1 /*! 2 @file 3 Forward declares `boost::hana::transform`. 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_TRANSFORM_HPP 11 #define BOOST_HANA_FWD_TRANSFORM_HPP 12 13 #include <boost/hana/config.hpp> 14 #include <boost/hana/core/when.hpp> 15 16 17 BOOST_HANA_NAMESPACE_BEGIN 18 //! Map a function over a `Functor`. 19 //! @ingroup group-Functor 20 //! 21 //! 22 //! Signature 23 //! --------- 24 //! Given `F` a Functor, the signature is 25 //! \f$ 26 //! \mathtt{transform} : F(T) \times (T \to U) \to F(U) 27 //! \f$ 28 //! 29 //! @param xs 30 //! The structure to map `f` over. 31 //! 32 //! @param f 33 //! A function called as `f(x)` on element(s) `x` of the structure, 34 //! and returning a new value to replace `x` in the structure. 35 //! 36 //! 37 //! Example 38 //! ------- 39 //! @include example/transform.cpp 40 #ifdef BOOST_HANA_DOXYGEN_INVOKED __anond0a9b2210102(auto&& xs, auto&& f) 41 constexpr auto transform = [](auto&& xs, auto&& f) { 42 return tag-dispatched; 43 }; 44 #else 45 template <typename Xs, typename = void> 46 struct transform_impl : transform_impl<Xs, when<true>> { }; 47 48 struct transform_t { 49 template <typename Xs, typename F> 50 constexpr auto operator()(Xs&& xs, F&& f) const; 51 }; 52 53 constexpr transform_t transform{}; 54 #endif 55 BOOST_HANA_NAMESPACE_END 56 57 #endif // !BOOST_HANA_FWD_TRANSFORM_HPP 58