// This file is part of PUMA.
// Copyright (C) 1999-2003  The PUMA developer team.
//                                                                
// This program 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 of 
// the License, or (at your option) any later version.            
//                                                                
// This program 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 this program; if not, write to the Free     
// Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, 
// MA  02111-1307  USA                                            

#ifndef __SyntaxState_ah__
#define __SyntaxState_ah__

#include "Puma/Syntax.h"
#include "Puma/Semantic.h"

// This aspect automatically save the parser state before a new rule is
// check. If the rule fails, the state is restored.

aspect SyntaxState {

  advice Puma::Syntax::rule_call() : around () {
    Puma::Syntax &s = *tjp->arg<0>();
    Puma::Syntax::State state = s.save_state ();
    tjp->proceed ();
    if (*tjp->result()) {
      s.forget_state ();
    } else {
      s.set_state (state);
      s.restore_state ();
    }
  }

};

#endif /* __SyntaxState_ah__ */