1 /*
   2  * Copyright (c) 2009, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.  Oracle designates this
   8  * particular file as subject to the "Classpath" exception as provided
   9  * by Oracle in the LICENSE file that accompanied this code.
  10  *
  11  * This code is distributed in the hope that it will be useful, but WITHOUT
  12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14  * version 2 for more details (a copy is included in the LICENSE file that
  15  * accompanied this code).
  16  *
  17  * You should have received a copy of the GNU General Public License version
  18  * 2 along with this work; if not, write to the Free Software Foundation,
  19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  20  *
  21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  22  * or visit www.oracle.com if you need additional information or have any
  23  * questions.
  24  */
  25 /*
  26  *******************************************************************************
  27  * (C) Copyright IBM Corp. and others, 1996-2009 - All Rights Reserved         *
  28  *                                                                             *
  29  * The original version of this source code and documentation is copyrighted   *
  30  * and owned by IBM, These materials are provided under terms of a License     *
  31  * Agreement between IBM and Sun. This technology is protected by multiple     *
  32  * US and International patents. This notice and attribution to IBM may not    *
  33  * to removed.                                                                 *
  34  *******************************************************************************
  35  */
  36 /* Written by Simon Montagu, Matitiahu Allouche
  37  * (ported from C code written by Markus W. Scherer)
  38  */
  39 
  40 package sun.text.bidi;
  41 
  42 /**
  43  * A BidiRun represents a sequence of characters at the same embedding level.
  44  * The Bidi algorithm decomposes a piece of text into sequences of characters
  45  * at the same embedding level, each such sequence is called a "run".
  46  *
  47  * <p>A BidiRun represents such a run by storing its essential properties,
  48  * but does not duplicate the characters which form the run.
  49  *
  50  * <p>The &quot;limit&quot; of the run is the position just after the
  51  * last character, i.e., one more than that position.
  52  *
  53  * <p>This class has no public constructor, and its members cannot be
  54  * modified by users.
  55  *
  56  * @see com.ibm.icu.text.Bidi
  57  */
  58 public class BidiRun {
  59 
  60     int start;              /* first logical position of the run */
  61     int limit;              /* last visual position of the run +1 */
  62     int insertRemove;       /* if >0, flags for inserting LRM/RLM before/after run,
  63                                if <0, count of bidi controls within run            */
  64     byte level;
  65 
  66     /*
  67      * Default constructor
  68      *
  69      * Note that members start and limit of a run instance have different
  70      * meanings depending whether the run is part of the runs array of a Bidi
  71      * object, or if it is a reference returned by getVisualRun() or
  72      * getLogicalRun().
  73      * For a member of the runs array of a Bidi object,
  74      *   - start is the first logical position of the run in the source text.
  75      *   - limit is one after the last visual position of the run.
  76      * For a reference returned by getLogicalRun() or getVisualRun(),
  77      *   - start is the first logical position of the run in the source text.
  78      *   - limit is one after the last logical position of the run.
  79      */
  80     BidiRun()
  81     {
  82         this(0, 0, (byte)0);
  83     }
  84 
  85     /*
  86      * Constructor
  87      */
  88     BidiRun(int start, int limit, byte embeddingLevel)
  89     {
  90         this.start = start;
  91         this.limit = limit;
  92         this.level = embeddingLevel;
  93     }
  94 
  95     /*
  96      * Copy the content of a BidiRun instance
  97      */
  98     void copyFrom(BidiRun run)
  99     {
 100         this.start = run.start;
 101         this.limit = run.limit;
 102         this.level = run.level;
 103         this.insertRemove = run.insertRemove;
 104     }
 105 
 106     /**
 107      * Get level of run
 108      */
 109     public byte getEmbeddingLevel()
 110     {
 111         return level;
 112     }
 113 
 114     /**
 115      * Check if run level is even
 116      * @return true if the embedding level of this run is even, i.e. it is a
 117      *  left-to-right run.
 118      */
 119     boolean isEvenRun()
 120     {
 121         return (level & 1) == 0;
 122     }
 123 
 124 }