boost/hana/insert_range.hpp

0001 /*!
0002 @file
0003 Defines `boost::hana::insert_range`.
0004
0005 Copyright Louis Dionne 2013-2022
0006 Distributed under the Boost Software License, Version 1.0.
0007 (See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt)
0008  */
0009
0010 #ifndef BOOST_HANA_INSERT_RANGE_HPP
0011 #define BOOST_HANA_INSERT_RANGE_HPP
0012
0013 #include <boost/hana/fwd/insert_range.hpp>
0014
0015 #include <boost/hana/concat.hpp>
0016 #include <boost/hana/concept/foldable.hpp>
0017 #include <boost/hana/concept/sequence.hpp>
0018 #include <boost/hana/config.hpp>
0019 #include <boost/hana/core/to.hpp>
0020 #include <boost/hana/core/dispatch.hpp>
0021 #include <boost/hana/drop_front.hpp>
0022 #include <boost/hana/take_front.hpp>
0023
0024
0025 namespace boost { namespace hana {
0026     //! @cond
0027     template <typename Xs, typename N, typename Elements>
0028     constexpr auto insert_range_t::operator()(Xs&& xs, N&& n, Elements&& elements) const {
0029         using S = typename hana::tag_of<Xs>::type;
0030         using InsertRange = BOOST_HANA_DISPATCH_IF(insert_range_impl<S>,
0031             hana::Sequence<Xs>::value &&
0032             hana::Foldable<Elements>::value
0033         );
0034
0035     #ifndef BOOST_HANA_CONFIG_DISABLE_CONCEPT_CHECKS
0036         static_assert(hana::Sequence<Xs>::value,
0037         "hana::insert_range(xs, n, elements) requires 'xs' to be a Sequence");
0038
0039         static_assert(hana::Foldable<Elements>::value,
0040         "hana::insert_range(xs, n, elements) requires 'elements' to be a Foldable");
0041     #endif
0042
0043         return InsertRange::apply(static_cast<Xs&&>(xs),
0044                                   static_cast<N&&>(n),
0045                                   static_cast<Elements&&>(elements));
0046     }
0047     //! @endcond
0048
0049     template <typename S, bool condition>
0050     struct insert_range_impl<S, when<condition>> {
0051         template <typename Xs, typename N, typename Elements>
0052         static constexpr auto apply(Xs&& xs, N const& n, Elements&& e) {
0053             return hana::concat(
0054                     hana::concat(
0055                         hana::take_front(xs, n),
0056                         hana::to<S>(static_cast<Elements&&>(e))
0057                     ),
0058                     hana::drop_front(xs, n)
0059                 );
0060         }
0061     };
0062 }} // end namespace boost::hana
0063
0064 #endif // !BOOST_HANA_INSERT_RANGE_HPP