyTable[index]) != null) {
  59                         if (currentKey.length == keyLength
  60                                         && CharOperation.prefixEquals(currentKey, key))
  61                                 return valueTable[index];
  62                         index = (index + 1) % keyTable.length;
  63                 }
  64                 return null;
  65         }
  66
  67         public ReferenceBinding put(char[] key, ReferenceBinding value) {
  68                 int index = CharOperation.hashCode(key) % valueTable.length;
  69                 int keyLength = key.length;
  70                 char[] currentKey;
  71                 while ((currentKey = keyTable[index]) != null) {
  72                         if (currentKey.length == keyLength
  73                                         && CharOperation.prefixEquals(currentKey, key))
  74                                 return valueTable[index] = value;
  75                         index = (index + 1) % keyTable.length;
  76                 }
  77                 keyTable[index] = key;
  78                 valueTable[index] = value;
  79
  80                 // assumes the threshold is never equal to the size of the table
  81                 if (++elementSize > threshold)
  82                         rehash();
  83                 return value;
  84         }
  85
  86         private void rehash() {
  87                 HashtableOfType newHashtable = new HashtableOfType(
  88                                 elementSize < 100 ? 100 : elementSize * 2); // double the number
  89                                                                                                                         // of expected
  90                                                                                                                         // elements
  91                 char[] currentKey;
  92                 for (int i = keyTable.length; --i >= 0;)
  93                         if ((currentKey = keyTable[i]) != null)
  94                                 newHashtable.put(currentKey, valueTable[i]);
  95
  96                 this.keyTable = newHashtable.keyTable;
  97                 this.valueTable = newHashtable.valueTable;
  98                 this.threshold = newHashtable.threshold;
  99         }
 100
 101         public int size() {
 102                 return elementSize;
 103         }
 104
 105         public String toString() {
 106                 String s = ""; //$NON-NLS-1$
 107                 ReferenceBinding type;
 108                 for (int i = 0, length = valueTable.length; i < length; i++)
 109                         if ((type = valueTable[i]) != null)
 110                                 s += type.toString() + "\n"; //$NON-NLS-1$
 111                 return s;
 112         }
 113 }