Replace nondet_count by a functor

Author: romainbrenguier

src/goto-symex/goto_symex.cpp

@@ -13,7 +13,6 @@ Author: Daniel Kroening, [email protected]
 
 #include <util/simplify_expr.h>
 
-unsigned goto_symext::nondet_count=0;
 unsigned goto_symext::dynamic_counter=0;
 
 void goto_symext::do_simplify(exprt &expr)
@@ -22,7 +21,7 @@ void goto_symext::do_simplify(exprt &expr)
     simplify(expr, ns);
 }
 
-nondet_symbol_exprt build_symex_nondet(typet &type, unsigned &nondet_count)
+nondet_symbol_exprt symex_nondet_generatort::operator()(typet &type)
 {
   irep_idt identifier = "symex::nondet" + std::to_string(nondet_count++);
   nondet_symbol_exprt new_expr(identifier, type);

src/goto-symex/goto_symex.h

@@ -38,6 +38,16 @@ class namespacet;
 class side_effect_exprt;
 class typecast_exprt;
 
+/// Functor generating fresh nondet symbols
+class symex_nondet_generatort
+{
+public:
+  nondet_symbol_exprt operator()(typet &type);
+
+private:
+  unsigned nondet_count = 0;
+};
+
 /// \brief The main class for the forward symbolic simulator
 ///
 /// Higher-level architectural information on symbolic execution is
@@ -399,7 +409,7 @@ class goto_symext
   virtual void symex_input(statet &, const codet &);
   virtual void symex_output(statet &, const codet &);
 
-  static unsigned nondet_count;
+  symex_nondet_generatort build_symex_nondet;
   static unsigned dynamic_counter;
 
   void rewrite_quantifiers(exprt &, statet &);
@@ -449,8 +459,6 @@ class goto_symext
   }
 };
 
-nondet_symbol_exprt build_symex_nondet(typet &type, unsigned &nondet_count);
-
 void symex_transition(goto_symext::statet &state);
 
 void symex_transition(

src/goto-symex/symex_clean_expr.cpp

@@ -135,26 +135,26 @@ static void adjust_byte_extract_rec(exprt &expr, const namespacet &ns)
   }
 }
 
-static void replace_nondet(exprt &expr, unsigned &nondet_count)
+static void
+replace_nondet(exprt &expr, symex_nondet_generatort &build_symex_nondet)
 {
   if(expr.id() == ID_side_effect && expr.get(ID_statement) == ID_nondet)
   {
-    nondet_symbol_exprt new_expr =
-      build_symex_nondet(expr.type(), nondet_count);
+    nondet_symbol_exprt new_expr = build_symex_nondet(expr.type());
     new_expr.add_source_location() = expr.source_location();
     expr.swap(new_expr);
   }
   else
     Forall_operands(it, expr)
-      replace_nondet(*it, nondet_count);
+      replace_nondet(*it, build_symex_nondet);
 }
 
 void goto_symext::clean_expr(
   exprt &expr,
   statet &state,
   const bool write)
 {
-  replace_nondet(expr, nondet_count);
+  replace_nondet(expr, build_symex_nondet);
   dereference(expr, state, write);
 
   // make sure all remaining byte extract operations use the root