boost/hana/contains.hpp

0001 /*!
0002 @file
0003 Defines `boost::hana::contains` and `boost::hana::in`.
0004
0005 Copyright Louis Dionne 2013-2022
0006 Distributed under the Boost Software License, Version 1.0.
0007 (See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt)
0008  */
0009
0010 #ifndef BOOST_HANA_CONTAINS_HPP
0011 #define BOOST_HANA_CONTAINS_HPP
0012
0013 #include <boost/hana/fwd/contains.hpp>
0014
0015 #include <boost/hana/any_of.hpp>
0016 #include <boost/hana/concept/searchable.hpp>
0017 #include <boost/hana/config.hpp>
0018 #include <boost/hana/core/dispatch.hpp>
0019 #include <boost/hana/equal.hpp>
0020
0021
0022 namespace boost { namespace hana {
0023     //! @cond
0024     template <typename Xs, typename Key>
0025     constexpr auto contains_t::operator()(Xs&& xs, Key&& key) const {
0026         using S = typename hana::tag_of<Xs>::type;
0027         using Contains = BOOST_HANA_DISPATCH_IF(contains_impl<S>,
0028             hana::Searchable<S>::value
0029         );
0030
0031     #ifndef BOOST_HANA_CONFIG_DISABLE_CONCEPT_CHECKS
0032         static_assert(hana::Searchable<S>::value,
0033         "hana::contains(xs, key) requires 'xs' to be a Searchable");
0034     #endif
0035
0036         return Contains::apply(static_cast<Xs&&>(xs),
0037                                static_cast<Key&&>(key));
0038     }
0039     //! @endcond
0040
0041     template <typename S, bool condition>
0042     struct contains_impl<S, when<condition>> : default_ {
0043         template <typename Xs, typename X>
0044         static constexpr auto apply(Xs&& xs, X&& x) {
0045             return hana::any_of(static_cast<Xs&&>(xs),
0046                     hana::equal.to(static_cast<X&&>(x)));
0047         }
0048     };
0049 }} // end namespace boost::hana
0050
0051 #endif // !BOOST_HANA_CONTAINS_HPP