Implements spot::ltl::destroy() and exercise it.

* src/ltlast/atomic_prop.hh: Declare instance_count().
* src/ltlast/binop.hh, src/ltlast/unop.hh, src/ltlast/multop.hh:
Likewise.  Also, really inherit for ref_formula this time.
* src/ltlast/atomic_prop.cc, src/ltlast/binop.cc,
src/ltlast/unop.cc, src/ltlast/multop.cc: On destruction, suppress
the instance from the instance map.  Implement instance_count().
* src/ltlast/formula.cc, src/ltlast/formula.hh,
src/ltlast/ref_formula.cc, src/ltlast/ref_formula.hh: Add virtual
destructors.
* src/ltlparse/ltlparse.yy: Recover from binary operators with
missing right hand operand (the point is just to destroy the
the left hand operand).
* src/ltltest/equals.cc, src/ltltest/readltl.cc,
src/ltltest/tostring.cc: Destroy used formulae.  Make sure
instance_count()s are null are the end.
* src/ltltest/parseerr.test: Adjust expected result, now
that the parser lnows about missing right hand operands.
* src/ltlvisit/destroy.hh, src/ltlvisit/destroy.cc,
src/ltlvisit/postfix.hh, src/ltlvisit/postfix.cc: New files.
* src/ltlvisit/Makefile.am (libltlvisit_la_SOURCES): Add them.
* src/ltlvisit/lunabbrev.cc (Xor, Equiv): Clone formulae
occurring twice in the rewritten expression.

src/ltlast/atomic_prop.cc

@@ -13,6 +13,11 @@ namespace spot
 
     atomic_prop::~atomic_prop()
     {
+      // Get this instance out of the instance map.
+      pair p(name(), &env());
+      map::iterator i = instances.find(p);
+      assert (i != instances.end());
+      instances.erase(i);
     }
 
     void
@@ -55,5 +60,11 @@ namespace spot
       return static_cast<atomic_prop*>(ap->ref());
     }
 
+    unsigned
+    atomic_prop::instance_count()
+    {
+      return instances.size();
+    }
+
   }
 }

src/ltlast/atomic_prop.hh

@@ -26,6 +26,10 @@ namespace spot
       const std::string& name() const;
       /// Get the environment of the atomic proposition.
       environment& env() const;
+
+      /// Number of instantiated atomic propositions.  For debugging.
+      static unsigned instance_count();
+
     protected:
       atomic_prop(const std::string& name, environment& env);
       virtual ~atomic_prop();

src/ltlast/binop.cc

@@ -13,6 +13,12 @@ namespace spot
 
     binop::~binop()
     {
+      // Get this instance out of the instance map.
+      pairf pf(first(), second());
+      pair p(op(), pf);
+      map::iterator i = instances.find(p);
+      assert (i != instances.end());
+      instances.erase(i);
     }
 
     void
@@ -95,5 +101,10 @@ namespace spot
       return static_cast<binop*>(ap->ref());
     }
 
+    unsigned
+    binop::instance_count()
+    {
+      return instances.size();
+    }
   }
 }

src/ltlast/binop.hh

@@ -2,7 +2,7 @@
 # define SPOT_LTLAST_BINOP_HH
 
 #include <map>
-#include "formula.hh"
+#include "refformula.hh"
 
 namespace spot
 {
@@ -10,7 +10,7 @@ namespace spot
   {
 
     /// Binary operator.
-    class binop : public formula
+    class binop : public ref_formula
     {
     public:
       /// Different kinds of binary opertaors
@@ -40,6 +40,9 @@ namespace spot
       /// Get the type of this operator, as a string.
       const char* op_name() const;
 
+      /// Number of instantiated binary operators.  For debugging.
+      static unsigned instance_count();
+
     protected:
       typedef std::pair<formula*, formula*> pairf;
       typedef std::pair<type, pairf> pair;

src/ltlast/formula.cc

@@ -11,6 +11,10 @@ namespace spot
       return this;
     }
 
+    formula::~formula()
+    {
+    }
+
     void
     formula::unref(formula* f)
     {

src/ltlast/formula.hh

@@ -15,6 +15,8 @@ namespace spot
     class formula
     {
     public:
+      virtual ~formula();
+
       virtual void accept(visitor& v) = 0;
       virtual void accept(const_visitor& v) const = 0;
 

src/ltlast/multop.cc

@@ -14,6 +14,12 @@ namespace spot
 
     multop::~multop()
     {
+      // Get this instance out of the instance map.
+      pair p(op(), children_);
+      map::iterator i = instances.find(p);
+      assert (i != instances.end());
+      instances.erase(i);
+
       delete children_;
     }
 
@@ -132,5 +138,10 @@ namespace spot
       *m = instance(op, v);
     }
 
+    unsigned
+    multop::instance_count()
+    {
+      return instances.size();
+    }
   }
 }

src/ltlast/multop.hh

@@ -3,7 +3,7 @@
 
 #include <vector>
 #include <map>
-#include "formula.hh"
+#include "refformula.hh"
 
 namespace spot
 {
@@ -13,7 +13,7 @@ namespace spot
     /// \brief Multi-operand operators.
     ///
     /// These operators are considered commutative and associative.
-    class multop : public formula
+    class multop : public ref_formula
     {
     public:
       enum type { Or, And };
@@ -61,6 +61,9 @@ namespace spot
       /// Get the type of this operator, as a string.
       const char* op_name() const;
 
+      /// Number of instantiated multi-operand operators.  For debugging.
+      static unsigned instance_count();
+
     protected:
       typedef std::vector<formula*> vec;
       typedef std::pair<type, vec*> pair;

src/ltlast/refformula.cc

@@ -10,6 +10,10 @@ namespace spot
     {
     }
 
+    ref_formula::~ref_formula()
+    {
+    }
+
     void
     ref_formula::ref_()
     {

src/ltlast/refformula.hh

@@ -12,6 +12,7 @@ namespace spot
     class ref_formula : public formula
     {
     protected:
+      virtual ~ref_formula();
       ref_formula();
       void ref_();
       bool unref_();

src/ltlast/unop.cc

@@ -13,6 +13,11 @@ namespace spot
 
     unop::~unop()
     {
+      // Get this instance out of the instance map.
+      pair p(op(), child());
+      map::iterator i = instances.find(p);
+      assert (i != instances.end());
+      instances.erase(i);
     }
 
     void
@@ -80,5 +85,10 @@ namespace spot
       return static_cast<unop*>(ap->ref());
     }
 
+    unsigned
+    unop::instance_count()
+    {
+      return instances.size();
+    }
   }
 }

src/ltlast/unop.hh

@@ -2,7 +2,7 @@
 # define SPOT_LTLAST_UNOP_HH
 
 #include <map>
-#include "formula.hh"
+#include "refformula.hh"
 
 namespace spot
 {
@@ -10,7 +10,7 @@ namespace spot
   {
 
     /// Unary operator.
-    class unop : public formula
+    class unop : public ref_formula
     {
     public:
       enum type { Not, X, F, G };
@@ -32,6 +32,9 @@ namespace spot
       /// Get the type of this operator, as a string.
       const char* op_name() const;
 
+      /// Number of instantiated unary operators.  For debugging.
+      static unsigned instance_count();
+
     protected:
       typedef std::pair<type, formula*> pair;
       typedef std::map<pair, formula*> map;