1 /*! 2 @file 3 Defines `boost::hana::insert`. 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_INSERT_HPP 11 #define BOOST_HANA_INSERT_HPP 12 13 #include <boost/hana/fwd/insert.hpp> 14 15 #include <boost/hana/append.hpp> 16 #include <boost/hana/concat.hpp> 17 #include <boost/hana/concept/sequence.hpp> 18 #include <boost/hana/config.hpp> 19 #include <boost/hana/core/dispatch.hpp> 20 #include <boost/hana/drop_front.hpp> 21 #include <boost/hana/take_front.hpp> 22 23 24 BOOST_HANA_NAMESPACE_BEGIN 25 //! @cond 26 template <typename Set, typename ...Args> operator ()(Set && set,Args &&...args) const27 constexpr decltype(auto) insert_t::operator()(Set&& set, Args&& ...args) const { 28 return insert_impl<typename hana::tag_of<Set>::type>::apply( 29 static_cast<Set&&>(set), 30 static_cast<Args&&>(args)... 31 ); 32 } 33 //! @endcond 34 35 template <typename T, bool condition> 36 struct insert_impl<T, when<condition>> : default_ { 37 template <typename ...Args> 38 static constexpr auto apply(Args&& ...) = delete; 39 }; 40 41 template <typename S> 42 struct insert_impl<S, when<Sequence<S>::value>> { 43 template <typename Xs, typename N, typename Element> applyinsert_impl44 static constexpr auto apply(Xs&& xs, N const& n, Element&& e) { 45 return hana::concat(hana::append(hana::take_front(xs, n), 46 static_cast<Element&&>(e)), 47 hana::drop_front(xs, n)); 48 } 49 }; 50 BOOST_HANA_NAMESPACE_END 51 52 #endif // !BOOST_HANA_INSERT_HPP 53