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356 lines
10 KiB
Java
356 lines
10 KiB
Java
/* BreakIterator.java -- Breaks text into elements
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Copyright (C) 1998, 1999, 2001 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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import java.util.Locale;
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import java.util.MissingResourceException;
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import java.util.ResourceBundle;
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/**
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* This class iterates over text elements such as words, lines, sentences,
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* and characters. It can only iterate over one of these text elements at
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* a time. An instance of this class configured for the desired iteration
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* type is created by calling one of the static factory methods, not
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* by directly calling a constructor.
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*
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* @author Tom Tromey <tromey@cygnus.com>
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* @author Aaron M. Renn (arenn@urbanophile.com)
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* @date March 19, 1999
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*/
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/* Written using "Java Class Libraries", 2nd edition, plus online
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* API docs for JDK 1.2 beta from http://www.javasoft.com.
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* Status: Believed complete and correct to 1.1.
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*/
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public abstract class BreakIterator implements Cloneable
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{
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/**
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* This value is returned by the <code>next()</code> and
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* <code>previous</code> in order to indicate that the end of the
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* text has been reached.
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*/
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// The value was discovered by writing a test program.
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public static final int DONE = -1;
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/**
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* This method initializes a new instance of <code>BreakIterator</code>.
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* This protected constructor is available to subclasses as a default
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* no-arg superclass constructor.
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*/
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protected BreakIterator ()
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{
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}
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/**
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* This method returns the index of the current text element boundary.
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*
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* @return The current text boundary.
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*/
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public abstract int current ();
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/**
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* This method returns the first text element boundary in the text being
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* iterated over.
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*
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* @return The first text boundary.
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*/
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public abstract int first ();
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/**
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* This methdod returns the offset of the text element boundary following
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* the specified offset.
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*
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* @param offset The text index from which to find the next text boundary.
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*
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* @param The next text boundary following the specified index.
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*/
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public abstract int following (int pos);
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/**
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* This method returns a list of locales for which instances of
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* <code>BreakIterator</code> are available.
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*
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* @return A list of available locales
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*/
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public static synchronized Locale[] getAvailableLocales ()
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{
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Locale[] l = new Locale[1];
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l[0] = Locale.US;
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return l;
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}
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private static BreakIterator getInstance (String type, Locale loc)
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{
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String className;
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try
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{
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ResourceBundle res
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= ResourceBundle.getBundle("gnu.java.locale.LocaleInformation",
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loc);
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className = res.getString(type);
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}
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catch (MissingResourceException x)
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{
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return null;
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}
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try
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{
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Class k = Class.forName(className);
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return (BreakIterator) k.newInstance();
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}
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catch (ClassNotFoundException x1)
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{
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return null;
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}
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catch (InstantiationException x2)
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{
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return null;
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}
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catch (IllegalAccessException x3)
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{
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return null;
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}
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}
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/**
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* This method returns an instance of <code>BreakIterator</code> that will
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* iterate over characters as defined in the default locale.
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*
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* @return A <code>BreakIterator</code> instance for the default locale.
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*/
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public static BreakIterator getCharacterInstance ()
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{
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return getCharacterInstance (Locale.getDefault());
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}
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/**
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* This method returns an instance of <code>BreakIterator</code> that will
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* iterate over characters as defined in the specified locale. If the
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* desired locale is not available, the default locale is used.
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*
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* @param locale The desired locale.
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*
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* @return A <code>BreakIterator</code> instance for the default locale.
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*/
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public static BreakIterator getCharacterInstance (Locale loc)
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{
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BreakIterator r = getInstance ("CharacterIterator", loc);
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if (r == null)
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r = new gnu.java.text.CharacterBreakIterator ();
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return r;
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}
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/**
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* This method returns an instance of <code>BreakIterator</code> that will
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* iterate over line breaks as defined in the default locale.
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*
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* @return A <code>BreakIterator</code> instance for the default locale.
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*/
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public static BreakIterator getLineInstance ()
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{
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return getLineInstance (Locale.getDefault());
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}
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/**
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* This method returns an instance of <code>BreakIterator</code> that will
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* iterate over line breaks as defined in the specified locale. If the
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* desired locale is not available, the default locale is used.
