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- /*!
- @file
- Defines `boost::hana::fill`.
- Copyright Louis Dionne 2013-2022
- 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_FILL_HPP
- #define BOOST_HANA_FILL_HPP
- #include <boost/hana/fwd/fill.hpp>
- #include <boost/hana/concept/functor.hpp>
- #include <boost/hana/concept/sequence.hpp>
- #include <boost/hana/config.hpp>
- #include <boost/hana/core/dispatch.hpp>
- #include <boost/hana/core/make.hpp>
- #include <boost/hana/functional/always.hpp>
- #include <boost/hana/transform.hpp>
- #include <boost/hana/unpack.hpp>
- namespace boost { namespace hana {
- //! @cond
- template <typename Xs, typename Value>
- constexpr auto fill_t::operator()(Xs&& xs, Value&& value) const {
- using S = typename hana::tag_of<Xs>::type;
- using Fill = BOOST_HANA_DISPATCH_IF(fill_impl<S>,
- hana::Functor<S>::value
- );
- #ifndef BOOST_HANA_CONFIG_DISABLE_CONCEPT_CHECKS
- static_assert(hana::Functor<S>::value,
- "hana::fill(xs, value) requires 'xs' to be a Functor");
- #endif
- return Fill::apply(static_cast<Xs&&>(xs),
- static_cast<Value&&>(value));
- }
- //! @endcond
- template <typename Fun, bool condition>
- struct fill_impl<Fun, when<condition>> : default_ {
- template <typename Xs, typename Value>
- static constexpr auto apply(Xs&& xs, Value&& v) {
- return hana::transform(static_cast<Xs&&>(xs),
- hana::always(static_cast<Value&&>(v))
- );
- }
- };
- template <typename S>
- struct fill_impl<S, when<Sequence<S>::value>> {
- //! @cond
- template <typename V>
- struct filler {
- V const& v;
- template <typename ...Xs>
- constexpr auto operator()(Xs const& ...xs) const {
- return hana::make<S>(((void)xs, v)...);
- }
- };
- //! @endcond
- template <typename Xs, typename V>
- static constexpr auto apply(Xs const& xs, V const& v) {
- return hana::unpack(xs, filler<V>{v});
- }
- };
- }} // end namespace boost::hana
- #endif // !BOOST_HANA_FILL_HPP
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