001/* CharacterIterator.java -- Iterate over a character range
002   Copyright (C) 1998, 2001, 2005 Free Software Foundation, Inc.
003
004This file is part of GNU Classpath.
005
006GNU Classpath is free software; you can redistribute it and/or modify
007it under the terms of the GNU General Public License as published by
008the Free Software Foundation; either version 2, or (at your option)
009any later version.
010
011GNU Classpath is distributed in the hope that it will be useful, but
012WITHOUT ANY WARRANTY; without even the implied warranty of
013MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
014General Public License for more details.
015
016You should have received a copy of the GNU General Public License
017along with GNU Classpath; see the file COPYING.  If not, write to the
018Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
01902110-1301 USA.
020
021Linking this library statically or dynamically with other modules is
022making a combined work based on this library.  Thus, the terms and
023conditions of the GNU General Public License cover the whole
024combination.
025
026As a special exception, the copyright holders of this library give you
027permission to link this library with independent modules to produce an
028executable, regardless of the license terms of these independent
029modules, and to copy and distribute the resulting executable under
030terms of your choice, provided that you also meet, for each linked
031independent module, the terms and conditions of the license of that
032module.  An independent module is a module which is not derived from
033or based on this library.  If you modify this library, you may extend
034this exception to your version of the library, but you are not
035obligated to do so.  If you do not wish to do so, delete this
036exception statement from your version. */
037
038
039package java.text;
040
041/**
042  * This interface defines a mechanism for iterating over a range of
043  * characters.  For a given range of text, a beginning and ending index,
044  * as well as a current index are defined.  These values can be queried
045  * by the methods in this interface.  Additionally, various methods allow
046  * the index to be set.
047  *
048  * @author Aaron M. Renn (arenn@urbanophile.com)
049  */
050public interface CharacterIterator extends Cloneable
051{
052  /**
053   * This is a special constant value that is returned when the beginning or
054   * end of the character range has been reached.
055   */
056  char DONE = '\uFFFF';
057
058  /**
059   * This method returns the character at the current index position
060   *
061   * @return The character at the current index position.
062   */
063  char current();
064
065  /**
066   * This method increments the current index and then returns the character
067   * at the new index value.  If the index is already at
068   * <code>getEndIndex() - 1</code>, it will not be incremented.
069   *
070   * @return The character at the position of the incremented index value,
071   * or {@link #DONE} if the index has reached getEndIndex() - 1
072   */
073  char next();
074
075  /**
076   * This method decrements the current index and then returns the character
077   * at the new index value.  If the index value is already at the beginning
078   * index, it will not be decremented.
079   *
080   * @return The character at the position of the decremented index value,
081   *         or {@link #DONE} if index was already equal to the beginning index
082   *         value.
083   */
084  char previous();
085
086  /**
087   * This method sets the index value to the beginning of the range and returns
088   * the character there.
089   *
090   * @return The character at the beginning of the range, or {@link #DONE} if
091   *         the range is empty.
092   */
093  char first();
094
095  /**
096   * This method sets the index value to <code>getEndIndex() - 1</code> and
097   * returns the character there.  If the range is empty, then the index value
098   * will be set equal to the beginning index.
099   *
100   * @return The character at the end of the range, or {@link #DONE} if the
101   *         range is empty.
102   */
103  char last();
104
105  /**
106   * This method returns the current value of the index.
107   *
108   * @return The current index value
109   */
110  int getIndex();
111
112  /**
113   * This method sets the value of the index to the specified value, then
114   * returns the character at that position.
115   *
116   * @param index The new index value.
117   *
118   * @return The character at the new index value or {@link #DONE} if the index
119   *         value is equal to {@link #getEndIndex()}.
120   */
121  char setIndex (int index) throws IllegalArgumentException;
122
123  /**
124   * This method returns the character position of the first character in the
125   * range.
126   *
127   * @return The index of the first character in the range.
128   */
129  int getBeginIndex();
130
131  /**
132   * This method returns the character position of the end of the text range.
133   * This will actually be the index of the first character following the
134   * end of the range.  In the event the text range is empty, this will be
135   * equal to the first character in the range.
136   *
137   * @return The index of the end of the range.
138   */
139  int getEndIndex();
140
141  /**
142   * This method creates a copy of this <code>CharacterIterator</code>.
143   *
144   * @return A copy of this <code>CharacterIterator</code>.
145   */
146  Object clone();
147
148} // interface CharacterIterator