ceph/src/boost/boost/histogram/weight.hpp

   1 // Copyright 2019 Hans Dembinski
   2 //
   3 // Distributed under the Boost Software License, Version 1.0.
   4 // (See accompanying file LICENSE_1_0.txt
   5 // or copy at http://www.boost.org/LICENSE_1_0.txt)
   6
   7 #ifndef BOOST_HISTOGRAM_WEIGHT_HPP
   8 #define BOOST_HISTOGRAM_WEIGHT_HPP
   9
  10 #include <utility>
  11
  12 namespace boost {
  13 namespace histogram {
  14
  15 /** Weight holder and type envelope.
  16
  17   You should not construct these directly, use the weight() helper function.
  18
  19   @tparam Underlying arithmetic type.
  20 */
  21 template <class T>
  22 struct weight_type {
  23   /// Access underlying value.
  24   T value;
  25
  26   /// Allow implicit conversions of types when the underlying value type allows them.
  27   template <class U>
  28   operator weight_type<U>() const {
  29     return weight_type<U>{static_cast<U>(value)};
  30   }
  31 };
  32
  33 /** Helper function to mark argument as weight.
  34
  35   @param t argument to be forward to the histogram.
  36 */
  37 template <class T>
  38 auto weight(T&& t) noexcept {
  39   return weight_type<T>{std::forward<T>(t)};
  40 }
  41
  42 } // namespace histogram
  43 } // namespace boost
  44
  45 #endif