57 lines
1.8 KiB
C++
57 lines
1.8 KiB
C++
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/*!
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@file
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Defines `boost::hana::replace`.
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@copyright Louis Dionne 2013-2016
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Distributed under the Boost Software License, Version 1.0.
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(See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt)
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*/
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#ifndef BOOST_HANA_REPLACE_HPP
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#define BOOST_HANA_REPLACE_HPP
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#include <boost/hana/fwd/replace.hpp>
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#include <boost/hana/concept/functor.hpp>
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#include <boost/hana/config.hpp>
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#include <boost/hana/core/dispatch.hpp>
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#include <boost/hana/equal.hpp>
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#include <boost/hana/replace_if.hpp>
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BOOST_HANA_NAMESPACE_BEGIN
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//! @cond
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template <typename Xs, typename OldVal, typename NewVal>
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constexpr auto replace_t::operator()(Xs&& xs, OldVal&& oldval, NewVal&& newval) const {
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using S = typename hana::tag_of<Xs>::type;
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using Replace = BOOST_HANA_DISPATCH_IF(replace_impl<S>,
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hana::Functor<S>::value
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);
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#ifndef BOOST_HANA_CONFIG_DISABLE_CONCEPT_CHECKS
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static_assert(hana::Functor<S>::value,
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"hana::replace(xs, oldval, newval) requires 'xs' to be a Functor");
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#endif
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return Replace::apply(static_cast<Xs&&>(xs),
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static_cast<OldVal&&>(oldval),
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static_cast<NewVal&&>(newval));
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}
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//! @endcond
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template <typename Fun, bool condition>
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struct replace_impl<Fun, when<condition>> : default_ {
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template <typename Xs, typename OldVal, typename NewVal>
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static constexpr decltype(auto)
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apply(Xs&& xs, OldVal&& oldval, NewVal&& newval) {
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return hana::replace_if(
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static_cast<Xs&&>(xs),
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hana::equal.to(static_cast<OldVal&&>(oldval)),
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static_cast<NewVal&&>(newval)
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);
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}
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};
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BOOST_HANA_NAMESPACE_END
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#endif // !BOOST_HANA_REPLACE_HPP
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