[common] Add Dumux::NumEqVector

dumux/common/CMakeLists.txt

@@ -28,6 +28,7 @@ intersectionmapper.hh
 loggingparametertree.hh
 math.hh
 monotonecubicspline.hh
+numeqvector.hh
 numericdifferentiation.hh
 optionalscalar.hh
 parameters.hh

dumux/common/numeqvector.hh

+// -*- mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+// vi: set et ts=4 sw=4 sts=4:
+/*****************************************************************************
+ *   See the file COPYING for full copying permissions.                      *
+ *                                                                           *
+ *   This program is free software: you can redistribute it and/or modify    *
+ *   it under the terms of the GNU General Public License as published by    *
+ *   the Free Software Foundation, either version 3 of the License, or       *
+ *   (at your option) any later version.                                     *
+ *                                                                           *
+ *   This program is distributed in the hope that it will be useful,         *
+ *   but WITHOUT ANY WARRANTY; without even the implied warranty of          *
+ *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the            *
+ *   GNU General Public License for more details.                            *
+ *                                                                           *
+ *   You should have received a copy of the GNU General Public License       *
+ *   along with this program.  If not, see <http://www.gnu.org/licenses/>.   *
+ *****************************************************************************/
+/*!
+ * \file
+ * \ingroup Common
+ * \brief A helper to deduce a vector with the same size as numbers of equations
+ */
+#ifndef DUMUX_COMMON_NUMEQVECTOR_HH
+#define DUMUX_COMMON_NUMEQVECTOR_HH
+
+namespace Dumux {
+
+template<class PrimaryVariables>
+struct NumEqVectorTraits
+{
+    static constexpr std::size_t numEq = PrimaryVariables::size();
+    using type = PrimaryVariables;
+};
+
+/*!
+ * \ingroup Common
+ * \brief A vector with the same size as numbers of equations
+ * This is the default implementation and has to be specialized for
+ * all custom primary variable vector types
+ * \note This is based on the primary variables concept
+ */
+template<class PrimaryVariables>
+using NumEqVector = typename NumEqVectorTraits<PrimaryVariables>::type;
+
+} // namespace Dumux
+
+#endif