Add proxy version of ElemCorner::build_edge

Author: loganharbour

include/geom/elem_corner.h

@@ -157,7 +157,11 @@ class ElemCorner : public std::pair<unsigned short, unsigned short>
   { set_edge(vs.first, vs.second); }
 
   /**
-   * @returns The edge when at an edge
+   * Builds an edge of element \p elem into the Elem \p edge when at an edge
+   */
+  void build_edge(const Elem & elem, std::unique_ptr<const Elem> & edge) const;
+  /**
+   * @returns The built edge of element \p elem when at an edge
    */
   std::unique_ptr<const Elem> build_edge(const Elem & elem) const;
 

src/geom/elem_corner.C

@@ -33,7 +33,7 @@ bool ElemCorner::at_edge(const Elem & elem, const unsigned short e) const
   return at_edge(nodes_on_edge_ptr[0], nodes_on_edge_ptr[1]);
 }
 
-std::unique_ptr<const Elem> ElemCorner::build_edge(const Elem & elem) const
+void ElemCorner::build_edge(const Elem & elem, std::unique_ptr<const Elem> & edge) const
 {
   libmesh_assert_greater(elem.dim(), 1);
   libmesh_assert(at_edge());
@@ -42,11 +42,21 @@ std::unique_ptr<const Elem> ElemCorner::build_edge(const Elem & elem) const
 
   for (const auto e : elem.edge_index_range())
     if (elem.is_node_on_edge(first, e) && elem.is_node_on_edge(second, e))
-      return elem.build_edge_ptr(e);
+    {
+      elem.build_edge_ptr(edge, e);
+      return;
+    }
 
   libmesh_error_msg("Element does not contain vertices in ElemCorner");
 }
 
+std::unique_ptr<const Elem> ElemCorner::build_edge(const Elem & elem) const
+{
+  std::unique_ptr<const Elem> edge;
+  build_edge(elem, edge);
+  return edge;
+}
+
 std::string ElemCorner::print() const
 {
   std::stringstream oss;