Visitors to transform <>-> into <>+> or to detect the latter.

* src/ltlvisit/mark.cc, src/ltlvisit/mark.hh: New files.
* src/ltlvisit/Makefile.am: Add mark.hh and mark.cc.

src/ltlvisit/mark.hh

@@ -0,0 +1,43 @@
+// Copyright (C) 2010 Laboratoire de Recherche et Développement 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 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_LTLVISIT_MARK_HH
+# define SPOT_LTLVISIT_MARK_HH
+
+#include "ltlast/formula.hh"
+#include "ltlast/visitor.hh"
+
+namespace spot
+{
+  namespace ltl
+  {
+    /// \brief Mark operators UConcat and EConcat.
+    /// \ingroup ltl_rewriting
+    ///
+    /// \param f The formula to rewrite.
+    formula* mark_concat_ops(const formula* f);
+
+    bool simplify_mark(formula*& f);
+
+    bool has_mark(const formula* f);
+  }
+}
+
+#endif //  SPOT_LTLVISIT_MARK_HH