/*! @file Defines `boost::hana::remove`. @copyright Louis Dionne 2013-2017 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_REMOVE_HPP #define BOOST_HANA_REMOVE_HPP #include <boost/hana/fwd/remove.hpp> #include <boost/hana/concept/monad_plus.hpp> #include <boost/hana/config.hpp> #include <boost/hana/core/dispatch.hpp> #include <boost/hana/equal.hpp> #include <boost/hana/filter.hpp> #include <boost/hana/functional/compose.hpp> #include <boost/hana/not.hpp> namespace boost { namespace hana { //! @cond template <typename Xs, typename Value> constexpr auto remove_t::operator()(Xs&& xs, Value&& value) const { using M = typename hana::tag_of<Xs>::type; using Remove = BOOST_HANA_DISPATCH_IF(remove_impl<M>, hana::MonadPlus<M>::value ); #ifndef BOOST_HANA_CONFIG_DISABLE_CONCEPT_CHECKS static_assert(hana::MonadPlus<M>::value, "hana::remove(xs, value) requires 'xs' to be a MonadPlus"); #endif return Remove::apply(static_cast<Xs&&>(xs), static_cast<Value&&>(value)); } //! @endcond template <typename M, bool condition> struct remove_impl<M, when<condition>> : default_ { template <typename Xs, typename Value> static constexpr auto apply(Xs&& xs, Value&& value) { return hana::filter(static_cast<Xs&&>(xs), hana::compose(hana::not_, hana::equal.to(static_cast<Value&&>(value)))); } }; }} // end namespace boost::hana #endif // !BOOST_HANA_REMOVE_HPP