Extracted out the converting constant boolean expressions

This allows other implementations of what constant boolean expressions
should be written as.

Author: thk123

src/ansi-c/expr2c.cpp

@@ -2216,11 +2216,7 @@ std::string expr2ct::convert_constant(
   }
   else if(type.id()==ID_bool)
   {
-    // C doesn't really have these
-    if(src.is_true())
-      dest="TRUE";
-    else
-      dest="FALSE";
+    dest = convert_constant_bool(src.is_true());
   }
   else if(type.id()==ID_unsignedbv ||
           type.id()==ID_signedbv ||
@@ -2236,11 +2232,7 @@ std::string expr2ct::convert_constant(
 
     if(type.id()==ID_c_bool)
     {
-      // C doesn't really have these
-      if(int_value!=0)
-        dest="TRUE";
-      else
-        dest="FALSE";
+      dest = convert_constant_bool(int_value != 0);
     }
     else if(type==char_type() && type!=signed_int_type() && type!=unsigned_int_type())
     {
@@ -2393,6 +2385,28 @@ std::string expr2ct::convert_constant(
 
 /*******************************************************************\
 
+Function: expr2ct::convert_constant_bool
+
+  Inputs:
+          boolean_value - The value of the constant bool expression
+
+ Outputs: Returns a C-like representation of the boolean value,
+          e.g. TRUE or FALSE.
+
+ Purpose: To get the C-like representation of a given boolean value.
+
+\*******************************************************************/
+std::string expr2ct::convert_constant_bool(bool boolean_value)
+{
+  // C doesn't really have these
+  if(boolean_value)
+    return "TRUE";
+  else
+    return "FALSE";
+}
+
+/*******************************************************************\
+
 Function: expr2ct::convert_struct
 
   Inputs:

src/ansi-c/expr2c_class.h

@@ -209,6 +209,7 @@ class expr2ct
   std::string convert_object_descriptor(const exprt &src, unsigned &precedence);
   std::string convert_literal(const exprt &src, unsigned &precedence);
   virtual std::string convert_constant(const constant_exprt &src, unsigned &precedence);
+  virtual std::string convert_constant_bool(bool boolean_value);
 
   std::string convert_norep(const exprt &src, unsigned &precedence);