1234567891011121314151617181920212223242526272829303132333435363738394041424344454647484950 |
- /*!
- @file
- Defines `boost::hana::count`.
- @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_COUNT_HPP
- #define BOOST_HANA_COUNT_HPP
- #include <boost/hana/fwd/count.hpp>
- #include <boost/hana/concept/foldable.hpp>
- #include <boost/hana/config.hpp>
- #include <boost/hana/core/dispatch.hpp>
- #include <boost/hana/count_if.hpp>
- #include <boost/hana/equal.hpp>
- BOOST_HANA_NAMESPACE_BEGIN
- //! @cond
- template <typename Xs, typename Value>
- constexpr auto count_t::operator()(Xs&& xs, Value&& value) const {
- using S = typename hana::tag_of<Xs>::type;
- using Count = BOOST_HANA_DISPATCH_IF(count_impl<S>,
- hana::Foldable<S>::value
- );
- #ifndef BOOST_HANA_CONFIG_DISABLE_CONCEPT_CHECKS
- static_assert(hana::Foldable<S>::value,
- "hana::count(xs, value) requires 'xs' to be Foldable");
- #endif
- return Count::apply(static_cast<Xs&&>(xs), static_cast<Value&&>(value));
- }
- //! @endcond
- template <typename T, bool condition>
- struct count_impl<T, when<condition>> : default_ {
- template <typename Xs, typename Value>
- static constexpr auto apply(Xs&& xs, Value&& value) {
- return hana::count_if(static_cast<Xs&&>(xs),
- hana::equal.to(static_cast<Value&&>(value)));
- }
- };
- BOOST_HANA_NAMESPACE_END
- #endif // !BOOST_HANA_COUNT_HPP
|