libjava/gnu/gcj/text/WordBreakIterator.java

// Default word BreakIterator.

/* Copyright (C) 1999  Free Software Foundation

   This file is part of libgcj.

This software is copyrighted work licensed under the terms of the
Libgcj License.  Please consult the file "LIBGCJ_LICENSE" for
details.  */

package gnu.gcj.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 WordBreakIterator extends BaseBreakIterator
{
  public Object clone ()
  {
    return new WordBreakIterator (this);
  }

  public WordBreakIterator ()
  {
    iter = null;
  }

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

  // Some methods to tell us different properties of characters.
  private final boolean isHira (char c)
  {
    return c >= 0x3040 && c <= 0x309f;
  }
  private final boolean isKata (char c)
  {
    return c >= 0x30a0 && c <= 0x30ff;
  }
  private final boolean isHan (char c)
  {
    return c >= 0x4e00 && c <= 0x9fff;
  }

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

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

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

	// Break after paragraph separators.
	if (type == Character.PARAGRAPH_SEPARATOR
	    || type == Character.LINE_SEPARATOR)
	  break;

	// Break between letters and non-letters.
	// FIXME: we treat apostrophe as part of a word.  This
	// is an English-ism.
	boolean is_letter = Character.isLetter(c);
	if (c != '\'' && ! is_letter && type != Character.NON_SPACING_MARK
	    && Character.isLetter(n))
	  break;

	// Always break after certain symbols, such as punctuation.
	// This heuristic is derived from hints in the JCL book and is
	// not part of Unicode.  It seems to be right, however.
	// FIXME: we treat apostrophe as part of a word.  This
	// is an English-ism.
	if (c != '\''
	    && (type == Character.DASH_PUNCTUATION
		|| type == Character.START_PUNCTUATION
		|| type == Character.END_PUNCTUATION
		|| type == Character.CONNECTOR_PUNCTUATION
		|| type == Character.OTHER_PUNCTUATION
		|| type == Character.MATH_SYMBOL
		|| type == Character.CURRENCY_SYMBOL
		|| type == Character.MODIFIER_SYMBOL
		|| type == Character.OTHER_SYMBOL
		|| type == Character.FORMAT
		|| type == Character.CONTROL))
	  break;

	boolean is_hira = isHira (c);
	boolean is_kata = isKata (c);
	boolean is_han = isHan (c);

	// Special case Japanese.
	if (! is_hira && ! is_kata && ! is_han
	    && type != Character.NON_SPACING_MARK
	    && (isHira (n) || isKata (n) || isHan (n)))
	  break;

	if (is_hira || is_kata || is_han || is_letter)
	  {
	    // Now we need to do some lookahead.  We might need to do
	    // quite a bit of lookahead, so we save our position and
	    // restore it later.
	    int save = iter.getIndex();
	    // Skip string of non spacing marks.
	    while (n != CharacterIterator.DONE
		   && Character.getType(n) == Character.NON_SPACING_MARK)
	      n = iter.next();
	    if (n == CharacterIterator.DONE)
	      break;
	    if ((is_hira && ! isHira (n))
		|| (is_kata && ! isHira (n) && ! isKata (n))
		|| (is_han && ! isHira (n) && ! isHan (n))
		// FIXME: we treat apostrophe as part of a word.  This
		// is an English-ism.
		|| (is_letter && ! Character.isLetter(n) && n != '\''))
	      break;
	    iter.setIndex(save);
	  }
      }

    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;

	boolean is_hira = isHira (c);
	boolean is_kata = isKata (c);
	boolean is_han = isHan (c);
	boolean is_letter = Character.isLetter(c);

	char n = iter.previous();
	if (n == CharacterIterator.DONE)
	  break;
	iter.next();
	int type = Character.getType(n);
	// Break after paragraph separators.
	if (type == Character.PARAGRAPH_SEPARATOR
	    || type == Character.LINE_SEPARATOR)
	  break;

	// Break between letters and non-letters.
	// FIXME: we treat apostrophe as part of a word.  This
	// is an English-ism.
	if (n != '\'' && ! Character.isLetter(n)
	    && type != Character.NON_SPACING_MARK
	    && is_letter)
	  break;

	// Always break after certain symbols, such as punctuation.
	// This heuristic is derived from hints in the JCL book and is
	// not part of Unicode.  It seems to be right, however.
	// FIXME: we treat apostrophe as part of a word.  This
	// is an English-ism.
	if (n != '\''
	    && (type == Character.DASH_PUNCTUATION
		|| type == Character.START_PUNCTUATION
		|| type == Character.END_PUNCTUATION
		|| type == Character.CONNECTOR_PUNCTUATION
		|| type == Character.OTHER_PUNCTUATION
		|| type == Character.MATH_SYMBOL
		|| type == Character.CURRENCY_SYMBOL
		|| type == Character.MODIFIER_SYMBOL
		|| type == Character.OTHER_SYMBOL
		|| type == Character.FORMAT
		|| type == Character.CONTROL))
	  break;

	// Special case Japanese.
	if ((is_hira || is_kata || is_han)
	    && ! isHira (n) && ! isKata (n) && ! isHan (n)
	    && type != Character.NON_SPACING_MARK)
	  break;

	// We might have to skip over non spacing marks to see what's
	// on the other side.
	if (! is_hira || (! is_letter && c != '\''))
	  {
	    int save = iter.getIndex();
	    while (n != CharacterIterator.DONE
		   && Character.getType(n) == Character.NON_SPACING_MARK)
	      n = iter.previous();
	    iter.setIndex(save);
	    // This is a strange case: a bunch of non-spacing marks at
	    // the beginning.  We treat the current location as a word
	    // break.
	    if (n == CharacterIterator.DONE)
	      break;
	    if ((isHira (n) && ! is_hira)
		|| (isKata (n) && ! is_hira && ! is_kata)
		|| (isHan (n) && ! is_hira && ! is_han)
		// FIXME: we treat apostrophe as part of a word.  This
		// is an English-ism.
		|| (! is_letter && c != '\'' && Character.isLetter(n)))
	      break;
	  }
      }

    return iter.getIndex();
  }
}