Define function template for output_dot

This makes output_dot more reusable as we don't have to inherit from
grapht to use it.

Author: romainbrenguier

src/util/graph.h

@@ -20,6 +20,7 @@ Author: Daniel Kroening, [email protected]
 #include <cassert>
 #include <algorithm>
 #include <queue>
+#include <functional>
 
 #include "invariant.h"
 
@@ -264,8 +265,12 @@ class grapht
 
   std::list<node_indext> topsort() const;
 
+  std::vector<node_indext> get_successors(const node_indext &n) const;
   void output_dot(std::ostream &out) const;
   void output_dot_node(std::ostream &out, node_indext n) const;
+  void for_each_successor(
+    const node_indext &n,
+    std::function<void(const node_indext &)> f) const;
 
 protected:
   class tarjant
@@ -668,23 +673,54 @@ std::list<typename grapht<N>::node_indext> grapht<N>::topsort() const
   return nodelist;
 }
 
-template<class N>
-void grapht<N>::output_dot(std::ostream &out) const
+template <typename node_index_type>
+void output_dot_generic(
+  std::ostream &out,
+  node_index_type size,
+  const std::function<
+    void(const node_index_type &, std::function<void(const node_index_type &)>)>
+    &for_each_succ)
 {
-  for(node_indext n=0; n<nodes.size(); n++)
-    output_dot_node(out, n);
+  for(node_index_type i = 0; i < size; ++i)
+    for_each_succ(
+      i, [&](const node_index_type &n) { out << i << " -> " << n << '\n'; });
 }
 
-template<class N>
-void grapht<N>::output_dot_node(std::ostream &out, node_indext n) const
+template <class N>
+std::vector<typename grapht<N>::node_indext>
+grapht<N>::get_successors(const node_indext &n) const
 {
-  const nodet &node=nodes[n];
+  std::vector<node_indext> result;
+  std::transform(
+    nodes[n].out.begin(),
+    nodes[n].out.end(),
+    std::back_inserter(result),
+    [&](const std::pair<node_indext, edget> &edge) { return edge.first; });
+  return result;
+}
 
-  for(typename edgest::const_iterator
-      it=node.out.begin();
-      it!=node.out.end();
-      it++)
-    out << n << " -> " << it->first << '\n';
+template <class N>
+void grapht<N>::for_each_successor(
+  const node_indext &n,
+  std::function<void(const node_indext &)> f) const
+{
+  std::for_each(
+    nodes[n].out.begin(),
+    nodes[n].out.end(),
+    [&](const std::pair<node_indext, edget> &edge) { f(edge.first); });
+}
+
+template <class N>
+void grapht<N>::output_dot(std::ostream &out) const
+{
+  output_dot_generic<node_indext>(
+    out,
+    (node_indext)nodes.size(),
+    [&](
+      const node_indext &i,
+      const std::function<void(const node_indext &)> &f) { // NOLINT
+      for_each_successor(i, f);
+    });
 }
 
 #endif // CPROVER_UTIL_GRAPH_H