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1 | /*! |
2 | @file | |
3 | Defines `boost::hana::insert_range`. | |
4 | ||
5 | @copyright Louis Dionne 2013-2016 | |
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_INSERT_RANGE_HPP | |
11 | #define BOOST_HANA_INSERT_RANGE_HPP | |
12 | ||
13 | #include <boost/hana/fwd/insert_range.hpp> | |
14 | ||
15 | #include <boost/hana/concat.hpp> | |
16 | #include <boost/hana/concept/foldable.hpp> | |
17 | #include <boost/hana/concept/sequence.hpp> | |
18 | #include <boost/hana/config.hpp> | |
19 | #include <boost/hana/core/to.hpp> | |
20 | #include <boost/hana/core/dispatch.hpp> | |
21 | #include <boost/hana/drop_front.hpp> | |
22 | #include <boost/hana/take_front.hpp> | |
23 | ||
24 | ||
25 | BOOST_HANA_NAMESPACE_BEGIN | |
26 | //! @cond | |
27 | template <typename Xs, typename N, typename Elements> | |
28 | constexpr auto insert_range_t::operator()(Xs&& xs, N&& n, Elements&& elements) const { | |
29 | using S = typename hana::tag_of<Xs>::type; | |
30 | using InsertRange = BOOST_HANA_DISPATCH_IF(insert_range_impl<S>, | |
31 | hana::Sequence<Xs>::value && | |
32 | hana::Foldable<Elements>::value | |
33 | ); | |
34 | ||
35 | #ifndef BOOST_HANA_CONFIG_DISABLE_CONCEPT_CHECKS | |
36 | static_assert(hana::Sequence<Xs>::value, | |
37 | "hana::insert_range(xs, n, elements) requires 'xs' to be a Sequence"); | |
38 | ||
39 | static_assert(hana::Foldable<Elements>::value, | |
40 | "hana::insert_range(xs, n, elements) requires 'elements' to be a Foldable"); | |
41 | #endif | |
42 | ||
43 | return InsertRange::apply(static_cast<Xs&&>(xs), | |
44 | static_cast<N&&>(n), | |
45 | static_cast<Elements&&>(elements)); | |
46 | } | |
47 | //! @endcond | |
48 | ||
49 | template <typename S, bool condition> | |
50 | struct insert_range_impl<S, when<condition>> { | |
51 | template <typename Xs, typename N, typename Elements> | |
52 | static constexpr auto apply(Xs&& xs, N const& n, Elements&& e) { | |
53 | return hana::concat( | |
54 | hana::concat( | |
55 | hana::take_front(xs, n), | |
56 | hana::to<S>(static_cast<Elements&&>(e)) | |
57 | ), | |
58 | hana::drop_front(xs, n) | |
59 | ); | |
60 | } | |
61 | }; | |
62 | BOOST_HANA_NAMESPACE_END | |
63 | ||
64 | #endif // !BOOST_HANA_INSERT_RANGE_HPP |