relabel: implement relabeling of Boolean subexpressions.

* src/ltlast/multop.cc, src/ltlast/multop.hh (multop::boolean_operands,
multop::boolean_count): New methods.
* src/ltlvisit/relabel.cc, src/ltlvisit/relabel.hh
(relabel): Take an optional relabeling_map as parameter.
(relabel_bse): New.
* src/ltltest/ltlrel.test, src/ltltest/ltlrel.cc: New files.
* src/ltltest/Makefile.am: Add them.
* src/bin/ltlfilt.cc: Add option --relabel-bool.
* src/ltltest/ltlfilt.test: Test it.
* NEWS: Mention it.
* doc/org/ltlfilt.org: Illustrate it.

src/ltlast/multop.cc

@@ -1,5 +1,5 @@
-// Copyright (C) 2009, 2010, 2011, 2012 Laboratoire de Recherche et
-// Développement de l'Epita (LRDE).
+// Copyright (C) 2009, 2010, 2011, 2012, 2013 Laboratoire de Recherche
+// et Développement de l'Epita (LRDE).
 // Copyright (C) 2003, 2004, 2005 Laboratoire d'Informatique de
 // Paris 6 (LIP6), département Systèmes Répartis Coopératifs (SRC),
 // Université Pierre et Marie Curie.
@@ -147,6 +147,31 @@ namespace spot
       return instance(op_, v);
     }
 
+    unsigned
+    multop::boolean_count() const
+    {
+      unsigned pos = 0;
+      unsigned s = size();
+      while (pos < s && nth(pos)->is_boolean())
+	++pos;
+      return pos;
+    }
+
+    const formula*
+    multop::boolean_operands(unsigned* width) const
+    {
+      unsigned s = boolean_count();
+      if (width)
+	*width = s;
+      if (!s)
+	return 0;
+      vec* v = new vec(children_->begin(),
+		       children_->begin() + s);
+      for (unsigned n = 0; n < s; ++n)
+	(*v)[n]->clone();
+      return instance(op_, v);
+    }
+
     multop::type
     multop::op() const
     {
@@ -599,7 +624,7 @@ namespace spot
 	}
       else
 	{
-	  // The instance did not already exist. 
+	  // The instance did not already exist.
 	  res = ires.first->second = new multop(op, v);
 	}
       res->clone();

src/ltlast/multop.hh

@@ -138,6 +138,23 @@ namespace spot
       /// return a new formula <code>a|b|d</code>.
       const formula* all_but(unsigned n) const;
 
+      /// \brief return the number of Boolean operands in the binop.
+      ///
+      /// For instance if \c f <code>a|b|Xc|Gd</code>, this
+      /// returns 2.
+      unsigned boolean_count() const;
+
+      /// \brief return the Boolean part of the binop.
+      ///
+      /// For instance if \c f <code>a|b|Xc|Gd</code>, this
+      /// returns <code>a|b</code>.  Return 0 if there is no
+      /// Boolean operand.
+      ///
+      /// If \a width is not null, it is filled with the number
+      /// of Boolean operands extracted (i.e., the result
+      /// of boolean_count())
+      const formula* boolean_operands(unsigned* width = 0) const;
+
       /// Get the type of this operator.
       type op() const;
       /// Get the type of this operator, as a string.