From bf0e52cf6e73cd5fb89b17b57d162cff9cf383da Mon Sep 17 00:00:00 2001
From: Maxime Gimeno <maxime.gimeno@gmail.com>
Date: Tue, 24 Sep 2019 16:36:57 +0200
Subject: [PATCH] Incorporate the initialization of the map to the helpers.

---
 .../CGAL/boost/graph/named_params_helper.h    | 103 ++++++++++++++----
 .../connected_components.h                    |  12 +-
 2 files changed, 82 insertions(+), 33 deletions(-)

diff --git a/BGL/include/CGAL/boost/graph/named_params_helper.h b/BGL/include/CGAL/boost/graph/named_params_helper.h
index 1a1639f0209..37f8a1f0b78 100644
--- a/BGL/include/CGAL/boost/graph/named_params_helper.h
+++ b/BGL/include/CGAL/boost/graph/named_params_helper.h
@@ -115,49 +115,106 @@ namespace CGAL {
 
   namespace internal_np
   {
+  template<typename key_value, class PMap, class Graph, typename Tag>
+  struct MapInitializer{
+    void operator()(PMap, const Graph& )
+    {}
+  };
+
+  template<typename key_value, class PMap, class Graph>
+  struct MapInitializer<key_value, PMap, Graph, CGAL::Tag_false>{
+    void operator()( PMap, const Graph& )
+    {
+      //do nothing.
+    }
+  };
+
+  template< class PMap, class Graph>
+  struct MapInitializer<
+      typename boost::graph_traits<Graph>::vertex_descriptor,
+      PMap, Graph,
+      CGAL::Tag_true>{
+    void operator()(PMap map, const Graph& g)
+    {
+      CGAL::helpers::init_vertex_indices(g, map);
+    }
+  };
+
+  template< class PMap, class Graph>
+  struct MapInitializer<
+      typename boost::graph_traits<Graph>::halfedge_descriptor,
+      PMap, Graph,
+      CGAL::Tag_true>{
+    void operator()(PMap map, const Graph& g)
+    {
+      CGAL::helpers::init_halfedge_indices(g, map);
+    }
+  };
+
+  template< class PMap, class Graph>
+  struct MapInitializer<
+      typename boost::graph_traits<Graph>::face_descriptor,
+      PMap, Graph,
+      CGAL::Tag_true>{
+    void operator()(PMap map,const Graph& g)
+    {
+      CGAL::helpers::init_face_indices(g, map);
+    }
+  };
 
   template<typename PMapCategory>
-  bool is_pmap_writable(PMapCategory)
-  {
-    return false;
-  }
+  struct Is_pmap_writable{
+    typedef CGAL::Tag_false result;
+  };
+
   template<>
-  bool is_pmap_writable(boost::read_write_property_map_tag)
-  {
-    return true;
-  }
+  struct Is_pmap_writable<boost::read_write_property_map_tag>{
+    typedef CGAL::Tag_true result;
+  };
+
   template<>
-  bool is_pmap_writable(boost::writable_property_map_tag)
-  {
-    return true;
-  }
+  struct Is_pmap_writable<boost::writable_property_map_tag>{
+    typedef CGAL::Tag_true result;
+  };
   //overloads used to select a default map:
   // use the one passed in the named parameters (user must have initialized it)
   template <class MapFromNP, class Default_tag, class Dynamic_tag, class Mesh>
   MapFromNP
-  get_map(MapFromNP m, Default_tag, Dynamic_tag, const Mesh&, bool& need_init)
+  get_map(MapFromNP m, Default_tag, Dynamic_tag, const Mesh&)
   {
-    need_init = false;
     return m;
   }
 
