src/gromacs/utility/template_mp.h

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  35 /*! \libinternal \file
  36  * \brief
  37  * Declares utilities for template metaprogramming
  38  *
  39  * \author Roland Schulz <roland.schulz@intel.com>
  40  *
  41  * \inlibraryapi
  42  * \ingroup module_utility
  43  */
  44 #ifndef GMX_UTILITY_TEMPLATE_MP_H
  45 #define GMX_UTILITY_TEMPLATE_MP_H
  46
  47 #include <cassert>
  48 #include <cstddef>
  49
  50 #include <utility>
  51
  52 #include "gromacs/compat/mp11.h"
  53
  54 namespace gmx
  55 {
  56
  57 template<class Function>
  58 auto dispatchTemplatedFunction(Function&& f)
  59 {
  60     return std::forward<Function>(f)();
  61 }
  62
  63 /** \internal \brief Helper function to select appropriate template based on runtime values.
  64  *
  65  * Can only use enums for template parameters.
  66  * These enums must have a member \c Count indicating the total number of valid values.
  67  *
  68  * Example usage:
  69  * \code
  70     enum class Options {
  71         Op1 = 0,
  72         Op2 = 1,
  73         Count = 2
  74     };
  75
  76     template<Options p1, Options p2>
  77     bool foo(int i);
  78
  79     bool bar(Options p1, Options p2, int i) {
  80         return dispatchTemplatedFunction(
  81             [=](auto p1, auto p2) {
  82                 return foo<p1, p2>(i);
  83             },
  84             p1, p2);
  85     }
  86  * \endcode
  87  */
  88 template<class Function, class Enum, class... Enums>
  89 auto dispatchTemplatedFunction(Function&& f, Enum e, Enums... es)
  90 {
  91     return dispatchTemplatedFunction(
  92             [&](auto... es_) {
  93                 return compat::mp_with_index<size_t(Enum::Count)>(size_t(e), [&](auto e_) {
  94                     return std::forward<Function>(f)(
  95                             std::integral_constant<Enum, static_cast<Enum>(size_t(e_))>(), es_...);
  96                 });
  97             },
  98             es...);
  99 }
 100
 101 } // namespace gmx
 102
 103 #endif // GMX_UTILITY_TEMPLATE_MP_H