// -*- coding: utf-8 -*-
// Copyright (C) 2012, 2013, 2014 Laboratoire de Recherche et
// Developpement de l'Epita (LRDE).
//
// This file is part of Spot, a model checking library.
//
// Spot 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 3 of the License, or
// (at your option) any later version.
//
// Spot 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, see <http://www.gnu.org/licenses/>.

#ifndef SPOT_LTLVISIT_SNF_HH
#define SPOT_LTLVISIT_SNF_HH

#include "ltlast/formula.hh"
#include "misc/hash.hh"

namespace spot
{
  namespace ltl
  {

    typedef std::unordered_map<const formula*, const formula*,
			       ptr_hash<formula>> snf_cache;

    /// Helper to rewrite a sere in Star Normal Form.
    ///
    /// This should only be called on children of a Star operator.  It
    /// corresponds to the E° operation defined in the following
    /// paper.
    ///
    /** \verbatim
        @Article{	  bruggeman.96.tcs,
          author	= {Anne Br{\"u}ggemann-Klein},
          title		= {Regular Expressions into Finite Automata},
          journal	= {Theoretical Computer Science},
          year		= {1996},
          volume	= {120},
          pages		= {87--98}
        }
        \endverbatim */
    ///
    /// \param sere the SERE to rewrite
    /// \param cache an optional cache
    SPOT_API const formula*
    star_normal_form(const formula* sere, snf_cache* cache = 0);

    /// A variant of star_normal_form() for r[*0..j] where j < ω.
    SPOT_API const formula*
    star_normal_form_bounded(const formula* sere, snf_cache* cache = 0);
  }
}

#endif // SPOT_LTLVISIT_SNF_HH
