make is_polymesh / is_trimesh methods constexpr and add a ConnectivityTag typedef to help with tag dispatching

src/OpenMesh/Core/Mesh/PolyMeshT.hh

@@ -65,6 +65,7 @@
 #include <OpenMesh/Core/Geometry/MathDefs.hh>
 #include <OpenMesh/Core/Mesh/PolyConnectivity.hh>
 #include <OpenMesh/Core/Mesh/FinalMeshItemsT.hh>
+#include <OpenMesh/Core/Mesh/Tags.hh>
 #include <vector>
 
 
@@ -100,11 +101,12 @@ public:
   //--- item types ---
 
   //@{
-  /// Determine whether this is a PolyMeshT or TriMeshT ( This function does not check the per face vertex count! It only checks if the datatype is PolyMeshT or TriMeshT )
+  /// Determine whether this is a PolyMeshT or TriMeshT (This function does not check the per face vertex count! It only checks if the datatype is PolyMeshT or TriMeshT)
+  static constexpr bool is_polymesh() { return true;  }
+  static constexpr bool is_trimesh()  { return false; }
+  using ConnectivityTag = TriConnectivityTag;
   enum { IsPolyMesh = 1 };
   enum { IsTriMesh  = 0 };
-  static bool is_polymesh() { return true;  }
-  static bool is_trimesh()  { return false; }
   //@}
 
   /// \name Mesh Items

src/OpenMesh/Core/Mesh/Tags.hh

@@ -0,0 +1,54 @@
+/* ========================================================================= *
+ *                                                                           *
+ *                               OpenMesh                                    *
+ *           Copyright (c) 2001-2015, RWTH-Aachen University                 *
+ *           Department of Computer Graphics and Multimedia                  *
+ *                          All rights reserved.                             *
+ *                            www.openmesh.org                               *
+ *                                                                           *
+ *---------------------------------------------------------------------------*
+ * This file is part of OpenMesh.                                            *
+ *---------------------------------------------------------------------------*
+ *                                                                           *
+ * Redistribution and use in source and binary forms, with or without        *
+ * modification, are permitted provided that the following conditions        *
+ * are met:                                                                  *
+ *                                                                           *
+ * 1. Redistributions of source code must retain the above copyright notice, *
+ *    this list of conditions and the following disclaimer.                  *
+ *                                                                           *
+ * 2. Redistributions in binary form must reproduce the above copyright      *
+ *    notice, this list of conditions and the following disclaimer in the    *
+ *    documentation and/or other materials provided with the distribution.   *
+ *                                                                           *
+ * 3. Neither the name of the copyright holder nor the names of its          *
+ *    contributors may be used to endorse or promote products derived from   *
+ *    this software without specific prior written permission.               *
+ *                                                                           *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS       *
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED *
+ * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A           *
+ * PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER *
+ * OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,  *
+ * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,       *
+ * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR        *
+ * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF    *
+ * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING      *
+ * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS        *
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.              *
+ *                                                                           *
+ * ========================================================================= */
+
+#ifndef OPENMESH_TAGS_HH
+#define OPENMESH_TAGS_HH
+
+namespace OpenMesh {
+
+/// Connectivity tag indicating that the tagged mesh has polygon connectivity.
+struct PolyConnectivityTag {};
+/// Connectivity tag indicating that the tagged mesh has triangle connectivity.
+struct TriConnectivityTag {};
+
+} // namespace OpenMesh
+
+#endif

src/OpenMesh/Core/Mesh/TriMeshT.hh

@@ -63,6 +63,7 @@
 
 #include <OpenMesh/Core/System/config.h>
 #include <OpenMesh/Core/Mesh/PolyMeshT.hh>
+#include <OpenMesh/Core/Mesh/Tags.hh>
 #include <vector>
 
 
@@ -103,11 +104,12 @@ public:
   typedef PolyMeshT<Kernel>                     PolyMesh;
 
   //@{
-  /// Determine whether this is a PolyMeshT or TriMeshT ( This function does not check the per face vertex count! It only checks if the datatype is PolyMeshT or TriMeshT )
+  /// Determine whether this is a PolyMeshT or TriMeshT (This function does not check the per face vertex count! It only checks if the datatype is PolyMeshT or TriMeshT)
+  static constexpr bool is_polymesh() { return false; }
+  static constexpr bool is_trimesh()  { return true;  }
+  using ConnectivityTag = TriConnectivityTag;
   enum { IsPolyMesh = 0 };
   enum { IsTriMesh  = 1 };
-  static bool is_polymesh() { return false; }
-  static bool is_trimesh()  { return  true; }
   //@}
 
   //--- items ---