Add reserve(G, nv, ne, nf)

BGL/doc/BGL/PackageDescription.txt

@@ -157,6 +157,7 @@ user might encounter.
 
 - `CGAL::clear()`
 - `CGAL::copy_face_graph()`
+- `CGAL::reserve()`
 
 ## Iterators ##
 - `CGAL::Halfedge_around_source_iterator`

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

@@ -25,6 +25,7 @@
 #include <CGAL/boost/graph/iterator.h>
 #include <CGAL/boost/graph/properties.h>
 #include <CGAL/boost/graph/internal/Has_member_clear.h>
+#include <CGAL/boost/graph/internal/Has_member_reserve.h>
 
 namespace CGAL {
 
@@ -725,6 +726,21 @@ clear_impl(FaceGraph& g)
   }
 }
 
+
+template<typename FaceGraph, typename T>
+inline
+typename boost::enable_if<Has_member_reserve<FaceGraph,T>, void>::type
+reserve_impl(FaceGraph& g, T nv, T ne, T nf)
+{
+  g.reserve();
+}
+
+template<typename FaceGraph, typename T>
+inline
+typename boost::disable_if<Has_member_reserve<FaceGraph,T>, void>::type
+reserve_impl(FaceGraph& g, T, T, T)
+{}
+
 }
 
 /**
@@ -752,6 +768,26 @@ void clear(FaceGraph& g)
 }
 
 
+/**
+ * \ingroup PkgBGLHelperFct
+ *
+ * If the graph has a member function `reserve()`, it will be called.
+ * 
+ * @tparam FaceGraph model of `MutableHalfedgeGraph` and `MutableFaceGraph`
+ *
+ * @param g the graph
+ * @param nv number of vertices
+ * @param ne number of edges
+ * @param nf number of faces
+ *
+ **/
+template<typename FaceGraph, typename T>
+void reserve(FaceGraph& g, T nv, T ne, T nf)
+{
+  internal::reserve_impl(g,nv, ne, nf);
+}
+
+
 } // namespace CGAL
 
 // Include "Euler_operations.h" at the end, because its implementation

BGL/include/CGAL/boost/graph/internal/Has_member_reserve.h

@@ -0,0 +1,45 @@
+// Copyright (c) 2016 GeometryFactory (France).  All rights reserved.
+//
+// This file is part of CGAL (www.cgal.org); you can redistribute it and/or
+// modify it under the terms of the GNU Lesser General Public License as
+// published by the Free Software Foundation; either version 3 of the License,
+// or (at your option) any later version.
+//
+// Licensees holding a valid commercial license may use this file in
+// accordance with the commercial license agreement provided with the software.
+//
+// This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
+// WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
+//
+// $URL$
+// $Id$
+//
+// Author(s) : Sebastien Loriot
+
+
+#ifndef CGAL_HAS_MEMBER_RESERVE_H
+#define CGAL_HAS_MEMBER_RESERVE_H
+
+namespace CGAL {
+namespace internal {
+
+template<class T>
+class Has_member_reserve
+{
+private:
+  template<class U, U>
+  class check {};
+
+  template<class C>
+  static char f(check<void(C::*)(void), &C::reserve>*);
+
+  template<class C>
+  static int f(...);
+public:
+  static const bool value = (sizeof(f<T>(0)) == sizeof(char));
+};
+
+}  // internal
+}  // CGAL
+
+#endif /* CGAL_HAS_MEMBER_RESERVE_H */