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- /*!
- @file
- Defines `boost::hana::replace`.
- @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_REPLACE_HPP
- #define BOOST_HANA_REPLACE_HPP
- #include <boost/hana/fwd/replace.hpp>
- #include <boost/hana/concept/functor.hpp>
- #include <boost/hana/config.hpp>
- #include <boost/hana/core/dispatch.hpp>
- #include <boost/hana/equal.hpp>
- #include <boost/hana/replace_if.hpp>
- BOOST_HANA_NAMESPACE_BEGIN
- //! @cond
- template <typename Xs, typename OldVal, typename NewVal>
- constexpr auto replace_t::operator()(Xs&& xs, OldVal&& oldval, NewVal&& newval) const {
- using S = typename hana::tag_of<Xs>::type;
- using Replace = BOOST_HANA_DISPATCH_IF(replace_impl<S>,
- hana::Functor<S>::value
- );
- #ifndef BOOST_HANA_CONFIG_DISABLE_CONCEPT_CHECKS
- static_assert(hana::Functor<S>::value,
- "hana::replace(xs, oldval, newval) requires 'xs' to be a Functor");
- #endif
- return Replace::apply(static_cast<Xs&&>(xs),
- static_cast<OldVal&&>(oldval),
- static_cast<NewVal&&>(newval));
- }
- //! @endcond
- template <typename Fun, bool condition>
- struct replace_impl<Fun, when<condition>> : default_ {
- template <typename Xs, typename OldVal, typename NewVal>
- static constexpr decltype(auto)
- apply(Xs&& xs, OldVal&& oldval, NewVal&& newval) {
- return hana::replace_if(
- static_cast<Xs&&>(xs),
- hana::equal.to(static_cast<OldVal&&>(oldval)),
- static_cast<NewVal&&>(newval)
- );
- }
- };
- BOOST_HANA_NAMESPACE_END
- #endif // !BOOST_HANA_REPLACE_HPP
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