357 lines
11 KiB
Java
357 lines
11 KiB
Java
/* StringCharacterIterator.java -- Iterate over a character range in a string
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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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/**
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* This class iterates over a range of characters in a <code>String</code>.
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* For a given range of text, a beginning and ending index,
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* as well as a current index are defined. These values can be queried
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* by the methods in this interface. Additionally, various methods allow
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* the index to be set.
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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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*/
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public final class StringCharacterIterator implements CharacterIterator
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{
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/**
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* This is the string to iterate over
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*/
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private String text;
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/**
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* This is the value of the start position of the text range.
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*/
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private int begin;
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/**
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* This is the value of the ending position of the text range.
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*/
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private int end;
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/**
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* This is the current value of the scan index.
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*/
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private int index;
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/**
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* This method initializes a new instance of
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* <code>StringCharacterIterator</code> to iterate over the entire
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* text of the specified <code>String</code>. The initial index
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* value will be set to the first character in the string.
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*
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* @param text The <code>String</code> to iterate through.
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*/
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public StringCharacterIterator (String text)
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{
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this (text, 0, text.length (), 0);
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}
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/*************************************************************************/
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/**
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* This method initializes a new instance of
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* <code>StringCharacterIterator</code> to iterate over the entire
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* text of the specified <code>String</code>. The initial index
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* value will be set to the specified value.
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*
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* @param text The <code>String</code> to iterate through.
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* @param index The initial index position.
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*/
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public StringCharacterIterator (String text, int index)
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{
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this (text, 0, text.length (), index);
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}
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/*************************************************************************/
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/**
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* This method initializes a new instance of
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* <code>StringCharacterIterator</code> that iterates over the text
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* in a subrange of the specified <code>String</code>. The
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* beginning and end of the range are specified by the caller, as is
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* the initial index position.
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*
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* @param text The <code>String</code> to iterate through.
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* @param begin The beginning position in the character range.
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* @param end The ending position in the character range.
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* @param index The initial index position.
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*
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* @param IllegalArgumentException If any of the range values are
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* invalid.
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*/
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public StringCharacterIterator (String text, int begin, int end, int index)
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{
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int len = text.length ();
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if ((begin < 0) || (begin > len))
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throw new IllegalArgumentException ("Bad begin position");
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if ((end < begin) || (end > len))
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throw new IllegalArgumentException ("Bad end position");
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if ((index < begin) || (index > end))
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throw new IllegalArgumentException ("Bad initial index position");
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this.text = text;
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this.begin = begin;
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this.end = end;
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this.index = index;
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}
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/**
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* This is a package level constructor that copies the text out of
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* an existing StringCharacterIterator and resets the beginning and
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* ending index.
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*
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* @param scci The StringCharacterIterator to copy the info from
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* @param begin The beginning index of the range we are interested in.
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* @param end The ending index of the range we are interested in.
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*/
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StringCharacterIterator (StringCharacterIterator sci, int begin, int end)
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{
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this (sci.text, begin, end, begin);
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}
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/**
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* This method returns the character at the current index position
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*
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* @return The character at the current index position.
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*/
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public char current ()
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{
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return (index < end) ? text.charAt (index) : DONE;
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}
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/*************************************************************************/
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/**
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* This method increments the current index and then returns the
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* character at the new index value. If the index is already at
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* <code>getEndIndex () - 1</code>, it will not be incremented.
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*
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* @return The character at the position of the incremented index
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* value, or <code>DONE</code> if the index has reached
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* getEndIndex () - 1.
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*/
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public char next ()
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{
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if (index == end)
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return DONE;
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++index;
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return current ();
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}
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/*************************************************************************/
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/**
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* This method decrements the current index and then returns the
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* character at the new index value. If the index value is already
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* at the beginning index, it will not be decremented.
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*
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* @return The character at the position of the decremented index
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* value, or <code>DONE</code> if index was already equal to the
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* beginning index value.
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*/
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public char previous ()
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{
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if (index == begin)
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return DONE;
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--index;
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return current ();
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}
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/*************************************************************************/
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/**
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* This method sets the index value to the beginning of the range and returns
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* the character there.
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*
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* @return The character at the beginning of the range, or
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* <code>DONE</code> if the range is empty.
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*/
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public char first ()
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{
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index = begin;
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return current ();
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}
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/*************************************************************************/
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/**
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* This method sets the index value to <code>getEndIndex () - 1</code> and
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* returns the character there. If the range is empty, then the index value
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* will be set equal to the beginning index.
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*
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* @return The character at the end of the range, or
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* <code>DONE</code> if the range is empty.
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*/
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public char last ()
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{
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if (end == begin)
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return DONE;
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index = end - 1;
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return current ();
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}
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/*************************************************************************/
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/**
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* This method returns the current value of the index.
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*
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* @return The current index value
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*/
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public int getIndex ()
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{
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return index;
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}
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/*************************************************************************/
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/**
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* This method sets the value of the index to the specified value, then
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* returns the character at that position.
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*
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* @param index The new index value.
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*
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* @return The character at the new index value or <code>DONE</code>
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* if the index value is equal to <code>getEndIndex</code>.
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*
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* @exception IllegalArgumentException If the specified index is not valid
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*/
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public char setIndex (int index)
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{
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if ((index < begin) || (index > end))
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throw new IllegalArgumentException ("Bad index specified");
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this.index = index;
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return current ();
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}
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/*************************************************************************/
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/**
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* This method returns the character position of the first character in the
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* range.
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*
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* @return The index of the first character in the range.
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*/
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public int getBeginIndex ()
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{
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return begin;
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}
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/*************************************************************************/
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/**
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* This method returns the character position of the end of the text range.
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* This will actually be the index of the first character following the
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* end of the range. In the event the text range is empty, this will be
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* equal to the first character in the range.
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*
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* @return The index of the end of the range.
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*/
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public int getEndIndex ()
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{
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return end;
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}
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/*************************************************************************/
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/**
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* This method creates a copy of this <code>CharacterIterator</code>.
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*
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* @return A copy of this <code>CharacterIterator</code>.
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*/
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public Object clone ()
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{
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return new StringCharacterIterator (text, begin, end, index);
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}
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/*************************************************************************/
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/**
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* This method tests this object for equality againt the specified
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* object. This will be true if and only if the specified object:
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* <p>
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* <ul>
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* <li>is not <code>null</code>.
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* <li>is an instance of <code>StringCharacterIterator</code>
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* <li>has the same text as this object
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* <li>has the same beginning, ending, and current index as this object.
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* </ul>
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*
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* @param obj The object to test for equality against.
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*
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* @return <code>true</code> if the specified object is equal to this
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* object, <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 StringCharacterIterator))
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return false;
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StringCharacterIterator sci = (StringCharacterIterator) obj;
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return (begin == sci.begin
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&& end == sci.end
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&& index == sci.index
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&& text.equals (sci.text));
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}
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/*************************************************************************/
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/**
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* This method allows other classes in java.text to change the value
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* of the underlying text being iterated through.
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*
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* @param text The new <code>String</code> to iterate through.
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*/
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public void setText (String text)
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{
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this.text = text;
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this.begin = 0;
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this.end = text.length ();
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this.index = 0;
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}
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}
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