70 lines
2.3 KiB
C++
70 lines
2.3 KiB
C++
/*!
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@file
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Forward declares `boost::hana::adjust_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_ADJUST_IF_HPP
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#define BOOST_HANA_FWD_ADJUST_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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//! Apply a function on all the elements of a structure satisfying a predicate.
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//! @ingroup group-Functor
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//!
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//! Given a Functor, a predicate `pred` and a function `f`, `adjust_if`
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//! will _adjust_ the elements of the Functor that satisfy the predicate
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//! with the function `f`. In other words, `adjust_if` will return a new
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//! Functor equal to the original one, except that the elements satisfying
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//! the predicate will be transformed with the given function. Elements
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//! for which the predicate is not satisfied are left untouched, and they
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//! are kept as-is in the resulting Functor.
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//!
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//!
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//! Signature
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//! ---------
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//! Given a `Functor` `F` and a `Logical` `Bool`, the signature is
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//! \f$
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//! \mathtt{adjust_if} : F(T) \times (T \to Bool) \times (T \to 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 adjust with `f`.
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//!
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//! @param pred
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//! A function called as `pred(x)` for each element of the Functor,
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//! and returning whether `f` should be applied on that element.
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//!
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//! @param f
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//! A function called as `f(x)` on the element(s) of the Functor that
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//! satisfy the predicate.
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//!
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//!
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//! Example
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//! -------
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//! @include example/adjust_if.cpp
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#ifdef BOOST_HANA_DOXYGEN_INVOKED
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constexpr auto adjust_if = [](auto&& xs, auto const& pred, auto const& f) {
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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 adjust_if_impl : adjust_if_impl<Xs, when<true>> { };
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struct adjust_if_t {
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template <typename Xs, typename Pred, typename F>
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constexpr auto operator()(Xs&& xs, Pred const& pred, F const& f) const;
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};
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constexpr adjust_if_t adjust_if{};
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#endif
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BOOST_HANA_NAMESPACE_END
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#endif // !BOOST_HANA_FWD_ADJUST_IF_HPP
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