feat():initial version

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

@@ -0,0 +1,33 @@
+// Copyright 2015-2017 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_LITERALS_HPP
+#define BOOST_HISTOGRAM_LITERALS_HPP
+
+#include <type_traits>
+
+namespace boost {
+namespace histogram {
+namespace detail {
+constexpr unsigned parse_number(unsigned n) { return n; }
+
+template <class... Rest>
+constexpr unsigned parse_number(unsigned n, char f, Rest... rest) {
+  return parse_number(10u * n + static_cast<unsigned>(f - '0'), rest...);
+}
+} // namespace detail
+
+namespace literals {
+/// Suffix operator to generate literal compile-time numbers, 0_c, 12_c, etc.
+template <char... digits>
+auto operator"" _c() {
+  return std::integral_constant<unsigned, detail::parse_number(0, digits...)>();
+}
+} // namespace literals
+} // namespace histogram
+} // namespace boost
+
+#endif