libjava/java/text/CollationElementIterator.java

   1 /* CollationElementIterator.java -- Walks through collation elements
   2    Copyright (C) 1998, 1999, 2001, 2002, 2003  Free Software Foundation
   3
   4 This file is part of GNU Classpath.
   5
   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)
   9 any later version.
  10
  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.
  15
  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
  19 02111-1307 USA.
  20
  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
  24 combination.
  25
  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. */
  37
  38
  39 package java.text;
  40
  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 to JDK 1.1.
  44  */
  45
  46 /**
  47  * This class walks through the character collation elements of a
  48  * <code>String</code> as defined by the collation rules in an instance of
  49  * <code>RuleBasedCollator</code>.  There is no public constructor for
  50  * this class.  An instance is created by calling the
  51  * <code>getCollationElementIterator</code> method on
  52  * <code>RuleBasedCollator</code>.
  53  *
  54  * @author Aaron M. Renn <arenn@urbanophile.com>
  55  * @author Tom Tromey <tromey@cygnus.com>
  56  */
  57 public final class CollationElementIterator
  58 {
  59   /**
  60    * This is a constant value that is returned to indicate that the end of
  61    * the string was encountered.
  62    */
  63   public static final int NULLORDER = -1;
  64
  65   /**
  66    * This is the RuleBasedCollator this object was created from.
  67    */
  68   RuleBasedCollator collator;
  69
  70   /**
  71    * This is the String that is being iterated over.
  72    */
  73   String text;
  74
  75   /**
  76    * This is the index into the String where we are currently scanning.
  77    */
  78   int index;
  79
  80   // A piece of lookahead.
  81   boolean lookahead_set;
  82   int lookahead;
  83
  84   /**
  85    * This method returns the collation ordering value of the next character
  86    * in the string.  This method will return <code>NULLORDER</code> if the
  87    * end of the string was reached.
  88    *
  89    * @return The collation ordering value.
  90    */
  91   public int next ()
  92   {
  93     if (index == text.length())
  94       return NULLORDER;
  95
  96     return collator.ceiNext(this);
  97   }
  98
  99   /**
 100    * This method returns the primary order value for the given collation
 101    * value.
 102    *
 103    * @param value The collation value returned from <code>next()</code> or <code>previous()</code>.
 104    *
 105    * @return The primary order value of the specified collation value.  This is the high 16 bits.
 106    */
 107   public static final int primaryOrder (int order)
 108   {
 109     // From the JDK 1.2 spec.
 110     return order >>> 16;
 111   }
 112
 113   /**
 114    * This method resets the internal position pointer to read from the
 115    * beginning of the <code>String again.
 116    */
 117   public void reset ()
 118   {
 119     index = 0;
 120   }
 121
 122   /**
 123    * This method returns the secondary order value for the given collation
 124    * value.
 125    *
 126    * @param value The collation value returned from <code>next()</code> or <code>previous()</code>.
 127    *
 128    * @return The secondary order value of the specified collation value.  This is the bits 8-15.
 129    */
 130   public static final short secondaryOrder (int order)
 131   {
 132     // From the JDK 1.2 spec.
 133     return (short) ((order >>> 8) & 255);
 134   }
 135
 136   /**
 137    * This method returns the tertiary order value for the given collation
 138    * value.
 139    *
 140    * @param value The collation value returned from <code>next()</code> or <code>previous()</code>.
 141    *
 142    * @return The tertiary order value of the specified collation value.  This is the low eight bits.
 143    */
 144   public static final short tertiaryOrder (int order)
 145   {
 146     // From the JDK 1.2 spec.
 147     return (short) (order & 255);
 148   }
 149
 150   // Non-public constructor.
 151   CollationElementIterator (String text, RuleBasedCollator collator)
 152   {
 153     this.text = text;
 154     this.index = 0;
 155     this.lookahead_set = false;
 156     this.lookahead = 0;
 157     this.collator = collator;
 158   }
 159
 160 } // class CollationElementIterator
 161