fixes

BGL/include/CGAL/boost/graph/properties.h

@@ -123,6 +123,64 @@ using boost::face_external_index;
 namespace CGAL{
 namespace helpers {
 
+//check that an existing map is initialized/valid
+template <class PolygonMesh, class FaceIndexMap>
+bool is_face_index_map_valid(PolygonMesh& pm,
+                               FaceIndexMap& fid)
+{
+  typedef typename boost::property_traits<FaceIndexMap>::value_type Id_type;
+  const std::size_t num_f = num_faces(pm);
+  std::set<Id_type> indices;
+  for(typename boost::graph_traits<PolygonMesh>::face_descriptor fd :
+                faces(pm))
+  {
+    Id_type id = get(fid, fd);
+    if(static_cast<std::size_t>(id) >=static_cast<std::size_t>(num_f)) //also covers the case where the id is < 0 as size_t(-1) = max_int or smthg.
+      return false;
+    if(!indices.insert(id).second)
+      return false;
+  }
+  return true;
+}
+
+template <class PolygonMesh, class HalfedgeIndexMap>
+bool is_halfedge_index_map_valid(PolygonMesh& pm,
+                               HalfedgeIndexMap& fid)
+{
+  typedef typename boost::property_traits<HalfedgeIndexMap>::value_type Id_type;
+  const std::size_t num_hd = num_halfedges(pm);
+  std::set<Id_type> indices;
+  for(typename boost::graph_traits<PolygonMesh>::halfedge_descriptor hd :
+                halfedges(pm))
+  {
+    Id_type id = get(fid, hd);
+    if(static_cast<std::size_t>(id) >=static_cast<std::size_t>(num_hd)) //also covers the case where the id is < 0 as size_t(-1) = max_int or smthg.
+      return false;
+    if(!indices.insert(id).second)
+      return false;
+  }
+  return true;
+}
+
+template <class PolygonMesh, class VertexIndexMap>
+bool is_vertex_index_map_valid(PolygonMesh& pm,
+                               VertexIndexMap& fid)
+{
+  typedef typename boost::property_traits<VertexIndexMap>::value_type Id_type;
+  const std::size_t num_v= num_vertices(pm);
+  std::set<Id_type> indices;
+  for(typename boost::graph_traits<PolygonMesh>::vertex_descriptor vd :
+                vertices(pm))
+  {
+    Id_type id = get(fid, vd);
+    if(static_cast<std::size_t>(id) >=static_cast<std::size_t>(num_v)) //also covers the case where the id is < 0 as size_t(-1) = max_int or smthg.
+      return false;
+    if(!indices.insert(id).second)
+      return false;
+  }
+  return true;
+}
+
 // matches read-write property maps
 template <class PolygonMesh, class FaceIndexMap, class Tag>
 void init_face_indices(PolygonMesh& pm,
@@ -130,6 +188,8 @@ void init_face_indices(PolygonMesh& pm,
                        boost::read_write_property_map_tag,
                        Tag)
 {
+  if(is_face_index_map_valid(pm, fid))
+    return;
   typename boost::property_traits<FaceIndexMap>::value_type i = 0;
   for(typename boost::graph_traits<PolygonMesh>::face_descriptor fd :
                 faces(pm))
@@ -144,6 +204,8 @@ void init_vertex_indices(PolygonMesh& pm,
                          boost::read_write_property_map_tag,
                          Tag)
 {
+  if(is_vertex_index_map_valid(pm, vid))
+    return;
   typename boost::property_traits<VertexIndexMap>::value_type i = 0;
   for(typename boost::graph_traits<PolygonMesh>::vertex_descriptor vd :
                 vertices(pm))
@@ -158,6 +220,8 @@ void init_halfedge_indices(PolygonMesh& pm,
                            boost::read_write_property_map_tag,
                            Tag)
 {
+  if(is_halfedge_index_map_valid(pm, hid))
+    return;
   typename boost::property_traits<HalfedgeIndexMap>::value_type i = 0;
   for(typename boost::graph_traits<PolygonMesh>::halfedge_descriptor hd :
                 halfedges(pm))

Polygon_mesh_processing/include/CGAL/Polygon_mesh_processing/border.h

@@ -152,7 +152,7 @@ namespace Polygon_mesh_processing {
   * but `face(h, pmesh)` does not belong to the patch.
   *
   * @tparam PolygonMesh model of `HalfedgeGraph`. If `PolygonMesh`
-  *  has an internal not writable property map
+  *  has an internal non mutable property map
   *  for `CGAL::face_index_t` and no `face_index_map` is given
   *  as a named parameter, then the internal one must be initialized; else, it will be.
   * @tparam FaceRange range of