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Diffstat (limited to 'boost/hana/comparing.hpp')
-rw-r--r-- | boost/hana/comparing.hpp | 45 |
1 files changed, 45 insertions, 0 deletions
diff --git a/boost/hana/comparing.hpp b/boost/hana/comparing.hpp new file mode 100644 index 0000000000..7b8bf28407 --- /dev/null +++ b/boost/hana/comparing.hpp @@ -0,0 +1,45 @@ +/*! +@file +Defines `boost::hana::comparing`. + +@copyright Louis Dionne 2013-2016 +Distributed under the Boost Software License, Version 1.0. +(See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt) + */ + +#ifndef BOOST_HANA_COMPARING_HPP +#define BOOST_HANA_COMPARING_HPP + +#include <boost/hana/fwd/comparing.hpp> + +#include <boost/hana/config.hpp> +#include <boost/hana/equal.hpp> + +#include <type_traits> + + +BOOST_HANA_NAMESPACE_BEGIN + namespace detail { + template <typename F> + struct equal_by { + F f; + + template <typename X, typename Y> + constexpr auto operator()(X&& x, Y&& y) const& + { return hana::equal(f(static_cast<X&&>(x)), f(static_cast<Y&&>(y))); } + + template <typename X, typename Y> + constexpr auto operator()(X&& x, Y&& y) & + { return hana::equal(f(static_cast<X&&>(x)), f(static_cast<Y&&>(y))); } + }; + } + + //! @cond + template <typename F> + constexpr auto comparing_t::operator()(F&& f) const { + return detail::equal_by<typename std::decay<F>::type>{static_cast<F&&>(f)}; + } + //! @endcond +BOOST_HANA_NAMESPACE_END + +#endif // !BOOST_HANA_COMPARING_HPP |