defaultenv: simplify usage

* src/ltlenv/defaultenv.hh, src/ltlenv/defaultenv.cc (require): Return
an atomic_prop*, not a formula*.
* src/bin/randaut.cc, src/bin/randltl.cc, src/ltlvisit/apcollect.cc,
src/tgbatest/ltl2tgba.cc, src/tgbatest/randtgba.cc: Do not cast
the return of require().

src/bin/randaut.cc

@@ -31,7 +31,6 @@
 #include "common_range.hh"
 #include "common_cout.hh"
 
-#include "ltlast/atomic_prop.hh"
 #include "ltlenv/defaultenv.hh"
 #include "misc/random.hh"
 
@@ -242,8 +241,7 @@ parse_opt(int key, char* arg, struct argp_state* as)
 	      break;
 	    }
 	}
-      aprops.insert(static_cast<const spot::ltl::atomic_prop*>
+      aprops.insert(spot::ltl::default_environment::instance().require(arg));
-		    (spot::ltl::default_environment::instance().require(arg)));
       break;
 
     default:

src/bin/randltl.cc

@@ -32,7 +32,6 @@
 #include "common_r.hh"
 
 #include <sstream>
-#include "ltlast/atomic_prop.hh"
 #include "ltlast/multop.hh"
 #include "ltlast/unop.hh"
 #include "ltlvisit/randomltl.hh"
@@ -156,7 +155,7 @@ remove_some_props(spot::ltl::atomic_prop_set& s)
 
   while (n--)
     {
-      spot::ltl::atomic_prop_set::iterator i = s.begin();
+      auto i = s.begin();
       std::advance(i, spot::mrand(s.size()));
       s.erase(i);
     }
@@ -260,8 +259,7 @@ parse_opt(int key, char* arg, struct argp_state* as)
 	      break;
 	    }
 	}
-      aprops.insert(static_cast<const spot::ltl::atomic_prop*>
+      aprops.insert(spot::ltl::default_environment::instance().require(arg));
-		    (spot::ltl::default_environment::instance().require(arg)));
       break;
     default:
       return ARGP_ERR_UNKNOWN;

src/ltlenv/defaultenv.cc

@@ -20,7 +20,6 @@
 // You should have received a copy of the GNU General Public License
 // along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
-#include "ltlast/atomic_prop.hh"
 #include "defaultenv.hh"
 
 namespace spot
@@ -32,7 +31,7 @@ namespace spot
     {
     }
 
-    const formula*
+    const atomic_prop*
     default_environment::require(const std::string& s)
     {
       return atomic_prop::instance(s, *this);

src/ltlenv/defaultenv.hh

@@ -24,6 +24,7 @@
 # define SPOT_LTLENV_DEFAULTENV_HH
 
 # include "environment.hh"
+# include "ltlast/atomic_prop.hh"
 
 namespace spot
 {
@@ -41,7 +42,7 @@ namespace spot
     {
     public:
       virtual ~default_environment();
-      virtual const formula* require(const std::string& prop_str);
+      virtual const atomic_prop* require(const std::string& prop_str);
       virtual const std::string& name() const;
 
       /// Get the sole instance of spot::ltl::default_environment.

src/ltlvisit/apcollect.cc

@@ -61,8 +61,7 @@ namespace spot
 	{
 	  std::ostringstream p;
 	  p << 'p' << i;
-	  res.insert(static_cast<const spot::ltl::atomic_prop*>
+	  res.insert(e.require(p.str()));
-		     (e.require(p.str())));
 	}
       return res;
     }

src/tgbatest/ltl2tgba.cc

@@ -386,7 +386,7 @@ checked_main(int argc, char** argv)
   bool opt_stutterize = false;
   bool spin_comments = false;
   const char* hoa_opt = 0;
-  spot::ltl::environment& env(spot::ltl::default_environment::instance());
+  auto& env = spot::ltl::default_environment::instance();
   spot::ltl::atomic_prop_set* unobservables = 0;
   spot::tgba_ptr system_aut = 0;
   auto dict = spot::make_bdd_dict();
@@ -846,8 +846,7 @@ checked_main(int argc, char** argv)
 	  const char* tok = strtok(argv[formula_index] + 2, ", \t;");
 	  while (tok)
 	    {
-	      unobservables->insert
+	      unobservables->insert(env.require(tok));
-		(static_cast<const spot::ltl::atomic_prop*>(env.require(tok)));
 	      tok = strtok(0, ", \t;");
 	    }
 	}

src/tgbatest/randtgba.cc

@@ -40,7 +40,6 @@
 #include "tgbaalgos/save.hh"
 #include "tgbaalgos/stats.hh"
 #include "ltlenv/defaultenv.hh"
-#include "ltlast/atomic_prop.hh"
 #include "tgbaalgos/dotty.hh"
 #include "tgbaparse/public.hh"
 #include "misc/random.hh"
@@ -586,7 +585,7 @@ main(int argc, char** argv)
 
   spot::option_map options;
 
-  spot::ltl::environment& env(spot::ltl::default_environment::instance());
+  auto& env = spot::ltl::default_environment::instance();
   spot::ltl::atomic_prop_set* ap = new spot::ltl::atomic_prop_set;
   auto dict = spot::make_bdd_dict();
 
@@ -794,8 +793,7 @@ main(int argc, char** argv)
 	}
       else
 	{
-	  ap->insert(static_cast<const spot::ltl::atomic_prop*>
+	  ap->insert(env.require(argv[argn]));
-		     (env.require(argv[argn])));
 	}
     }
 
@@ -886,7 +884,7 @@ main(int argc, char** argv)
 		spot::ltl::atomic_prop_collect(f);
               for (spot::ltl::atomic_prop_set::iterator i = tmp->begin();
 		   i != tmp->end(); ++i)
-		apf->insert(dynamic_cast<const spot::ltl::atomic_prop*>
+		apf->insert(down_cast<const spot::ltl::atomic_prop*>
 			    ((*i)->clone()));
               f->destroy();
               delete tmp;