libjava/gnu/java/text/LineBreakIterator.java

/* LineBreakIterator.java - Default word BreakIterator.
   Copyright (C) 1999, 2001 Free Software Foundation, Inc.

This file is part of GNU Classpath.

GNU Classpath is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2, or (at your option)
any later version.
 
GNU Classpath 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 for more details.

You should have received a copy of the GNU General Public License
along with GNU Classpath; see the file COPYING.  If not, write to the
Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
02111-1307 USA.

As a special exception, if you link this library with other files to
produce an executable, this library does not by itself cause the
resulting executable to be covered by the GNU General Public License.
This exception does not however invalidate any other reasons why the
executable file might be covered by the GNU General Public License. */


package gnu.java.text;

import java.text.BreakIterator;
import java.text.CharacterIterator;

/**
 * @author Tom Tromey <tromey@cygnus.com>
 * @date March 22, 1999
 * Written using The Unicode Standard, Version 2.0.
 */

public class LineBreakIterator extends BaseBreakIterator
{
  public Object clone ()
  {
    return new LineBreakIterator (this);
  }

  public LineBreakIterator ()
  {
    iter = null;
  }

  private LineBreakIterator (LineBreakIterator other)
  {
    iter = (CharacterIterator) other.iter.clone();
  }

  // Some methods to tell us different properties of characters.
  private final boolean isNb (char c)
  {
    return (c == 0x00a0		// NO-BREAK SPACE
	    || c == 0x2011	// NON-BREAKING HYPHEN
	    || c == 0xfeff);	// ZERO WITH NO-BREAK SPACE
  }
  private final boolean isClose (int type)
  {
    return (type == Character.END_PUNCTUATION
	    // Unicode book says "comma, period, ...", which I take to
	    // mean "Po" class.
	    || type == Character.OTHER_PUNCTUATION);
  }
  private final boolean isIdeo (char c)
  {
    return (c >= 0x3040 && c <= 0x309f	       // Hiragana
	    || c >= 0x30a0 && c <= 0x30ff      // Katakana
	    || c >= 0x4e00 && c <= 0x9fff      // Han
	    || c >= 0x3100 && c <= 0x312f);    // Bopomofo
  }

  public int next ()
  {
    int end = iter.getEndIndex();
    if (iter.getIndex() == end)
      return DONE;

    while (iter.getIndex() < end)
      {
	char c = iter.current();
	int type = Character.getType(c);

	char n = iter.next();

	if (n == CharacterIterator.DONE
	    || type == Character.PARAGRAPH_SEPARATOR
	    || type == Character.LINE_SEPARATOR)
	  break;

	// Handle two cases where we must scan for non-spacing marks.
	int start = iter.getIndex();
	if (type == Character.SPACE_SEPARATOR
	    || type == Character.START_PUNCTUATION
	    || isIdeo (c))
	  {
	    while (n != CharacterIterator.DONE
		   && Character.getType(n) == Character.NON_SPACING_MARK)
	      n = iter.next();
	    if (n == CharacterIterator.DONE)
	      break;

	    if (type == Character.SPACE_SEPARATOR)
	      {
		int nt = Character.getType(n);
		if (nt != Character.NON_SPACING_MARK
		    && nt != Character.SPACE_SEPARATOR
		    && ! isNb (n))
		  break;
	      }
	    else if (type == Character.START_PUNCTUATION)
	      {
		if (isIdeo (n))
		  {
		    // Open punctuation followed by non spacing marks
		    // and then ideograph does not have a break in
		    // it.  So skip all this.
		    start = iter.getIndex();
		  }
	      }
	    else
	      {
		// Ideograph preceded this character.
		if (isClose (Character.getType(n)))
		  break;
	      }
	  }
	iter.setIndex(start);
      }

    return iter.getIndex();
  }

  public int previous ()
  {
    int start = iter.getBeginIndex();
    if (iter.getIndex() == start)
      return DONE;

    while (iter.getIndex() >= start)
      {
	char c = iter.previous();
	if (c == CharacterIterator.DONE)
	  break;
	int type = Character.getType(c);

	char n = iter.previous();
	if (n == CharacterIterator.DONE)
	  break;
	iter.next();

	int nt = Character.getType(n);
	// Break after paragraph separators.
	if (nt == Character.PARAGRAPH_SEPARATOR
	    || nt == Character.LINE_SEPARATOR)
	  break;

	// Skip non-spacing marks.
	int init = iter.getIndex();
	while (n != CharacterIterator.DONE && nt == Character.NON_SPACING_MARK)
	  {
	    n = iter.previous();
	    nt = Character.getType(n);
	  }

	if (nt == Character.SPACE_SEPARATOR
	    && type != Character.SPACE_SEPARATOR
	    && type != Character.NON_SPACING_MARK
	    && ! isNb (c))
	  break;
	if (! isClose (type) && isIdeo (n))
	  break;
	if (isIdeo (c) && nt != Character.START_PUNCTUATION)
	  break;
	iter.setIndex(init);
      }

    return iter.getIndex();
  }
}