feat():initial version

install/boost_1_75_0/include/boost/histogram/weight.hpp

@@ -0,0 +1,45 @@
+// Copyright 2019 Hans Dembinski
+//
+// Distributed under the Boost Software License, Version 1.0.
+// (See accompanying file LICENSE_1_0.txt
+// or copy at http://www.boost.org/LICENSE_1_0.txt)
+
+#ifndef BOOST_HISTOGRAM_WEIGHT_HPP
+#define BOOST_HISTOGRAM_WEIGHT_HPP
+
+#include <utility>
+
+namespace boost {
+namespace histogram {
+
+/** Weight holder and type envelope.
+
+  You should not construct these directly, use the weight() helper function.
+
+  @tparam Underlying arithmetic type.
+*/
+template <class T>
+struct weight_type {
+  /// Access underlying value.
+  T value;
+
+  /// Allow implicit conversions of types when the underlying value type allows them.
+  template <class U>
+  operator weight_type<U>() const {
+    return weight_type<U>{static_cast<U>(value)};
+  }
+};
+
+/** Helper function to mark argument as weight.
+
+  @param t argument to be forward to the histogram.
+*/
+template <class T>
+auto weight(T&& t) noexcept {
+  return weight_type<T>{std::forward<T>(t)};
+}
+
+} // namespace histogram
+} // namespace boost
+
+#endif