200 lines
6.7 KiB
Java
200 lines
6.7 KiB
Java
/* CollationKey.java -- Precomputed collation value
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Copyright (C) 1998, 1999, 2000, 2003 Free Software Foundation, Inc.
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This file is part of GNU Classpath.
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GNU Classpath is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2, or (at your option)
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any later version.
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GNU Classpath is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with GNU Classpath; see the file COPYING. If not, write to the
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Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
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02111-1307 USA.
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Linking this library statically or dynamically with other modules is
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making a combined work based on this library. Thus, the terms and
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conditions of the GNU General Public License cover the whole
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combination.
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As a special exception, the copyright holders of this library give you
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permission to link this library with independent modules to produce an
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executable, regardless of the license terms of these independent
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modules, and to copy and distribute the resulting executable under
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terms of your choice, provided that you also meet, for each linked
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independent module, the terms and conditions of the license of that
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module. An independent module is a module which is not derived from
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or based on this library. If you modify this library, you may extend
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this exception to your version of the library, but you are not
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obligated to do so. If you do not wish to do so, delete this
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exception statement from your version. */
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package java.text;
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/* Written using "Java Class Libraries", 2nd edition, plus online
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* API docs for JDK 1.2 from http://www.javasoft.com.
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* Status: Believed complete and correct.
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*/
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/**
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* This class represents a pre-computed series of bits representing a
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* <code>String</code> for under a particular <code>Collator</code>. This
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* value may be compared bitwise against another <code>CollationKey</code>
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* representing a different <code>String</code> under the same
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* <code>Collator</code> in a manner than is usually more efficient than
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* using the raw <code>Collator</code> compare methods. There is overhead
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* associated with calculating this value, so it is generally not
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* advisable to compute <code>CollationKey</code>'s unless multiple
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* comparisons against a <code>String</code> will be done. (For example,
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* in a sort routine).
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* <p>
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* This class cannot be instantiated directly. Instead, a
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* <code>CollationKey</code> is created by calling the
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* <code>getCollationKey</code> method on an instance of <code>Collator</code>.
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*
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* @author Aaron M. Renn <arenn@urbanophile.com>
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* @author Tom Tromey <tromey@cygnus.com>
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* @date March 25, 1999
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*/
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public final class CollationKey implements Comparable
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{
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/**
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* This is the <code>Collator</code> this object was created from.
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*/
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private Collator collator;
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/**
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* This is the <code>String</code> this object represents.
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*/
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private String originalText;
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/**
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* This is the bit value for this key.
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*/
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private byte[] key;
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CollationKey (Collator collator, String originalText, byte[] key)
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{
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this.collator = collator;
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this.originalText = originalText;
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this.key = key;
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}
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/**
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* This method compares the specified object to this one. An integer is
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* returned which indicates whether the specified object is less than,
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* greater than, or equal to this object.
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*
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* @param ck The <code>CollationKey</code> to compare against this one.
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*
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* @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.
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*/
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public int compareTo (CollationKey ck)
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{
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int max = Math.min (key.length, ck.key.length);
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for (int i = 0; i < max; ++i)
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{
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if (key[i] != ck.key[i])
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return key[i] - ck.key[i];
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}
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return key.length - ck.key.length;
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}
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/**
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* This method compares the specified object to this one. The specified
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* object must be an instance of <code>CollationKey</code> or an exception
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* will be thrown. An integer is returned which indicates whether the
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* specified object is less than, greater than, or equal to this object.
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*
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* @param obj The <code>Object</code> to compare against this one.
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*
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* @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.
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*/
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public int compareTo (Object obj)
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{
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return compareTo ((CollationKey) obj);
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}
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/**
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* This method tests the specified <code>Object</code> for equality with
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* this object. This will be true if and only if:
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* <p>
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* <ul>
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* <li>The specified object must not be <code>null</code></li>
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* <li>The specified object is an instance of <code>CollationKey</code>.</li>
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* <li>The specified object was created from the same <code>Collator</code>
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* as this object.</li>
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* <li>The specified object has the same source string and bit key as
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* this object.</li>
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* </ul>
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*
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* @param obj The <code>Object</code> to test for equality.
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*
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* @return <code>true</code> if the specified object is equal to this one, <code>false</code> otherwise.
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*/
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public boolean equals (Object obj)
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{
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if (! (obj instanceof CollationKey))
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return false;
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CollationKey ck = (CollationKey) obj;
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if (ck.collator != collator)
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return false;
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if (!ck.getSourceString ().equals (getSourceString ()))
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return false;
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if (!ck.toByteArray ().equals (toByteArray ()))
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return false;
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return true;
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}
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/**
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* This method returns the <code>String</code> that this object was created
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* from.
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*
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* @return The source <code>String</code> for this object.
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*/
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public String getSourceString()
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{
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return originalText;
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}
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/**
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* This method returns a hash value for this object. The hash value
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* returned will be the hash code of the bit key so that identical bit
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* keys will return the same value.
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*
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* @return A hash value for this object.
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*/
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public int hashCode()
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{
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// We just follow BitSet instead of thinking up something new.
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long h = originalText.hashCode();
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for (int i = key.length - 1; i >= 0; --i)
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h ^= key[i] * (i + 1);
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return (int) ((h >> 32) ^ h);
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}
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/**
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* This method returns the collation bit sequence as a byte array.
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*
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* @param A byte array containing the collation bit sequence.
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*/
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public byte[] toByteArray()
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{
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return key;
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}
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}
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