net.sourceforge.phpeclipse/src/net/sourceforge/phpdt/internal/compiler/util/HashtableOfPackage.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.PackageBinding;
  15
  16 public final class HashtableOfPackage {
  17         // to avoid using Enumerations, walk the individual tables skipping nulls
  18         public char[] keyTable[];
  19         public PackageBinding valueTable[];
  20
  21         int elementSize; // number of elements in the table
  22         int threshold;
  23 public HashtableOfPackage() {
  24         this(3); // usually not very large
  25 }
  26 public HashtableOfPackage(int size) {
  27         this.elementSize = 0;
  28         this.threshold = size; // size represents the expected number of elements
  29         int extraRoom = (int) (size * 1.75f);
  30         if (this.threshold == extraRoom)
  31                 extraRoom++;
  32         this.keyTable = new char[extraRoom][];
  33         this.valueTable = new PackageBinding[extraRoom];
  34 }
  35 public boolean containsKey(char[] key) {
  36         int index = CharOperation.hashCode(key) % valueTable.length;
  37         int keyLength = key.length;
  38         char[] currentKey;
  39         while ((currentKey = keyTable[index]) != null) {
  40                 if (currentKey.length == keyLength && CharOperation.prefixEquals(currentKey, key))
  41                         return true;
  42                 index = (index + 1) % keyTable.length;
  43         }
  44         return false;
  45 }
  46 public PackageBinding get(char[] key) {
  47         int index = CharOperation.hashCode(key) % valueTable.length;
  48         int keyLength = key.length;
  49         char[] currentKey;
  50         while ((currentKey = keyTable[index]) != null) {
  51                 if (currentKey.length == keyLength && CharOperation.prefixEquals(currentKey, key))
  52                         return valueTable[index];
  53                 index = (index + 1) % keyTable.length;
  54         }
  55         return null;
  56 }
  57 public PackageBinding put(char[] key, PackageBinding value) {
  58         int index = CharOperation.hashCode(key) % valueTable.length;
  59         int keyLength = key.length;
  60         char[] currentKey;
  61         while ((currentKey = keyTable[index]) != null) {
  62                 if (currentKey.length == keyLength && CharOperation.prefixEquals(currentKey, key))
  63                         return valueTable[index] = value;
  64                 index = (index + 1) % keyTable.length;
  65         }
  66         keyTable[index] = key;
  67         valueTable[index] = value;
  68
  69         // assumes the threshold is never equal to the size of the table
  70         if (++elementSize > threshold)
  71                 rehash();
  72         return value;
  73 }
  74 private void rehash() {
  75         HashtableOfPackage newHashtable = new HashtableOfPackage(elementSize * 2); // double the number of expected elements
  76         char[] currentKey;
  77         for (int i = keyTable.length; --i >= 0;)
  78                 if ((currentKey = keyTable[i]) != null)
  79                         newHashtable.put(currentKey, valueTable[i]);
  80
  81         this.keyTable = newHashtable.keyTable;
  82         this.valueTable = newHashtable.valueTable;
  83         this.threshold = newHashtable.threshold;
  84 }
  85 public int size() {
  86         return elementSize;
  87 }
  88 public String toString() {
  89         String s = ""; //$NON-NLS-1$
  90         PackageBinding pkg;
  91         for (int i = 0, length = valueTable.length; i < length; i++)
  92                 if ((pkg = valueTable[i]) != null)
  93                         s += pkg.toString() + "\n"; //$NON-NLS-1$
  94         return s;
  95 }
  96 }