From d84be563f8ca49723865390496de4b3485f11851 Mon Sep 17 00:00:00 2001
From: Andreas Fabri <andreas.fabri@geometryfactory.com>
Date: Mon, 6 Jun 2016 19:10:58 +0200
Subject: [PATCH] Add hash_value and specialization of hash for OpenMesh

---
 .../BGL_polyhedron_3/copy_polyhedron.cpp      |  7 --
 .../graph_traits_PolyMesh_ArrayKernelT.h      |  4 +-
 .../graph/graph_traits_TriMesh_ArrayKernelT.h |  2 +
 .../doc/STL_Extension/Concepts/Hashable.h     |  4 +-
 STL_Extension/include/CGAL/hash_openmesh.h    | 64 +++++++++++++++++++
 5 files changed, 71 insertions(+), 10 deletions(-)
 create mode 100644 STL_Extension/include/CGAL/hash_openmesh.h

diff --git a/BGL/examples/BGL_polyhedron_3/copy_polyhedron.cpp b/BGL/examples/BGL_polyhedron_3/copy_polyhedron.cpp
index 1092d2b5ef2..3695a0fa227 100644
--- a/BGL/examples/BGL_polyhedron_3/copy_polyhedron.cpp
+++ b/BGL/examples/BGL_polyhedron_3/copy_polyhedron.cpp
@@ -12,13 +12,6 @@
 #include <OpenMesh/Core/IO/MeshIO.hh>
 #include <OpenMesh/Core/Mesh/PolyMesh_ArrayKernelT.hh>
 #include <CGAL/boost/graph/graph_traits_PolyMesh_ArrayKernelT.h>
-
-namespace OpenMesh { // auxiliary functions so OpenMesh Handles can be hashed
-inline std::size_t hash_value(const VertexHandle&  i) { return i.idx(); }
-inline std::size_t hash_value(const HalfedgeHandle&  i) { return i.idx(); }
-inline std::size_t hash_value(const FaceHandle&  i) { return i.idx(); }
-}
-
 #endif
 
 #include <CGAL/boost/graph/copy_face_graph.h>
diff --git a/BGL/include/CGAL/boost/graph/graph_traits_PolyMesh_ArrayKernelT.h b/BGL/include/CGAL/boost/graph/graph_traits_PolyMesh_ArrayKernelT.h
index ff8ddf22cf6..c8036b06b93 100644
--- a/BGL/include/CGAL/boost/graph/graph_traits_PolyMesh_ArrayKernelT.h
+++ b/BGL/include/CGAL/boost/graph/graph_traits_PolyMesh_ArrayKernelT.h
@@ -37,6 +37,8 @@
 
 #include <OpenMesh/Core/Mesh/PolyMesh_ArrayKernelT.hh>
 
+#include <CGAL/hash_openmesh.h>
+
 // http://openmesh.org/Documentation/OpenMesh-Doc-Latest/classOpenMesh_1_1Concepts_1_1KernelT.html
 
 #if defined(BOOST_MSVC)
@@ -672,8 +674,6 @@ void clear(OpenMesh::PolyMesh_ArrayKernelT<K>& sm)
 }
 
 }
-
-
 #ifndef CGAL_NO_DEPRECATED_CODE
 #include <CGAL/boost/graph/backward_compatibility_functions.h>
 
diff --git a/BGL/include/CGAL/boost/graph/graph_traits_TriMesh_ArrayKernelT.h b/BGL/include/CGAL/boost/graph/graph_traits_TriMesh_ArrayKernelT.h
index 53e6a5754f4..fad7d6698d6 100644
--- a/BGL/include/CGAL/boost/graph/graph_traits_TriMesh_ArrayKernelT.h
+++ b/BGL/include/CGAL/boost/graph/graph_traits_TriMesh_ArrayKernelT.h
@@ -35,6 +35,8 @@
 
 #include <OpenMesh/Core/Mesh/TriMesh_ArrayKernelT.hh>
 
+#include <CGAL/hash_openmesh.h>
+
 // http://openmesh.org/Documentation/OpenMesh-Doc-Latest/classOpenMesh_1_1Concepts_1_1KernelT.html
 
 #if defined(BOOST_MSVC)
diff --git a/STL_Extension/doc/STL_Extension/Concepts/Hashable.h b/STL_Extension/doc/STL_Extension/Concepts/Hashable.h
index c5d6e51c292..0c9d436c1f2 100644
--- a/STL_Extension/doc/STL_Extension/Concepts/Hashable.h
+++ b/STL_Extension/doc/STL_Extension/Concepts/Hashable.h
@@ -7,7 +7,9 @@ A type `Key` is a model of the concept `Hashable` if the
 specializations `boost::hash<Key>` and `std::hash<Key>` exist. 
 
 \cgalHasModel All handles and indices of \cgal data structures.
-
+\cgalHasModel All handles of OpenMesh, by including the specializations 
+of the `graph_traits` header files provided by \cgal.
+They can be disables by defining the macro `CGAL_DISABLE_HASH_OPENMESH`.
 
 \sa `CGAL::Unique_hash_map<Key,Mapped,Hash>` 
 \sa <A HREF="http://www.cplusplus.com/reference/unordered_set/unordered_set/">`std::unordered_set`</a>
diff --git a/STL_Extension/include/CGAL/hash_openmesh.h b/STL_Extension/include/CGAL/hash_openmesh.h
new file mode 100644
index 00000000000..757c08b91ea
--- /dev/null
+++ b/STL_Extension/include/CGAL/hash_openmesh.h
@@ -0,0 +1,64 @@
+// 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)     : Andreas Fabri
+
+#ifndef CGAL_HASH_OPENMESH_H
+#define CGAL_HASH_OPENMESH_H
+
+
+#ifndef CGAL_DISABLE_HASH_OPENMESH
+
+#include <functional>
+#include <OpenMesh/Core/Mesh/Handles.hh>
+namespace OpenMesh {
+
+inline std::size_t hash_value(const BaseHandle& h) { return h.idx(); }
+
+} // namespace OpenMesh
+
+namespace std {
+
+#if defined(BOOST_MSVC)
+#  pragma warning(push)
+#  pragma warning(disable:4099) // For VC10 it is class hash 
+#endif
+
+#ifndef CGAL_CFG_NO_STD_HASH
+
+  template <>
+  struct hash<OpenMesh::BaseHandle >
+    : public std::unary_function<OpenMesh::BaseHandle, std::size_t> 
+  {
+
+    std::size_t operator()(const OpenMesh::BaseHandle& h) const
+    {
+      return h.idx();
+    }
+  };
+#endif // CGAL_CFG_NO_STD_HASH
+
+#if defined(BOOST_MSVC)
+#  pragma warning(pop)
+#endif
+
+} // namespace std
+
+#endif // CGAL_DISABLE_HASH_OPENMESH
+
+
+#endif // CGAL_HASH_OPENMESH_H