/*
 *  gnu/regexp/RETokenStart.java
 *  Copyright (C) 1998 Wes Biggs
 *
 *  This library is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU Library General Public License as published
 *  by the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  This library 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 Library General Public License for more details.
 *
 *  You should have received a copy of the GNU Library General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

package gnu.regexp;

class RETokenStart extends REToken {
  private boolean newline; // matches after a newline
  
  RETokenStart(int f_subIndex, boolean f_newline) {
    super(f_subIndex);
    newline = f_newline;
  }
  
  int[] match(CharIndexed input, int index, int eflags, REMatch mymatch) {
    // charAt(index-1) may be unknown on an InputStream. FIXME
    // Match after a newline if in multiline mode
    if (newline && (mymatch.offset > 0) && (input.charAt(index - 1) == '\n')) 
      return next(input,index,eflags,mymatch);

    // Don't match at all if REG_NOTBOL is set.
    if ((eflags & RE.REG_NOTBOL) > 0) return null;
    
    if ((eflags & RE.REG_ANCHORINDEX) > 0)
      return (mymatch.anchor == mymatch.offset) ? 
	next(input,index,eflags,mymatch) : null;
    else
      return ((index == 0) && (mymatch.offset == 0)) ?
	next(input,index,eflags,mymatch) : null;
  }

  void dump(StringBuffer os) {
    os.append('^');
  }
}