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