/*
*
* @(#)CharacterIterator.java 1.22 06/10/10
*
* Portions Copyright 2000-2006 Sun Microsystems, Inc. All Rights
* Reserved. Use is subject to license terms.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License version
* 2 only, as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License version 2 for more details (a copy is
* included at /legal/license.txt).
*
* You should have received a copy of the GNU General Public License
* version 2 along with this work; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
* 02110-1301 USA
*
* Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa
* Clara, CA 95054 or visit www.sun.com if you need additional
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*/
/*
* (C) Copyright Taligent, Inc. 1996, 1997 - All Rights Reserved
* (C) Copyright IBM Corp. 1996 - 1998 - All Rights Reserved
*
* The original version of this source code and documentation
* is copyrighted and owned by Taligent, Inc., a wholly-owned
* subsidiary of IBM. These materials are provided under terms
* of a License Agreement between Taligent and Sun. This technology
* is protected by multiple US and International patents.
*
* This notice and attribution to Taligent may not be removed.
* Taligent is a registered trademark of Taligent, Inc.
*
*/
package java.text;
/**
* This interface defines a protocol for bidirectional iteration over text.
* The iterator iterates over a bounded sequence of characters. Characters
* are indexed with values beginning with the value returned by getBeginIndex() and
* continuing through the value returned by getEndIndex()-1.
* <p>
* Iterators maintain a current character index, whose valid range is from
* getBeginIndex() to getEndIndex(); the value getEndIndex() is included to allow
* handling of zero-length text ranges and for historical reasons.
* The current index can be retrieved by calling getIndex() and set directly
* by calling setIndex(), first(), and last().
* <p>
* The methods previous() and next() are used for iteration. They return DONE if
* they would move outside the range from getBeginIndex() to getEndIndex() -1,
* signaling that the iterator has reached the end of the sequence. DONE is
* also returned by other methods to indicate that the current index is
* outside this range.
*
* <P>Examples:<P>
*
* Traverse the text from start to finish
* <pre>
* public void traverseForward(CharacterIterator iter) {
* for(char c = iter.first(); c != CharacterIterator.DONE; c = iter.next()) {
* processChar(c);
* }
* }
* </pre>
*
* Traverse the text backwards, from end to start
* <pre>
* public void traverseBackward(CharacterIterator iter) {
* for(char c = iter.last(); c != CharacterIterator.DONE; c = iter.previous()) {
* processChar(c);
* }
* }
* </pre>
*
* Traverse both forward and backward from a given position in the text.
* Calls to notBoundary() in this example represents some
* additional stopping criteria.
* <pre>
* public void traverseOut(CharacterIterator iter, int pos) {
* for (char c = iter.setIndex(pos);
* c != CharacterIterator.DONE && notBoundary(c);
* c = iter.next()) {
* }
* int end = iter.getIndex();
* for (char c = iter.setIndex(pos);
* c != CharacterIterator.DONE && notBoundary(c);
* c = iter.previous()) {
* }
* int start = iter.getIndex();
* processSection(start, end);
* }
* </pre>
*
* @see StringCharacterIterator
* @see AttributedCharacterIterator
*/
public interface CharacterIterator extends Cloneable
{
/**
* Constant that is returned when the iterator has reached either the end
* or the beginning of the text. The value is '\\uFFFF', the "not a
* character" value which should not occur in any valid Unicode string.
*/
public static final char DONE = '\uFFFF';
/**
* Sets the position to getBeginIndex() and returns the character at that
* position.
* @return the first character in the text, or DONE if the text is empty
* @see #getBeginIndex()
*/
public char first();
/**
* Sets the position to getEndIndex()-1 (getEndIndex() if the text is empty)
* and returns the character at that position.
* @return the last character in the text, or DONE if the text is empty
* @see #getEndIndex()
*/
public char last();
/**
* Gets the character at the current position (as returned by getIndex()).
* @return the character at the current position or DONE if the current
* position is off the end of the text.
* @see #getIndex()
*/
public char current();
/**
* Increments the iterator's index by one and returns the character
* at the new index. If the resulting index is greater or equal
* to getEndIndex(), the current index is reset to getEndIndex() and
* a value of DONE is returned.
* @return the character at the new position or DONE if the new
* position is off the end of the text range.
*/
public char next();
/**
* Decrements the iterator's index by one and returns the character
* at the new index. If the current index is getBeginIndex(), the index
* remains at getBeginIndex() and a value of DONE is returned.
* @return the character at the new position or DONE if the current
* position is equal to getBeginIndex().
*/
public char previous();
/**
* Sets the position to the specified position in the text and returns that
* character.
* @param position the position within the text. Valid values range from
* getBeginIndex() to getEndIndex(). An IllegalArgumentException is thrown
* if an invalid value is supplied.
* @return the character at the specified position or DONE if the specified position is equal to getEndIndex()
*/
public char setIndex(int position);
/**
* Returns the start index of the text.
* @return the index at which the text begins.
*/
public int getBeginIndex();
/**
* Returns the end index of the text. This index is the index of the first
* character following the end of the text.
* @return the index after the last character in the text
*/
public int getEndIndex();
/**
* Returns the current index.
* @return the current index.
*/
public int getIndex();
/**
* Create a copy of this iterator
* @return A copy of this
*/
public Object clone();
}
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