first scanner /parser copied from the jdt java version
[phpeclipse.git] / net.sourceforge.phpeclipse / src / net / sourceforge / phpdt / internal / compiler / util / HashtableOfObject.java
1 /*******************************************************************************
2  * Copyright (c) 2000, 2001, 2002 International Business Machines Corp. and others.
3  * All rights reserved. This program and the accompanying materials 
4  * are made available under the terms of the Common Public License v0.5 
5  * which accompanies this distribution, and is available at
6  * http://www.eclipse.org/legal/cpl-v05.html
7  * 
8  * Contributors:
9  *     IBM Corporation - initial API and implementation
10  ******************************************************************************/
11 package net.sourceforge.phpdt.internal.compiler.util;
12
13 /**
14  * Hashtable of {char[] --> Object }
15  */
16 public final class HashtableOfObject implements Cloneable {
17         
18         // to avoid using Enumerations, walk the individual tables skipping nulls
19         public char[] keyTable[];
20         public Object valueTable[];
21
22         public int elementSize; // number of elements in the table
23         int threshold;
24
25         public HashtableOfObject() {
26                 this(13);
27         }
28
29         public HashtableOfObject(int size) {
30
31                 this.elementSize = 0;
32                 this.threshold = size; // size represents the expected number of elements
33                 int extraRoom = (int) (size * 1.75f);
34                 if (this.threshold == extraRoom)
35                         extraRoom++;
36                 this.keyTable = new char[extraRoom][];
37                 this.valueTable = new Object[extraRoom];
38         }
39
40         public Object clone() throws CloneNotSupportedException {
41                 HashtableOfObject result = (HashtableOfObject) super.clone();
42                 result.elementSize = this.elementSize;
43                 result.threshold = this.threshold;
44
45                 int length = this.keyTable.length;
46                 result.keyTable = new char[length][];
47                 System.arraycopy(this.keyTable, 0, result.keyTable, 0, length);
48
49                 length = this.valueTable.length;
50                 result.valueTable = new Object[length];
51                 System.arraycopy(this.valueTable, 0, result.valueTable, 0, length);
52                 return result;
53         }
54
55         public boolean containsKey(char[] key) {
56
57                 int index = CharOperation.hashCode(key) % valueTable.length;
58                 int keyLength = key.length;
59                 char[] currentKey;
60                 while ((currentKey = keyTable[index]) != null) {
61                         if (currentKey.length == keyLength
62                                 && CharOperation.prefixEquals(currentKey, key))
63                                 return true;
64                         index = (index + 1) % keyTable.length;
65                 }
66                 return false;
67         }
68
69         public Object get(char[] key) {
70
71                 int index = CharOperation.hashCode(key) % valueTable.length;
72                 int keyLength = key.length;
73                 char[] currentKey;
74                 while ((currentKey = keyTable[index]) != null) {
75                         if (currentKey.length == keyLength
76                                 && CharOperation.prefixEquals(currentKey, key))
77                                 return valueTable[index];
78                         index = (index + 1) % keyTable.length;
79                 }
80                 return null;
81         }
82
83         public Object put(char[] key, Object value) {
84
85                 int index = CharOperation.hashCode(key) % valueTable.length;
86                 int keyLength = key.length;
87                 char[] currentKey;
88                 while ((currentKey = keyTable[index]) != null) {
89                         if (currentKey.length == keyLength
90                                 && CharOperation.prefixEquals(currentKey, key))
91                                 return valueTable[index] = value;
92                         index = (index + 1) % keyTable.length;
93                 }
94                 keyTable[index] = key;
95                 valueTable[index] = value;
96
97                 // assumes the threshold is never equal to the size of the table
98                 if (++elementSize > threshold)
99                         rehash();
100                 return value;
101         }
102
103         public Object removeKey(char[] key) {
104
105                 int index = CharOperation.hashCode(key) % valueTable.length;
106                 int keyLength = key.length;
107                 char[] currentKey;
108                 while ((currentKey = keyTable[index]) != null) {
109                         if (currentKey.length == keyLength
110                                 && CharOperation.prefixEquals(currentKey, key)) {
111                                         Object value = valueTable[index];
112                                         elementSize--;
113                                         keyTable[index] = null;
114                                         valueTable[index] = null;
115                                         rehash();
116                                         return value;
117                                 }
118                         index = (index + 1) % keyTable.length;
119                 }
120                 return null;
121         }
122
123         private void rehash() {
124
125                 HashtableOfObject newHashtable = new HashtableOfObject(elementSize * 2);                // double the number of expected elements
126                 char[] currentKey;
127                 for (int i = keyTable.length; --i >= 0;)
128                         if ((currentKey = keyTable[i]) != null)
129                                 newHashtable.put(currentKey, valueTable[i]);
130
131                 this.keyTable = newHashtable.keyTable;
132                 this.valueTable = newHashtable.valueTable;
133                 this.threshold = newHashtable.threshold;
134         }
135
136         public int size() {
137                 return elementSize;
138         }
139
140         public String toString() {
141                 String s = ""; //$NON-NLS-1$
142                 Object object;
143                 for (int i = 0, length = valueTable.length; i < length; i++)
144                         if ((object = valueTable[i]) != null)
145                                 s += new String(keyTable[i]) + " -> " + object.toString() + "\n";       //$NON-NLS-2$ //$NON-NLS-1$
146                 return s;
147         }
148 }