revamp the formula hierarchy (montro-patch)

Flatten the formula ltl::formula hiearchy into a single ltl::vnode that
has an enumerator to distinguish the types of node, and a common
interface to access children, update reference counts, etc.  The
ltl::formula class is now a thin wrapper around an ltl::vnode pointer to
keep track of reference counts automatically.  Visitor are not used
anymore; we now have map() and traversor() methods that are more
concise.

This basically fixes #43, but should be followed by some fine tuning
that should now be localized to the formula.hh and formula.cc files.

Some statistics about this patch.  I started working on it on Sep 9, had
a first compiling version two weeks later on Sep 22, and it then took 5
days to fixes the ~70 distincts bugs that were introduced during the
conversion.  About 13200 lines were modified, and one third of those
were removed.

* src/ltlast/formula.cc, src/ltlast/formula.hh: Complete rewrite,
including what was in separate nearby files.
* src/ltlast/allnodes.hh, src/ltlast/atomic_prop.cc,
src/ltlast/atomic_prop.hh, src/ltlast/binop.cc, src/ltlast/binop.hh,
src/ltlast/bunop.cc, src/ltlast/bunop.hh, src/ltlast/constant.cc,
src/ltlast/constant.hh, src/ltlast/multop.cc, src/ltlast/multop.hh,
src/ltlast/unop.cc, src/ltlast/unop.hh, src/ltlvisit/dump.cc,
src/ltlvisit/dump.hh, src/ltlast/predecl.hh: Delete these files.  Their
feature have been merged in formula.hh and formula.cc.
* src/ltlast/visitor.hh, src/ltlvisit/clone.cc, src/ltlvisit/clone.hh,
src/ltlvisit/dump.hh, src/ltlvisit/postfix.cc, src/ltlvisit/postfix.hh:
Delete these files, as we do not use visitors anymore.
* bench/stutter/stutter_invariance_formulas.cc,
bench/stutter/stutter_invariance_randomgraph.cc, doc/org/tut01.org,
doc/org/tut02.org, doc/org/tut10.org, doc/org/tut22.org,
iface/ltsmin/ltsmin.cc, iface/ltsmin/ltsmin.hh,
iface/ltsmin/modelcheck.cc, src/bin/autfilt.cc,
src/bin/common_aoutput.cc, src/bin/common_aoutput.hh,
src/bin/common_finput.cc, src/bin/common_finput.hh,
src/bin/common_output.cc, src/bin/common_output.hh,
src/bin/common_trans.cc, src/bin/common_trans.hh, src/bin/dstar2tgba.cc,
src/bin/genltl.cc, src/bin/ltl2tgba.cc, src/bin/ltl2tgta.cc,
src/bin/ltlcross.cc, src/bin/ltldo.cc, src/bin/ltlfilt.cc,
src/bin/ltlgrind.cc, src/bin/randaut.cc, src/bin/randltl.cc,
src/kripke/kripkeexplicit.cc, src/kripke/kripkeexplicit.hh,
src/kripkeparse/kripkeparse.yy, src/ltlast/Makefile.am,
src/ltlenv/declenv.cc, src/ltlenv/declenv.hh, src/ltlenv/defaultenv.cc,
src/ltlenv/defaultenv.hh, src/ltlenv/environment.hh,
src/ltlparse/ltlparse.yy, src/ltlparse/public.hh,
src/ltlvisit/Makefile.am, src/ltlvisit/apcollect.cc,
src/ltlvisit/apcollect.hh, src/ltlvisit/contain.cc,
src/ltlvisit/contain.hh, src/ltlvisit/dot.cc, src/ltlvisit/dot.hh,
src/ltlvisit/exclusive.cc, src/ltlvisit/exclusive.hh,
src/ltlvisit/length.cc, src/ltlvisit/length.hh, src/ltlvisit/mark.cc,
src/ltlvisit/mark.hh, src/ltlvisit/mutation.cc,
src/ltlvisit/mutation.hh, src/ltlvisit/nenoform.cc,
src/ltlvisit/nenoform.hh, src/ltlvisit/print.cc, src/ltlvisit/print.hh,
src/ltlvisit/randomltl.cc, src/ltlvisit/randomltl.hh,
src/ltlvisit/relabel.cc, src/ltlvisit/relabel.hh,
src/ltlvisit/remove_x.cc, src/ltlvisit/remove_x.hh,
src/ltlvisit/simpfg.cc, src/ltlvisit/simpfg.hh,
src/ltlvisit/simplify.cc, src/ltlvisit/simplify.hh, src/ltlvisit/snf.cc,
src/ltlvisit/snf.hh, src/ltlvisit/unabbrev.cc, src/ltlvisit/unabbrev.hh,
src/parseaut/parseaut.yy, src/ta/taexplicit.cc, src/ta/tgtaexplicit.cc,
src/taalgos/minimize.cc, src/taalgos/tgba2ta.cc, src/tests/bare.test,
src/tests/checkpsl.cc, src/tests/checkta.cc,
src/tests/complementation.cc, src/tests/consterm.cc,
src/tests/emptchk.cc, src/tests/equalsf.cc, src/tests/ikwiad.cc,
src/tests/isop.test, src/tests/kind.cc, src/tests/length.cc,
src/tests/ltldo.test, src/tests/ltlfilt.test, src/tests/ltlgrind.test,
src/tests/ltlprod.cc, src/tests/ltlrel.cc,
src/tests/parse_print_test.cc, src/tests/parseaut.test,
src/tests/parseerr.test, src/tests/randtgba.cc, src/tests/readltl.cc,
src/tests/reduc.cc, src/tests/syntimpl.cc, src/tests/taatgba.cc,
src/tests/tostring.cc, src/tests/twagraph.cc, src/tests/utf8.test,
src/twa/acc.cc, src/twa/bdddict.cc, src/twa/bdddict.hh,
src/twa/bddprint.cc, src/twa/formula2bdd.cc, src/twa/formula2bdd.hh,
src/twa/taatgba.cc, src/twa/taatgba.hh, src/twa/twa.cc, src/twa/twa.hh
src/twa/twagraph.cc, src/twa/twagraph.hh, src/twa/twasafracomplement.cc,
src/twaalgos/compsusp.cc, src/twaalgos/compsusp.hh,
src/twaalgos/dtgbasat.cc, src/twaalgos/hoa.cc, src/twaalgos/lbtt.cc,
src/twaalgos/ltl2taa.cc, src/twaalgos/ltl2taa.hh,
src/twaalgos/ltl2tgba_fm.cc, src/twaalgos/ltl2tgba_fm.hh,
src/twaalgos/minimize.cc, src/twaalgos/minimize.hh,
src/twaalgos/neverclaim.cc, src/twaalgos/postproc.cc,
src/twaalgos/postproc.hh, src/twaalgos/powerset.cc,
src/twaalgos/powerset.hh, src/twaalgos/randomgraph.cc,
src/twaalgos/remprop.cc, src/twaalgos/remprop.hh, src/twaalgos/stats.cc,
src/twaalgos/stats.hh, src/twaalgos/stutter.cc, src/twaalgos/stutter.hh,
src/twaalgos/translate.cc, src/twaalgos/translate.hh,
wrap/python/ajax/spotcgi.in, wrap/python/spot.py,
wrap/python/spot_impl.i, wrap/python/Makefile.am,
wrap/python/tests/automata-io.ipynb, wrap/python/tests/formulas.ipynb,
wrap/python/tests/ltl2tgba.py, wrap/python/tests/ltlparse.py,
wrap/python/tests/ltlsimple.py, wrap/python/tests/randltl.ipynb: Adjust
to use the new interface.
* src/sanity/style.test: Accept more C++11 patterns.
* NEWS: Mention the change.

