shortest path queries always return the source point and distance

Surface_mesh_shortest_path/doc/Surface_mesh_shortest_path/PackageDescription.txt

@@ -10,7 +10,6 @@
 
 /*!
 \addtogroup PkgSurfaceMeshShortestPath
-\todo shall all queries return the distance and the shortest path, potentially using boost::optional? Think about update the user manual
 \todo Modify the algorithm to support more efficient incremental construction
 \todo Add parallelization to the algorithm
 \todo Add methods for computing the ridge tree using the output of the algorithm

Surface_mesh_shortest_path/include/CGAL/Surface_mesh_shortest_path/Surface_mesh_shortest_path.h

@@ -2321,24 +2321,29 @@ public:
   
   \param v A vertex of the input face graph
   \param visitor A model of `SurfaceMeshShortestPathVisitor` to receive the shortest path
-  \return true if there exists a shortest path from `v` to any source point, false otherwise (may occur if the input face graph is disconnected)
+  \return A pair, containing the distance to the source point, and an 
+    iterator to the source point.  If no source point was reachable (can
+    occur when the graph is disconnected), the distance will be a negative 
+    value and the source point iterator will be equal to `source_points_end()`.
   */
   template <class Visitor>
-  bool shortest_path_sequence_to_source_points(vertex_descriptor v, Visitor& visitor)
+  Shortest_path_result
+  shortest_path_sequence_to_source_points(vertex_descriptor v, Visitor& visitor)
   {
     build_sequence_tree();
     
-    Cone_tree_node* current = m_closestToVertices[get(m_vertexIndexMap, v)].first;
+    Node_distance_pair result = m_closestToVertices[get(m_vertexIndexMap, v)];
+    Cone_tree_node* current = result.first;
     
     if (current)
     {
       visitor(v);
       visit_shortest_path(current, current->target_point(), visitor);
-      return true;
+      return std::make_pair(result.second, m_rootNodes[current->tree_id()].second);
     }
     else
     {
-      return false;
+      return std::make_pair(FT(-1.0), source_points_end());
     }
   }
   
@@ -2354,10 +2359,14 @@ public:
   \param f A face of the input face graph
   \param location Barycentric coordinate of the query point on face `f`
   \param visitor A model of `SurfaceMeshShortestPathVisitor` to receive the shortest path
-  \return true if there exists a shortest path from the query point to any source point, false otherwise (may occur if the input face graph is disconnected)
+  \return A pair, containing the distance to the source point, and an 
+    iterator to the source point.  If no source point was reachable (can
+    occur when the graph is disconnected), the distance will be a negative 
+    value and the source point iterator will be equal to `source_points_end()`.
   */
   template <class Visitor>
-  bool shortest_path_sequence_to_source_points(face_descriptor f, Barycentric_coordinate location, Visitor& visitor)
+  Shortest_path_result
+  shortest_path_sequence_to_source_points(face_descriptor f, Barycentric_coordinate location, Visitor& visitor)
   {
     build_sequence_tree();
     
@@ -2369,11 +2378,11 @@ public:
       Point_2 locationInContext = construct_barycenter_in_triangle_2(current->layout_face(), result.second);
       visitor(f, location);
       visit_shortest_path(current, locationInContext, visitor);
-      return true;
+      return std::make_pair(result.first.second, m_rootNodes[current->tree_id()].second);
     }
     else
     {
-      return false;
+      return std::make_pair(FT(-1.0), source_points_end());
     }
   }
   
@@ -2389,10 +2398,14 @@ public:
   
   \param v A vertex of the input face graph
   \param output An OutputIterator to receive the shortest path points as `Point_3` objects
-  \return true if there exists a shortest path to v, false otherwise (may occur if the input face graph is disconnected)
+  \return A pair, containing the distance to the source point, and an 
+    iterator to the source point.  If no source point was reachable (can
+    occur when the graph is disconnected), the distance will be a negative 
+    value and the source point iterator will be equal to `source_points_end()`.
   */
   template <class OutputIterator>
-  bool shortest_path_points_to_source_points(vertex_descriptor v, OutputIterator output)
+  Shortest_path_result
+  shortest_path_points_to_source_points(vertex_descriptor v, OutputIterator output)
   {
     build_sequence_tree();
     
@@ -2408,10 +2421,14 @@ public:
   \param f A face of on the input face graph
   \param location The barycentric coordinate of the query point on face `f` 
   \param output An OutputIterator to receive the shortest path points as `Point_3` objects
-  \return true if there exists a shortest path to the query point, false otherwise (may occur if the input face graph is disconnected)
+  \return A pair, containing the distance to the source point, and an 
+    iterator to the source point.  If no source point was reachable (can
+    occur when the graph is disconnected), the distance will be a negative 
+    value and the source point iterator will be equal to `source_points_end()`.
   */
   template <class OutputIterator>
-  bool shortest_path_points_to_source_points(face_descriptor f, Barycentric_coordinate location, OutputIterator output)
+  Shortest_path_result
+  shortest_path_points_to_source_points(face_descriptor f, Barycentric_coordinate location, OutputIterator output)
   {
     build_sequence_tree();