1 /* CollationKey.java -- Precomputed collation value
2 Copyright (C) 1998, 1999, 2000, 2003 Free Software Foundation, Inc.
4 This file is part of GNU Classpath.
6 GNU Classpath is free software; you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by
8 the Free Software Foundation; either version 2, or (at your option)
11 GNU Classpath is distributed in the hope that it will be useful, but
12 WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 General Public License for more details.
16 You should have received a copy of the GNU General Public License
17 along with GNU Classpath; see the file COPYING. If not, write to the
18 Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
21 Linking this library statically or dynamically with other modules is
22 making a combined work based on this library. Thus, the terms and
23 conditions of the GNU General Public License cover the whole
26 As a special exception, the copyright holders of this library give you
27 permission to link this library with independent modules to produce an
28 executable, regardless of the license terms of these independent
29 modules, and to copy and distribute the resulting executable under
30 terms of your choice, provided that you also meet, for each linked
31 independent module, the terms and conditions of the license of that
32 module. An independent module is a module which is not derived from
33 or based on this library. If you modify this library, you may extend
34 this exception to your version of the library, but you are not
35 obligated to do so. If you do not wish to do so, delete this
36 exception statement from your version. */
41 /* Written using "Java Class Libraries", 2nd edition, plus online
42 * API docs for JDK 1.2 from http://www.javasoft.com.
43 * Status: Believed complete and correct.
47 * This class represents a pre-computed series of bits representing a
48 * <code>String</code> for under a particular <code>Collator</code>. This
49 * value may be compared bitwise against another <code>CollationKey</code>
50 * representing a different <code>String</code> under the same
51 * <code>Collator</code> in a manner than is usually more efficient than
52 * using the raw <code>Collator</code> compare methods. There is overhead
53 * associated with calculating this value, so it is generally not
54 * advisable to compute <code>CollationKey</code>'s unless multiple
55 * comparisons against a <code>String</code> will be done. (For example,
58 * This class cannot be instantiated directly. Instead, a
59 * <code>CollationKey</code> is created by calling the
60 * <code>getCollationKey</code> method on an instance of <code>Collator</code>.
62 * @author Aaron M. Renn <arenn@urbanophile.com>
63 * @author Tom Tromey <tromey@cygnus.com>
64 * @date March 25, 1999
66 public final class CollationKey implements Comparable
69 * This is the <code>Collator</code> this object was created from.
71 private Collator collator;
74 * This is the <code>String</code> this object represents.
76 private String originalText;
79 * This is the bit value for this key.
83 CollationKey (Collator collator, String originalText, byte[] key)
85 this.collator = collator;
86 this.originalText = originalText;
91 * This method compares the specified object to this one. An integer is
92 * returned which indicates whether the specified object is less than,
93 * greater than, or equal to this object.
95 * @param ck The <code>CollationKey</code> to compare against this one.
97 * @return A negative integer if this object is less than the specified object, 0 if it is equal or a positive integer if it is greater than the specified object.
99 public int compareTo (CollationKey ck)
101 int max = Math.min (key.length, ck.key.length);
103 for (int i = 0; i < max; ++i)
105 if (key[i] != ck.key[i])
106 return key[i] - ck.key[i];
109 return key.length - ck.key.length;
113 * This method compares the specified object to this one. The specified
114 * object must be an instance of <code>CollationKey</code> or an exception
115 * will be thrown. An integer is returned which indicates whether the
116 * specified object is less than, greater than, or equal to this object.
118 * @param obj The <code>Object</code> to compare against this one.
120 * @return A negative integer if this object is less than the specified object, 0 if it is equal or a positive integer if it is greater than the specified object.
122 public int compareTo (Object obj)
124 return compareTo ((CollationKey) obj);
128 * This method tests the specified <code>Object</code> for equality with
129 * this object. This will be true if and only if:
132 * <li>The specified object must not be <code>null</code></li>
133 * <li>The specified object is an instance of <code>CollationKey</code>.</li>
134 * <li>The specified object was created from the same <code>Collator</code>
135 * as this object.</li>
136 * <li>The specified object has the same source string and bit key as
140 * @param obj The <code>Object</code> to test for equality.
142 * @return <code>true</code> if the specified object is equal to this one, <code>false</code> otherwise.
144 public boolean equals (Object obj)
146 if (! (obj instanceof CollationKey))
149 CollationKey ck = (CollationKey) obj;
151 if (ck.collator != collator)
154 if (!ck.getSourceString ().equals (getSourceString ()))
157 if (!ck.toByteArray ().equals (toByteArray ()))
164 * This method returns the <code>String</code> that this object was created
167 * @return The source <code>String</code> for this object.
169 public String getSourceString()
175 * This method returns a hash value for this object. The hash value
176 * returned will be the hash code of the bit key so that identical bit
177 * keys will return the same value.
179 * @return A hash value for this object.
181 public int hashCode()
183 // We just follow BitSet instead of thinking up something new.
184 long h = originalText.hashCode();
185 for (int i = key.length - 1; i >= 0; --i)
186 h ^= key[i] * (i + 1);
187 return (int) ((h >> 32) ^ h);
191 * This method returns the collation bit sequence as a byte array.
193 * @param A byte array containing the collation bit sequence.
195 public byte[] toByteArray()