[histv7] Simplify class structure:

hist/histv7/inc/ROOT/RAxisLayout.hxx

@@ -0,0 +1,62 @@
+/// \file ROOT/RAxisLayout.h
+/// \ingroup Hist ROOT7
+/// \author Axel Naumann <axel@cern.ch>
+/// \date 2020-07-06
+/// \warning This is part of the ROOT 7 prototype! It will change without notice. It might trigger earthquakes. Feedback
+/// is welcome!
+
+/*************************************************************************
+ * Copyright (C) 1995-2020, Rene Brun and Fons Rademakers.               *
+ * All rights reserved.                                                  *
+ *                                                                       *
+ * For the licensing terms see $ROOTSYS/LICENSE.                         *
+ * For the list of contributors see $ROOTSYS/README/CREDITS.             *
+ *************************************************************************/
+
+#ifndef ROOT7_RAxisLayout
+#define ROOT7_RAxisLayout
+
+#include <string>
+#include <utility>
+#include <vector>
+
+namespace ROOT {
+namespace Experimental {
+namespace Internal {
+
+/**
+\class RAxisLayout
+Calculuates bin index from a set of axes and a coordinate tuple.
+*/
+template <class AxisTuple>
+class RAxisLayout {
+private:
+   ///\{
+   /// Internal types to translate tuple<AXES...> => tuple<AXES::Coord_t...>
+   template <class T>
+   struct CoordTuple;
+
+   template <class... Axes>
+   struct CoordTuple<std::tuple<Axes...>> {
+      using type = std::tuple<typename Axes::Coord_t...>;
+   };
+   ///\}
+
+public:
+   using AxisTuple_t = AxisTuple;
+   using CoordTuple_t = typename CoordTuple<AxisTuple>::type;
+
+private:
+   AxisTuple fAxes;
+
+public:
+   RAxisLayout(const AxisTuple &axes): fAxes(axes) {}
+
+   ssize_t GetBinIndex(const CoordTuple_t &x) const;
+};
+
+} // namespace Internal
+} // namespace Experimental
+} // namespace ROOT
+
+#endif // ROOT7_RAxisLayout header guard