From 58b9e4085a7320f3e973d3aad754a7a999f7ee59 Mon Sep 17 00:00:00 2001
From: Andreas Fabri <andreas.fabri@geometryfactory.com>
Date: Wed, 8 Jun 2016 10:29:18 +0200
Subject: [PATCH] - ADD a macro OM_HAS_HASH in the config file. - Based on the
 macro provide partial specializations for std::hash<> - for
 vertex,halfede,edge, and face handles. - Add a free function
 hash_value(BaseHandle) for boost::unordered_set/map

---
 src/OpenMesh/Core/Mesh/Handles.hh   | 76 +++++++++++++++++++++++++++++
 src/OpenMesh/Core/Mesh/PolyMeshT.hh |  5 --
 src/OpenMesh/Core/System/config.h   |  5 ++
 3 files changed, 81 insertions(+), 5 deletions(-)

diff --git a/src/OpenMesh/Core/Mesh/Handles.hh b/src/OpenMesh/Core/Mesh/Handles.hh
index 1488ce09..94c11b70 100644
--- a/src/OpenMesh/Core/Mesh/Handles.hh
+++ b/src/OpenMesh/Core/Mesh/Handles.hh
@@ -106,6 +106,8 @@ private:
   int idx_; 
 };
 
+// this is used by boost::unordered_set/map
+inline size_t hash_value(const BaseHandle&  h)   { return h.idx(); }
 
 //-----------------------------------------------------------------------------
 
@@ -150,5 +152,79 @@ struct FaceHandle : public BaseHandle
 //=============================================================================
 } // namespace OpenMesh
 //=============================================================================
+
+#ifdef OM_HAS_HASH
+#include <functional>
+namespace std {
+
+#if defined(_MSVC_VER)
+#  pragma warning(push)
+#  pragma warning(disable:4099) // For VC++ it is class hash
+#endif
+
+
+template <>
+class hash<OpenMesh::BaseHandle >
+  : public std::unary_function<OpenMesh::BaseHandle, std::size_t>
+{
+
+  std::size_t operator()(const OpenMesh::BaseHandle& h) const
+  {
+    return h.idx();
+  }
+};
+
+template <>
+struct hash<OpenMesh::VertexHandle >
+  : public std::unary_function<OpenMesh::VertexHandle, std::size_t>
+{
+
+  std::size_t operator()(const OpenMesh::VertexHandle& h) const
+  {
+    return h.idx();
+  }
+};
+
+template <>
+struct hash<OpenMesh::HalfedgeHandle >
+  : public std::unary_function<OpenMesh::HalfedgeHandle, std::size_t>
+{
+
+  std::size_t operator()(const OpenMesh::HalfedgeHandle& h) const
+  {
+    return h.idx();
+  }
+};
+
+template <>
+struct hash<OpenMesh::EdgeHandle >
+  : public std::unary_function<OpenMesh::EdgeHandle, std::size_t>
+{
+
+  std::size_t operator()(const OpenMesh::EdgeHandle& h) const
+  {
+    return h.idx();
+  }
+};
+
+template <>
+struct hash<OpenMesh::FaceHandle >
+  : public std::unary_function<OpenMesh::FaceHandle, std::size_t>
+{
+
+  std::size_t operator()(const OpenMesh::FaceHandle& h) const
+  {
+    return h.idx();
+  }
+};
+
+#if defined(_MSVC_VER)
+#  pragma warning(pop)
+#endif
+
+}
+#endif  // OM_HAS_HASH
+
+
 #endif // OPENMESH_HANDLES_HH
 //=============================================================================
diff --git a/src/OpenMesh/Core/Mesh/PolyMeshT.hh b/src/OpenMesh/Core/Mesh/PolyMeshT.hh
index 93e40ad0..d0e4d4f8 100644
--- a/src/OpenMesh/Core/Mesh/PolyMeshT.hh
+++ b/src/OpenMesh/Core/Mesh/PolyMeshT.hh
@@ -608,11 +608,6 @@ const LHS mesh_cast(const PolyMeshT<KERNEL> *rhs) {
     return MeshCast<LHS, const PolyMeshT<KERNEL>*>::cast(rhs);
 }
 
-inline size_t hash_value(const VertexHandle&  i)   { return i.idx(); }
-inline size_t hash_value(const HalfedgeHandle&  i) { return i.idx(); }
-inline size_t hash_value(const FaceHandle&  i)     { return i.idx(); }
-
-
 //=============================================================================
 } // namespace OpenMesh
 //=============================================================================
diff --git a/src/OpenMesh/Core/System/config.h b/src/OpenMesh/Core/System/config.h
index b85d9719..31537b5e 100644
--- a/src/OpenMesh/Core/System/config.h
+++ b/src/OpenMesh/Core/System/config.h
@@ -101,6 +101,11 @@
 #endif
 
 typedef unsigned int uint;
+
+#if (_MSC_VER >= 1900 || __cplusplus > 199711L || defined(__GXX_EXPERIMENTAL_CXX0X__))
+#define OM_HAS_HASH
+#endif
+
 //=============================================================================
 #endif // OPENMESH_CONFIG_H defined
 //=============================================================================