/*
 *  gnu/regexp/RETokenStart.java
 *  Copyright (C) 1998-2001 Wes Biggs
 *
 *  This library is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU Lesser General Public License as published
 *  by the Free Software Foundation; either version 2.1 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 Lesser General Public License for more details.
 *
 *  You should have received a copy of the GNU Lesser 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 String newline; // matches after a newline
    
    RETokenStart(int f_subIndex, String f_newline) {
	super(f_subIndex);
	newline = f_newline;
    }
    
    boolean match(CharIndexed input, REMatch mymatch) {
	// charAt(index-n) may be unknown on a Reader/InputStream. FIXME
	// Match after a newline if in multiline mode
	
	if (newline != null) {
	    int len = newline.length();
	    if (mymatch.offset >= len) {
		boolean found = true;
		char z;
		int i = 0; // position in REToken.newline
		char ch = input.charAt(mymatch.index - len);
		do {
		    z = newline.charAt(i);
		    if (ch != z) {
			found = false;
			break;
		    }
		    ++i;
		    ch = input.charAt(mymatch.index - len + i);
		} while (i < len);
	    
		if (found) return next(input, mymatch);
	    }
	}
	
	// Don't match at all if REG_NOTBOL is set.
	if ((mymatch.eflags & RE.REG_NOTBOL) > 0) return false;
	
	if ((mymatch.eflags & RE.REG_ANCHORINDEX) > 0)
	    return (mymatch.anchor == mymatch.offset) ? 
		next(input, mymatch) : false;
	else
	    return ((mymatch.index == 0) && (mymatch.offset == 0)) ?
		next(input, mymatch) : false;
    }
    
    void dump(StringBuffer os) {
	os.append('^');
    }
}