* src/ltlvisit/tostring.hh (to_spin_string): New function.

Convert a formula into a string parsable by Spin.
* src/tgbaalgos/neverclaim.hh, src/tgbaalgos/neverclaim.cc: New files.
Print the never claim in Spin format of a degeneralized TGBA.
* src/tgbaalgos/Makefile.am: Add them.
* src/tgbatest/ltl2tgba.cc: Add the option -N which outputs the
never claim in Spin format of a degeneralized TGBA.
* src/tgbatest/ltl2neverclaim.test: New file.
* src/tgbatest/Makefile.am: Add it.

src/tgbaalgos/neverclaim.hh

@@ -0,0 +1,35 @@
+// Copyright (C) 2004  Laboratoire d'Informatique de Paris 6 (LIP6),
+// département Systèmes Répartis Coopératifs (SRC), Université Pierre
+// et Marie Curie.
+//
+// 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 2 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 Spot; see the file COPYING.  If not, write to the Free
+// Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
+// 02111-1307, USA.
+
+#ifndef SPOT_TGBAALGOS_NEVERCLAIM_HH
+# define SPOT_TGBAALGOS_NEVERCLAIM_HH
+
+#include <iostream>
+#include "ltlast/formula.hh"
+#include "tgba/tgbatba.hh"
+
+namespace spot
+{
+  /// \brief Print reachable states in Spin never claim format.
+  std::ostream& never_claim_reachable(std::ostream& os, const tgba_tba_proxy* g, const ltl::formula* f=0);
+}
+
+#endif // SPOT_TGBAALGOS_NEVERCLAIM_HH