/*
 * Copyright (c) 1996, 2013, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 *
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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>{@code
 * 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>{@code
 * 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>{@code
 * 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();

}