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- /*!
- @file
- Forward declares `boost::hana::intersection`.
- @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_FWD_INTERSECTION_HPP
- #define BOOST_HANA_FWD_INTERSECTION_HPP
- #include <boost/hana/config.hpp>
- #include <boost/hana/core/when.hpp>
- BOOST_HANA_NAMESPACE_BEGIN
- //! Returns the intersection of two sets.
- //! @relates hana::set
- //!
- //! Given two sets `xs` and `ys`, `intersection(xs, ys)` is a new set
- //! containing exactly those elements that are present both in `xs` and
- //! in `ys`. In other words, the following holds for any object `x`:
- //! @code
- //! x ^in^ intersection(xs, ys) if and only if x ^in^ xs && x ^in^ ys
- //! @endcode
- //!
- //!
- //! @param xs, ys
- //! Two sets to intersect.
- //!
- //!
- //! Example
- //! -------
- //! @include example/intersection.cpp
- //!
- //!
- //! Benchmarks
- //! ----------
- //! <div class="benchmark-chart"
- //! style="min-width: 310px; height: 400px; margin: 0 auto"
- //! data-dataset="benchmark.intersection.compile.json">
- //! </div>
- #ifdef BOOST_HANA_DOXYGEN_INVOKED
- constexpr auto intersection = [](auto&& xs, auto&& ys) {
- return tag-dispatched;
- };
- #else
- template <typename S, typename = void>
- struct intersection_impl : intersection_impl<S, when<true>> { };
- struct intersection_t {
- template <typename Xs, typename Ys>
- constexpr auto operator()(Xs&& xs, Ys&& ys) const;
- };
- constexpr intersection_t intersection{};
- #endif
- BOOST_HANA_NAMESPACE_END
- #endif // !BOOST_HANA_FWD_INTERSECTION_HPP
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