1/*!
2@file
3Defines `boost::hana::fill`.
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_FILL_HPP
11#define BOOST_HANA_FILL_HPP
12
13#include <boost/hana/fwd/fill.hpp>
14
15#include <boost/hana/concept/functor.hpp>
16#include <boost/hana/concept/sequence.hpp>
17#include <boost/hana/config.hpp>
18#include <boost/hana/core/dispatch.hpp>
19#include <boost/hana/core/make.hpp>
20#include <boost/hana/functional/always.hpp>
21#include <boost/hana/transform.hpp>
22#include <boost/hana/unpack.hpp>
23
24
25namespace boost { namespace hana {
26 //! @cond
27 template <typename Xs, typename Value>
28 constexpr auto fill_t::operator()(Xs&& xs, Value&& value) const {
29 using S = typename hana::tag_of<Xs>::type;
30 using Fill = BOOST_HANA_DISPATCH_IF(fill_impl<S>,
31 hana::Functor<S>::value
32 );
33
34 #ifndef BOOST_HANA_CONFIG_DISABLE_CONCEPT_CHECKS
35 static_assert(hana::Functor<S>::value,
36 "hana::fill(xs, value) requires 'xs' to be a Functor");
37 #endif
38
39 return Fill::apply(static_cast<Xs&&>(xs),
40 static_cast<Value&&>(value));
41 }
42 //! @endcond
43
44 template <typename Fun, bool condition>
45 struct fill_impl<Fun, when<condition>> : default_ {
46 template <typename Xs, typename Value>
47 static constexpr auto apply(Xs&& xs, Value&& v) {
48 return hana::transform(static_cast<Xs&&>(xs),
49 hana::always(static_cast<Value&&>(v))
50 );
51 }
52 };
53
54 template <typename S>
55 struct fill_impl<S, when<Sequence<S>::value>> {
56 //! @cond
57 template <typename V>
58 struct filler {
59 V const& v;
60 template <typename ...Xs>
61 constexpr auto operator()(Xs const& ...xs) const {
62 return hana::make<S>(((void)xs, v)...);
63 }
64 };
65 //! @endcond
66
67 template <typename Xs, typename V>
68 static constexpr auto apply(Xs const& xs, V const& v) {
69 return hana::unpack(xs, filler<V>{v});
70 }
71 };
72}} // end namespace boost::hana
73
74#endif // !BOOST_HANA_FILL_HPP
75

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