   // use the one internal to the mesh (user must have initialized it)
   template <class Default_tag, class Dynamic_tag, class Mesh>
   typename boost::property_map<Mesh, Default_tag >::const_type
-  get_map(CGAL::internal_np::Param_not_found, Default_tag t, Dynamic_tag , const Mesh& m, bool& need_init)
+  get_map(CGAL::internal_np::Param_not_found, Default_tag t, Dynamic_tag , const Mesh& m)
   {
-    need_init = is_pmap_writable(typename boost::property_traits<typename boost::property_map<Mesh, Default_tag >::const_type>::category());
-    return get(t,m);
+    typename boost::property_map<Mesh, Default_tag >::const_type map = get(t, m);
+    MapInitializer<
+        typename boost::property_traits<typename boost::property_map<Mesh, Default_tag >::const_type>::key_type,
+        typename boost::property_map<Mesh, Default_tag >::const_type,
+        Mesh,
+        typename Is_pmap_writable<
+        typename boost::property_traits
+        <typename boost::property_map<Mesh, Default_tag >
+        ::const_type>::category>::result>
+        ()(map, m);
+    return map;
   }
 
   // create a dynamic property and initialize it
   template <class Dynamic_tag, class Mesh>
   typename boost::property_map<Mesh, Dynamic_tag >::const_type
-  get_map(CGAL::internal_np::Param_not_found, Dynamic_tag t, Dynamic_tag , const Mesh& m, bool& need_init)
+  get_map(CGAL::internal_np::Param_not_found, Dynamic_tag t, Dynamic_tag , const Mesh& m)
   {
-
-    need_init = true;
-    return get(t,m);
+    typename boost::property_map<Mesh, Dynamic_tag >::const_type map = get(t,m);
+    MapInitializer<
+        typename boost::property_traits<typename boost::property_map<Mesh, Dynamic_tag >::const_type>::key_type,
+        typename boost::property_map<Mesh, Dynamic_tag >::const_type,
+        Mesh,
+        CGAL::Tag_true>()(map, m);
+    return map;
   }
 
   }//end of internal_np
@@ -197,13 +254,13 @@ namespace CGAL {
       : dtag(dtag), m(m), np(np), p(p) {}
 
 
-    PropertyMapType property_map(bool& need_init)
+    PropertyMapType property_map()
     {
       return internal_np::get_map(
             parameters::get_parameter(np, p),
             Final_tag(),
             dtag,
-            m, need_init);
+            m);
     }
   };
 
diff --git a/Polygon_mesh_processing/include/CGAL/Polygon_mesh_processing/connected_components.h b/Polygon_mesh_processing/include/CGAL/Polygon_mesh_processing/connected_components.h
index 72c9c708dc0..d80320ce963 100644
--- a/Polygon_mesh_processing/include/CGAL/Polygon_mesh_processing/connected_components.h
+++ b/Polygon_mesh_processing/include/CGAL/Polygon_mesh_processing/connected_components.h
@@ -240,11 +240,7 @@ connected_components(const PolygonMesh& pmesh,
                     CGAL::dynamic_face_property_t<int>(),
                     pmesh, np, internal_np::face_index);
 
-  bool need_init;
-  typename MapGetter::PropertyMapType fimap = get_map.property_map(need_init);
-  if(need_init)
-    CGAL::helpers::init_face_indices(pmesh, fimap);
-
+  typename MapGetter::PropertyMapType fimap = get_map.property_map();
   return boost::connected_components(finite_dual,
     fcm,
     boost::vertex_index_map(fimap)
@@ -327,11 +323,7 @@ std::size_t keep_largest_connected_components(PolygonMesh& pmesh,
                     CGAL::dynamic_face_property_t<int>(),
                     pmesh, np, internal_np::face_index);
 
-  bool need_init;
-  FaceIndexMap fimap = get_map.property_map(need_init);
-  if(need_init)
-    CGAL::helpers::init_face_indices(pmesh, fimap);
-
+  FaceIndexMap fimap = get_map.property_map();
   // FaceSizeMap
   typedef typename internal_np::Lookup_named_param_def<internal_np::face_size_map_t,
                                                  NamedParameters,