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- /*!
- @file
- Forward declares `boost::hana::replace_if`.
- @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_FWD_REPLACE_IF_HPP
- #define BOOST_HANA_FWD_REPLACE_IF_HPP
- #include <boost/hana/config.hpp>
- #include <boost/hana/core/when.hpp>
- BOOST_HANA_NAMESPACE_BEGIN
- //! Replace all the elements of a structure satisfying a `predicate`
- //! with a fixed value.
- //! @ingroup group-Functor
- //!
- //!
- //! Signature
- //! ---------
- //! Given `F` a Functor and `Bool` a Logical, the signature is
- //! \f$
- //! \mathtt{replace\_if} : F(T) \times (T \to Bool) \times T \to F(T)
- //! \f$
- //!
- //! @param xs
- //! The structure to replace elements of.
- //!
- //! @param predicate
- //! A function called as `predicate(x)` for element(s) `x` of the
- //! structure and returning a `Logical` representing whether `x`
- //! should be replaced by `value`.
- //!
- //! @param value
- //! A value by which every element `x` of the structure for which
- //! `predicate` returns a true-valued `Logical` is replaced.
- //!
- //!
- //! Example
- //! -------
- //! @include example/replace_if.cpp
- #ifdef BOOST_HANA_DOXYGEN_INVOKED
- constexpr auto replace_if = [](auto&& xs, auto&& predicate, auto&& value) {
- return tag-dispatched;
- };
- #else
- template <typename Xs, typename = void>
- struct replace_if_impl : replace_if_impl<Xs, when<true>> { };
- struct replace_if_t {
- template <typename Xs, typename Pred, typename Value>
- constexpr auto operator()(Xs&& xs, Pred&& pred, Value&& value) const;
- };
- constexpr replace_if_t replace_if{};
- #endif
- BOOST_HANA_NAMESPACE_END
- #endif // !BOOST_HANA_FWD_REPLACE_IF_HPP
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