/*! @file Defines `boost::hana::less_equal`. @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_LESS_EQUAL_HPP #define BOOST_HANA_LESS_EQUAL_HPP #include <boost/hana/fwd/less_equal.hpp> #include <boost/hana/concept/orderable.hpp> #include <boost/hana/config.hpp> #include <boost/hana/core/common.hpp> #include <boost/hana/core/to.hpp> #include <boost/hana/core/dispatch.hpp> #include <boost/hana/detail/has_common_embedding.hpp> #include <boost/hana/detail/nested_than.hpp> // required by fwd decl #include <boost/hana/less.hpp> #include <boost/hana/not.hpp> #include <type_traits> BOOST_HANA_NAMESPACE_BEGIN //! @cond template <typename X, typename Y> constexpr auto less_equal_t::operator()(X&& x, Y&& y) const { using T = typename hana::tag_of<X>::type; using U = typename hana::tag_of<Y>::type; using LessEqual = BOOST_HANA_DISPATCH_IF( decltype(less_equal_impl<T, U>{}), hana::Orderable<T>::value && hana::Orderable<U>::value ); #ifndef BOOST_HANA_CONFIG_DISABLE_CONCEPT_CHECKS static_assert(hana::Orderable<T>::value, "hana::less_equal(x, y) requires 'x' to be Orderable"); static_assert(hana::Orderable<U>::value, "hana::less_equal(x, y) requires 'y' to be Orderable"); #endif return LessEqual::apply(static_cast<X&&>(x), static_cast<Y&&>(y)); } //! @endcond template <typename T, typename U, bool condition> struct less_equal_impl<T, U, when<condition>> : default_ { template <typename X, typename Y> static constexpr decltype(auto) apply(X&& x, Y&& y) { return hana::not_(hana::less(static_cast<Y&&>(y), static_cast<X&&>(x))); } }; // Cross-type overload template <typename T, typename U> struct less_equal_impl<T, U, when< detail::has_nontrivial_common_embedding<Orderable, T, U>::value >> { using C = typename hana::common<T, U>::type; template <typename X, typename Y> static constexpr decltype(auto) apply(X&& x, Y&& y) { return hana::less_equal(hana::to<C>(static_cast<X&&>(x)), hana::to<C>(static_cast<Y&&>(y))); } }; BOOST_HANA_NAMESPACE_END #endif // !BOOST_HANA_LESS_EQUAL_HPP