src/ltlvisit/contain.cc

@@ -22,10 +22,7 @@
 
 #include "contain.hh"
 #include "simplify.hh"
-#include "ltlast/unop.hh"
-#include "ltlast/binop.hh"
-#include "ltlast/multop.hh"
-#include "ltlast/constant.hh"
+#include "ltlast/formula.hh"
 #include "twaalgos/product.hh"
 
 namespace spot
@@ -50,13 +47,7 @@ namespace spot
     void
     language_containment_checker::clear()
     {
-      while (!translated_.empty())
-	{
-	  trans_map::iterator i = translated_.begin();
-	  const formula* f = i->first;
-	  translated_.erase(i);
-	  f->destroy();
-	}
+      translated_.clear();
     }
 
     bool
@@ -75,31 +66,26 @@ namespace spot
 
     // Check whether L(l) is a subset of L(g).
     bool
-    language_containment_checker::contained(const formula* l,
-					    const formula* g)
+    language_containment_checker::contained(formula l,
+					    formula g)
     {
       if (l == g)
 	return true;
       record_* rl = register_formula_(l);
-      const formula* ng = unop::instance(unop::Not, g->clone());
-      record_* rng = register_formula_(ng);
-      ng->destroy();
+      record_* rng = register_formula_(formula::Not(g));
       return incompatible_(rl, rng);
     }
 
     // Check whether L(!l) is a subset of L(g).
     bool
-    language_containment_checker::neg_contained(const formula* l,
-						const formula* g)
+    language_containment_checker::neg_contained(formula l,
+						formula g)
     {
       if (l == g)
 	return false;
-      const formula* nl = unop::instance(unop::Not, l->clone());
+      formula nl = formula::Not(l);
       record_* rnl = register_formula_(nl);
-      const formula* ng = unop::instance(unop::Not, g->clone());
-      record_* rng = register_formula_(ng);
-      nl->destroy();
-      ng->destroy();
+      record_* rng = register_formula_(formula::Not(g));
       if (nl == g)
 	return true;
       return incompatible_(rnl, rng);
@@ -107,8 +93,8 @@ namespace spot
 
     // Check whether L(l) is a subset of L(!g).
     bool
-    language_containment_checker::contained_neg(const formula* l,
-						const formula* g)
+    language_containment_checker::contained_neg(formula l,
+						formula g)
     {
       if (l == g)
 	return false;
@@ -119,13 +105,13 @@ namespace spot
 
     // Check whether L(l) = L(g).
     bool
-    language_containment_checker::equal(const formula* l, const formula* g)
+    language_containment_checker::equal(formula l, formula g)
     {
       return contained(l, g) && contained(g, l);
     }
 
     language_containment_checker::record_*
-    language_containment_checker::register_formula_(const formula* f)
+    language_containment_checker::register_formula_(formula f)
     {
       trans_map::iterator i = translated_.find(f);
       if (i != translated_.end())
@@ -133,17 +119,17 @@ namespace spot
 
       auto e = ltl_to_tgba_fm(f, dict_, exprop_, symb_merge_,
 			      branching_postponement_, fair_loop_approx_);
-      record_& r = translated_[f->clone()];
+      record_& r = translated_[f];
       r.translation = e;
       return &r;
     }
 
 
-    const formula*
-    reduce_tau03(const formula* f, bool stronger)
+    formula
+    reduce_tau03(formula f, bool stronger)
     {
-      if (!f->is_psl_formula())
-	return f->clone();
+      if (!f.is_psl_formula())
+	return f;
 
       ltl_simplifier_options opt(false, false, false,
 				 true, stronger);