Make direct children of a class publicly available

Previously it was only possible to retrieve all children of a class
(i.e. those that inherit directly and those that inherit by
transitivity) given its ID. The new function retrieves only those
children that inherit directly from the given class.

Author: antlechner

src/goto-programs/class_hierarchy.cpp

@@ -88,24 +88,39 @@ void class_hierarchy_grapht::populate(const symbol_tablet &symbol_table)
   }
 }
 
+/// Get all the classes that directly (i.e. in one step) inherit from class c.
+/// \param c: The class to consider
+/// \return A list containing ids of all direct children of c.
+class_hierarchyt::idst
+class_hierarchyt::get_direct_children(const irep_idt &c) const
+{
+  idst dest;
+  class_mapt::const_iterator it = class_map.find(c);
+  if(it == class_map.end())
+    return dest;
+  const entryt &entry = it->second;
+  for(const auto &child : entry.children)
+    dest.push_back(child);
+  return dest;
+}
+
+/// Get all the classes that inherit (directly or indirectly) from class c.
+/// \param c: The class to consider
+/// \param [out] dest: A list containing ids of all classes that eventually
+///   inherit from c.
 void class_hierarchyt::get_children_trans_rec(
   const irep_idt &c,
   idst &dest) const
 {
-  class_mapt::const_iterator it=class_map.find(c);
-  if(it==class_map.end())
-    return;
-  const entryt &entry=it->second;
-
-  for(const auto &child : entry.children)
+  const idst &next_children = get_direct_children(c);
+  for(const auto child : next_children)
     dest.push_back(child);
-
   // recursive calls
-  for(const auto &child : entry.children)
+  for(const auto &child : next_children)
     get_children_trans_rec(child, dest);
 }
 
-/// Get all the classes that inherit (directly or indirectly) from class c. The
+/// Get all the classes that class c inherits from (directly or indirectly). The
 /// first element(s) will be the immediate parents of c, though after this
 /// the order is all the parents of the first immediate parent
 /// \param c: The class to consider

src/goto-programs/class_hierarchy.h

@@ -51,6 +51,8 @@ class class_hierarchyt
 
   void operator()(const symbol_tablet &);
 
+  idst get_direct_children(const irep_idt &c) const;
+
   // transitively gets all children
   idst get_children_trans(const irep_idt &id) const
   {