65 lines
1.9 KiB
C++
65 lines
1.9 KiB
C++
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/*!
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@file
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Forward declares `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_FWD_REPLACE_HPP
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#define BOOST_HANA_FWD_REPLACE_HPP
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#include <boost/hana/config.hpp>
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#include <boost/hana/core/when.hpp>
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BOOST_HANA_NAMESPACE_BEGIN
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//! Replace all the elements of a structure that compare equal
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//! to some `value` with some new fixed value.
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//! @ingroup group-Functor
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//!
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//!
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//! Signature
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//! ---------
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//! Given `F` a Functor and `U` a type that can be compared with `T`,
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//! the signature is
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//! \f$
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//! \mathtt{replace} : F(T) \times U \times T \to F(T)
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//! \f$
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//!
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//! @param xs
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//! The structure to replace elements of.
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//!
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//! @param oldval
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//! An object compared with each element of the structure. Elements
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//! of the structure that compare equal to `oldval` are replaced
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//! by `newval` in the new structure.
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//!
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//! @param newval
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//! A value by which every element `x` of the structure that compares
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//! equal to `oldval` is replaced.
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//!
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//!
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//! Example
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//! -------
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//! @include example/replace.cpp
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#ifdef BOOST_HANA_DOXYGEN_INVOKED
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constexpr auto replace = [](auto&& xs, auto&& oldval, auto&& newval) {
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return tag-dispatched;
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};
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#else
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template <typename Xs, typename = void>
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struct replace_impl : replace_impl<Xs, when<true>> { };
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struct replace_t {
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template <typename Xs, typename OldVal, typename NewVal>
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constexpr auto operator()(Xs&& xs, OldVal&& oldval, NewVal&& newval) const;
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};
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constexpr replace_t replace{};
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#endif
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BOOST_HANA_NAMESPACE_END
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#endif // !BOOST_HANA_FWD_REPLACE_HPP
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