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*
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* @param locale The desired locale.
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*
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* @return A <code>BreakIterator</code> instance for the default locale.
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*/
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public static BreakIterator getLineInstance (Locale loc)
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{
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BreakIterator r = getInstance ("LineIterator", loc);
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if (r == null)
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r = new gnu.java.text.LineBreakIterator ();
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return r;
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}
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/**
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* This method returns an instance of <code>BreakIterator</code> that will
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* iterate over sentences as defined in the default locale.
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*
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* @return A <code>BreakIterator</code> instance for the default locale.
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*/
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public static BreakIterator getSentenceInstance ()
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{
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return getSentenceInstance (Locale.getDefault());
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}
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/**
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* This method returns an instance of <code>BreakIterator</code> that will
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* iterate over sentences as defined in the specified locale. If the
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* desired locale is not available, the default locale is used.
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*
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* @param locale The desired locale.
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*
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* @return A <code>BreakIterator</code> instance for the default locale.
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*/
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public static BreakIterator getSentenceInstance (Locale loc)
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{
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BreakIterator r = getInstance ("SentenceIterator", loc);
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if (r == null)
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r = new gnu.java.text.SentenceBreakIterator ();
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return r;
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}
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/**
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* This method returns the text this object is iterating over as a
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* <code>CharacterIterator</code>.
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*
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* @param The text being iterated over.
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*/
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public abstract CharacterIterator getText ();
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/**
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* This method returns an instance of <code>BreakIterator</code> that will
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* iterate over words as defined in the default locale.
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*
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* @return A <code>BreakIterator</code> instance for the default locale.
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*/
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public static BreakIterator getWordInstance ()
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{
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return getWordInstance (Locale.getDefault());
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}
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/**
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* This method returns an instance of <code>BreakIterator</code> that will
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* iterate over words as defined in the specified locale. If the
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* desired locale is not available, the default locale is used.
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*
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* @param locale The desired locale.
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*
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* @return A <code>BreakIterator</code> instance for the default locale.
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*/
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public static BreakIterator getWordInstance (Locale loc)
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{
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BreakIterator r = getInstance ("WordIterator", loc);
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if (r == null)
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r = new gnu.java.text.WordBreakIterator ();
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return r;
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}
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/**
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* This method tests whether or not the specified position is a text
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* element boundary.
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*
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* @param offset The text position to test.
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*
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* @return <code>true</code> if the position is a boundary,
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* <code>false</code> otherwise.
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*/
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public boolean isBoundary (int pos)
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{
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if (pos == 0)
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return true;
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return following (pos - 1) == pos;
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}
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/**
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* This method returns the last text element boundary in the text being
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* iterated over.
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*
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* @return The last text boundary.
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*/
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public abstract int last ();
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/**
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* This method returns the text element boundary following the current
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* text position.
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*
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* @return The next text boundary.
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*/
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public abstract int next ();
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/**
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* This method returns the n'th text element boundary following the current
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* text position.
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*
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* @param n The number of text element boundaries to skip.
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*
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* @return The next text boundary.
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*/
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public abstract int next (int n);
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/**
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* This methdod returns the offset of the text element boundary preceding
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* the specified offset.
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*
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* @param offset The text index from which to find the preceding
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* text boundary.
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*
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* @returns The next text boundary preceding the specified index.
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*/
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public int preceding (int pos)
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{
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if (following (pos) == DONE)
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last ();
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while (previous () >= pos)
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;
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return current ();
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}
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/**
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* This method returns the text element boundary preceding the current
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* text position.
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*
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* @return The previous text boundary.
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*/
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public abstract int previous ();
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/**
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* This method sets the text string to iterate over.
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*
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* @param str The <code>String</code> to iterate over.
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*/
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public void setText (String newText)
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{
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setText (new StringCharacterIterator (newText));
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}
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/**
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* This method sets the text to iterate over from the specified
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* <code>CharacterIterator</code>.
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*
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* @param ci The desired <code>CharacterIterator</code>.
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*/
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public abstract void setText (CharacterIterator newText);
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}
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