boost/hana/remove_if.hpp

0001 /*!
0002 @file
0003 Defines `boost::hana::remove_if`.
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_REMOVE_IF_HPP
0011 #define BOOST_HANA_REMOVE_IF_HPP
0012
0013 #include <boost/hana/fwd/remove_if.hpp>
0014
0015 #include <boost/hana/concept/monad_plus.hpp>
0016 #include <boost/hana/config.hpp>
0017 #include <boost/hana/core/dispatch.hpp>
0018 #include <boost/hana/filter.hpp>
0019 #include <boost/hana/functional/compose.hpp>
0020 #include <boost/hana/not.hpp>
0021
0022
0023 namespace boost { namespace hana {
0024     //! @cond
0025     template <typename Xs, typename Pred>
0026     constexpr auto remove_if_t::operator()(Xs&& xs, Pred&& pred) const {
0027         using M = typename hana::tag_of<Xs>::type;
0028         using RemoveIf = BOOST_HANA_DISPATCH_IF(remove_if_impl<M>,
0029             hana::MonadPlus<M>::value
0030         );
0031
0032         #ifndef BOOST_HANA_CONFIG_DISABLE_CONCEPT_CHECKS
0033             static_assert(hana::MonadPlus<M>::value,
0034             "hana::remove_if(xs, predicate) requires 'xs' to be a MonadPlus");
0035         #endif
0036
0037         return RemoveIf::apply(static_cast<Xs&&>(xs),
0038                                static_cast<Pred&&>(pred));
0039     }
0040     //! @endcond
0041
0042     template <typename M, bool condition>
0043     struct remove_if_impl<M, when<condition>> : default_ {
0044         template <typename Xs, typename Pred>
0045         static constexpr auto apply(Xs&& xs, Pred&& pred) {
0046             return hana::filter(static_cast<Xs&&>(xs),
0047                         hana::compose(hana::not_, static_cast<Pred&&>(pred)));
0048         }
0049     };
0050 }} // end namespace boost::hana
0051
0052 #endif // !BOOST_HANA_REMOVE_IF_HPP