boost/histogram/weight.hpp

0001 // Copyright 2019 Hans Dembinski
0002 //
0003 // Distributed under the Boost Software License, Version 1.0.
0004 // (See accompanying file LICENSE_1_0.txt
0005 // or copy at http://www.boost.org/LICENSE_1_0.txt)
0006
0007 #ifndef BOOST_HISTOGRAM_WEIGHT_HPP
0008 #define BOOST_HISTOGRAM_WEIGHT_HPP
0009
0010 #include <utility>
0011
0012 namespace boost {
0013 namespace histogram {
0014
0015 /** Weight holder and type envelope.
0016
0017   You should not construct these directly, use the weight() helper function.
0018
0019   @tparam Underlying arithmetic type.
0020 */
0021 template <class T>
0022 struct weight_type {
0023   /// Access underlying value.
0024   T value;
0025
0026   /// Allow implicit conversions of types when the underlying value type allows them.
0027   template <class U>
0028   operator weight_type<U>() const {
0029     return weight_type<U>{static_cast<U>(value)};
0030   }
0031 };
0032
0033 /** Helper function to mark argument as weight.
0034
0035   @param t argument to be forward to the histogram.
0036 */
0037 template <class T>
0038 auto weight(T&& t) noexcept {
0039   return weight_type<T>{std::forward<T>(t)};
0040 }
0041
0042 } // namespace histogram
0043 } // namespace boost
0044
0045 #endif