DoubleCache


1   /*******************************************************************************
2    * Copyright (c) 2000, 2006 IBM Corporation and others.
3    * All rights reserved. This program and the accompanying materials
4    * are made available under the terms of the Eclipse Public License v1.0
5    * which accompanies this distribution, and is available at
6    * http://www.eclipse.org/legal/epl-v10.html
7    *
8    * Contributors:
9    *     IBM Corporation - initial API and implementation
10   *******************************************************************************/
11  package org.eclipse.jdt.internal.compiler.codegen;
12  
13  public class DoubleCache {
14      private double keyTable[];
15      private int valueTable[]; 
16      private int elementSize;
17  /**
18   * Constructs a new, empty hashtable. A default capacity and
19   * load factor is used. Note that the hashtable will automatically 
20   * grow when it gets full.
21   */
22  public DoubleCache() {
23      this(13);
24  }
25  /**
26   * Constructs a new, empty hashtable with the specified initial
27   * capacity.
28   * @param initialCapacity int
29   *  the initial number of buckets
30   */
31  public DoubleCache(int initialCapacity) {
32      this.elementSize = 0;
33      this.keyTable = new double[initialCapacity];
34      this.valueTable = new int[initialCapacity];
35  }
36  /**
37   * Clears the hash table so that it has no more elements in it.
38   */
39  public void clear() {
40      for (int i = this.keyTable.length; --i >= 0;) {
41          this.keyTable[i] = 0.0;
42          this.valueTable[i] = 0;
43      }
44      this.elementSize = 0;
45  }
46  /** Returns true if the collection contains an element for the key.
47   *
48   * @param key <CODE>double</CODE> the key that we are looking for
49   * @return boolean
50   */
51  public boolean containsKey(double key) {
52      if (key == 0.0) {
53          for (int i = 0, max = this.elementSize; i < max; i++) {
54              if (this.keyTable[i] == 0.0) {
55                  long value1 = Double.doubleToLongBits(key);
56                  long value2 = Double.doubleToLongBits(this.keyTable[i]);
57                  if (value1 == -9223372036854775808L && value2 == -9223372036854775808L)
58                      return true;
59                  if (value1 == 0 && value2 == 0)
60                      return true;
61              }
62          }
63      } else {
64          for (int i = 0, max = this.elementSize; i < max; i++) {
65              if (this.keyTable[i] == key) {
66                  return true;
67              }
68          }
69      }
70      return false;
71  }
72  /**
73   * Puts the specified element into the hashtable, using the specified
74   * key.  The element may be retrieved by doing a get() with the same key.
75   * 
76   * @param key <CODE>double</CODE> the specified key in the hashtable
77   * @param value <CODE>int</CODE> the specified element
78   * @return int value
79   */
80  public int put(double key, int value) {
81      if (this.elementSize == this.keyTable.length) {
82          // resize
83          System.arraycopy(this.keyTable, 0, (this.keyTable = new double[this.elementSize * 2]), 0, this.elementSize);
84          System.arraycopy(this.valueTable, 0, (this.valueTable = new int[this.elementSize * 2]), 0, this.elementSize);
85      }
86      this.keyTable[this.elementSize] = key;
87      this.valueTable[this.elementSize] = value;
88      this.elementSize++;
89      return value;
90  }
91  /**
92   * Puts the specified element into the hashtable, using the specified
93   * key.  The element may be retrieved by doing a get() with the same key.
94   * 
95   * @param key <CODE>double</CODE> the specified key in the hashtable
96   * @param value <CODE>int</CODE> the specified element
97   * @return int value
98   */
99  public int putIfAbsent(double key, int value) {
100     if (key == 0.0) {
101         for (int i = 0, max = this.elementSize; i < max; i++) {
102             if (this.keyTable[i] == 0.0) {
103                 long value1 = Double.doubleToLongBits(key);
104                 long value2 = Double.doubleToLongBits(this.keyTable[i]);
105                 if (value1 == -9223372036854775808L && value2 == -9223372036854775808L)
106                     return this.valueTable[i];
107                 if (value1 == 0 && value2 == 0)
108                     return this.valueTable[i];
109             }
110         }
111     } else {
112         for (int i = 0, max = this.elementSize; i < max; i++) {
113             if (this.keyTable[i] == key) {
114                 return this.valueTable[i];
115             }
116         }
117     }
118     if (this.elementSize == this.keyTable.length) {
119         // resize
120         System.arraycopy(this.keyTable, 0, (this.keyTable = new double[this.elementSize * 2]), 0, this.elementSize);
121         System.arraycopy(this.valueTable, 0, (this.valueTable = new int[this.elementSize * 2]), 0, this.elementSize);
122     }
123     this.keyTable[this.elementSize] = key;
124     this.valueTable[this.elementSize] = value;
125     this.elementSize++;
126     return -value; // negative when added, assumes value is > 0
127 }
128 /**
129  * Converts to a rather lengthy String.
130  *
131  * @return String the ascii representation of the receiver
132  */
133 public String   toString() {
134     int max = this.elementSize;
135     StringBuffer   buf = new StringBuffer  ();
136     buf.append("{"); //$NON-NLS-1$
137     for (int i = 0; i < max; ++i) {
138         if ((this.keyTable[i] != 0) || ((this.keyTable[i] == 0) &&(this.valueTable[i] != 0))) {
139             buf.append(this.keyTable[i]).append("->").append(this.valueTable[i]); //$NON-NLS-1$
140         }
141         if (i < max) {
142             buf.append(", "); //$NON-NLS-1$
143         }
144     }
145     buf.append("}"); //$NON-NLS-1$
146     return buf.toString();
147 }
148 }
149
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