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- /*!
- @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>
- BOOST_HANA_NAMESPACE_BEGIN
- //! @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))));
- }
- };
- BOOST_HANA_NAMESPACE_END
- #endif // !BOOST_HANA_REMOVE_HPP
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