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   * Copyright (c) 1996, 2013, Oracle and/or its affiliates. All rights reserved.
   * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   *
   * This code 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.  Oracle designates this
   * particular file as subject to the "Classpath" exception as provided
   * by Oracle in the LICENSE file that accompanied this code.
   *
   * This code 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 in the LICENSE file that
   * accompanied this code).
   *
   * 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
   * or visit www.oracle.com if you need additional information or have any
   * questions.
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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();
  
  }
  