1/*!
2@file
3Defines `boost::hana::chain`.
4
5Copyright Louis Dionne 2013-2022
6Distributed 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_CHAIN_HPP
11#define BOOST_HANA_CHAIN_HPP
12
13#include <boost/hana/fwd/chain.hpp>
14
15#include <boost/hana/concept/monad.hpp>
16#include <boost/hana/config.hpp>
17#include <boost/hana/core/dispatch.hpp>
18#include <boost/hana/flatten.hpp>
19#include <boost/hana/transform.hpp>
20
21
22namespace boost { namespace hana {
23 //! @cond
24 template <typename Xs, typename F>
25 constexpr decltype(auto) chain_t::operator()(Xs&& xs, F&& f) const {
26 using M = typename hana::tag_of<Xs>::type;
27 using Chain = BOOST_HANA_DISPATCH_IF(chain_impl<M>,
28 hana::Monad<M>::value
29 );
30
31 #ifndef BOOST_HANA_CONFIG_DISABLE_CONCEPT_CHECKS
32 static_assert(hana::Monad<M>::value,
33 "hana::chain(xs, f) requires 'xs' to be a Monad");
34 #endif
35
36 return Chain::apply(static_cast<Xs&&>(xs), static_cast<F&&>(f));
37 }
38 //! @endcond
39
40 template <typename M, bool condition>
41 struct chain_impl<M, when<condition>> : default_ {
42 template <typename Xs, typename F>
43 static constexpr auto apply(Xs&& xs, F&& f) {
44 return hana::flatten(hana::transform(static_cast<Xs&&>(xs),
45 static_cast<F&&>(f)));
46 }
47 };
48}} // end namespace boost::hana
49
50#endif // !BOOST_HANA_CHAIN_HPP
51

source code of boost/libs/hana/include/boost/hana/chain.hpp