64 lines
1.9 KiB
C++
64 lines
1.9 KiB
C++
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/*!
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@file
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Forward declares `boost::hana::replace_if`.
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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_IF_HPP
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#define BOOST_HANA_FWD_REPLACE_IF_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 satisfying a `predicate`
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//! with a 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 `Bool` a Logical, the signature is
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//! \f$
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//! \mathtt{replace_if} : F(T) \times (T \to Bool) \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 predicate
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//! A function called as `predicate(x)` for element(s) `x` of the
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//! structure and returning a `Logical` representing whether `x`
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//! should be replaced by `value`.
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//!
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//! @param value
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//! A value by which every element `x` of the structure for which
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//! `predicate` returns a true-valued `Logical` 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_if.cpp
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#ifdef BOOST_HANA_DOXYGEN_INVOKED
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constexpr auto replace_if = [](auto&& xs, auto&& predicate, auto&& value) {
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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_if_impl : replace_if_impl<Xs, when<true>> { };
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struct replace_if_t {
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template <typename Xs, typename Pred, typename Value>
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constexpr auto operator()(Xs&& xs, Pred&& pred, Value&& value) const;
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};
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constexpr replace_if_t replace_if{};
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#endif
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BOOST_HANA_NAMESPACE_END
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#endif // !BOOST_HANA_FWD_REPLACE_IF_HPP
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