1 /*! 2 @file 3 Forward declares `boost::hana::adjust_if`. 4 5 @copyright Louis Dionne 2013-2017 6 Distributed under the Boost Software License, Version 1.0. 7 (See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt) 8 */ 9 10 #ifndef BOOST_HANA_FWD_ADJUST_IF_HPP 11 #define BOOST_HANA_FWD_ADJUST_IF_HPP 12 13 #include <boost/hana/config.hpp> 14 #include <boost/hana/core/when.hpp> 15 16 17 BOOST_HANA_NAMESPACE_BEGIN 18 //! Apply a function on all the elements of a structure satisfying a predicate. 19 //! @ingroup group-Functor 20 //! 21 //! Given a Functor, a predicate `pred` and a function `f`, `adjust_if` 22 //! will _adjust_ the elements of the Functor that satisfy the predicate 23 //! with the function `f`. In other words, `adjust_if` will return a new 24 //! Functor equal to the original one, except that the elements satisfying 25 //! the predicate will be transformed with the given function. Elements 26 //! for which the predicate is not satisfied are left untouched, and they 27 //! are kept as-is in the resulting Functor. 28 //! 29 //! 30 //! Signature 31 //! --------- 32 //! Given a `Functor` `F` and a `Logical` `Bool`, the signature is 33 //! \f$ 34 //! \mathtt{adjust\_if} : F(T) \times (T \to Bool) \times (T \to T) \to F(T) 35 //! \f$ 36 //! 37 //! @param xs 38 //! The structure to adjust with `f`. 39 //! 40 //! @param pred 41 //! A function called as `pred(x)` for each element of the Functor, 42 //! and returning whether `f` should be applied on that element. 43 //! 44 //! @param f 45 //! A function called as `f(x)` on the element(s) of the Functor that 46 //! satisfy the predicate. 47 //! 48 //! 49 //! Example 50 //! ------- 51 //! @include example/adjust_if.cpp 52 #ifdef BOOST_HANA_DOXYGEN_INVOKED __anon0b73356b0102(auto&& xs, auto const& pred, auto const& f) 53 constexpr auto adjust_if = [](auto&& xs, auto const& pred, auto const& f) { 54 return tag-dispatched; 55 }; 56 #else 57 template <typename Xs, typename = void> 58 struct adjust_if_impl : adjust_if_impl<Xs, when<true>> { }; 59 60 struct adjust_if_t { 61 template <typename Xs, typename Pred, typename F> 62 constexpr auto operator()(Xs&& xs, Pred const& pred, F const& f) const; 63 }; 64 65 constexpr adjust_if_t adjust_if{}; 66 #endif 67 BOOST_HANA_NAMESPACE_END 68 69 #endif // !BOOST_HANA_FWD_ADJUST_IF_HPP 70