Introduce a translator class.

This perform pre- and post-processings in addition to
the LTL-to-TGBA translation.

* src/tgbaalgos/translate.cc, src/tgbaalgos/translate.hh: New files.
* src/tgbaalgos/Makefile.am: Add them.
* src/tgbaalgos/postproc.hh: Make the private part protected, so
that we can inherit from that in the translator class.
* src/bin/ltl2tgba.cc: Use the translator class to hide LTL
simplification, translation, and postprocessings.
* NEWS: Mention it.

src/tgbaalgos/translate.hh

@@ -0,0 +1,123 @@
+// -*- coding: utf-8 -*-
+// Copyright (C) 2013 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 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_TGBAALGOS_TRANSLATE_HH
+# define SPOT_TGBAALGOS_TRANSLATE_HH
+
+#include "postproc.hh"
+#include "ltlvisit/simplify.hh"
+
+namespace spot
+{
+  /// \brief Translate an LTL formula into an optimized spot::tgba.
+  /// \ingroup tgba_ltl
+  ///
+  /// This class implements a three-step translation:
+  /// - syntactic simplification of the formula
+  /// - translation of the formula into TGBA
+  /// - postprocessing of the resulting TGBA to minimize it, or
+  ///   turn it into the required form.
+  ///
+  /// Method set_type() may be used to specify the type of
+  /// automaton produced (TGBA, BA, Monitor).  The default is TGBA.
+  ///
+  /// Method set_pref() may be used to specify whether small automata
+  /// should be prefered over deterministic automata.
+  ///
+  /// Method set_level() may be used to specify the optimization level.
+  ///
+  /// The semantic of these three methods is inherited from the
+  /// spot::postprocessor class, but the optimization level is
+  /// additionally used to select which LTL simplifications to enable.
+  class translator: protected postprocessor
+  {
+  public:
+    translator(ltl::ltl_simplifier* simpl, const option_map* opt = 0)
+      : postprocessor(opt), simpl_(simpl), simpl_owned_(0)
+    {
+      assert(simpl);
+    }
+
+    translator(bdd_dict* dict, const option_map* opt = 0)
+      : postprocessor(opt)
+    {
+      build_simplifier(dict);
+    }
+
+    translator(const option_map* opt = 0)
+      : postprocessor(opt)
+    {
+      build_simplifier(0);
+    }
+
+    ~translator()
+    {
+      // simpl_owned_ is 0 if simpl_ was supplied to the constructor.
+      delete simpl_owned_;
+    }
+
+    void build_simplifier(bdd_dict* dict);
+
+    typedef postprocessor::output_type output_type;
+
+    void
+    set_type(output_type type)
+    {
+      this->postprocessor::set_type(type);
+    }
+
+    typedef postprocessor::output_pref output_pref;
+
+    void
+    set_pref(output_pref pref)
+    {
+      this->postprocessor::set_pref(pref);
+    }
+
+    typedef postprocessor::optimization_level optimization_level;
+
+    void
+    set_level(optimization_level level)
+    {
+      level_ = level;
+    }
+
+    /// \brief Convert \a f into an automaton.
+    ///
+    /// The formula \a f is simplified internally, but it is not
+    /// not destroyed (this is the responsibility of the caller).
+    const tgba* run(const ltl::formula* f);
+
+    /// \brief Convert \a f into an automaton, and update f.
+    ///
+    /// The formula <code>*f</code> is destroyed, and replaced
+    /// by the simplified version, which should be destroyed by
+    /// the caller.
+    const tgba* run(const ltl::formula** f);
+
+
+  private:
+    ltl::ltl_simplifier* simpl_;
+    ltl::ltl_simplifier* simpl_owned_;
+  };
+  /// @}
+}
+
+
+#endif // SPOT_TGBAALGOS_TRANSLATE_HH