83 lines
2.4 KiB
C++
83 lines
2.4 KiB
C++
/*!
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@file
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Forward declares `boost::hana::remove_at` and `boost::hana::remove_at_c`.
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@copyright Louis Dionne 2013-2016
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Distributed under the Boost Software License, Version 1.0.
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(See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt)
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*/
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#ifndef BOOST_HANA_FWD_REMOVE_AT_HPP
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#define BOOST_HANA_FWD_REMOVE_AT_HPP
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#include <boost/hana/config.hpp>
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#include <boost/hana/core/when.hpp>
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#include <cstddef>
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BOOST_HANA_NAMESPACE_BEGIN
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//! Remove the element at a given index from a sequence.
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//! @ingroup group-Sequence
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//!
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//! `remove_at` returns a new sequence identical to the original, except
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//! that the element at the given index is removed. Specifically,
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//! `remove_at([x0, ..., xn-1, xn, xn+1, ..., xm], n)` is a new
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//! sequence equivalent to `[x0, ..., xn-1, xn+1, ..., xm]`.
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//!
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//! @note
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//! The behavior is undefined if the index is out of the bounds of the
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//! sequence.
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//!
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//!
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//! @param xs
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//! A sequence from which an element is to be removed.
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//!
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//! @param n
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//! An non-negative `IntegralConstant` representing the index of the
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//! element to be removed from the sequence. The behavior is undefined
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//! if that index is not in the bounds of the sequence.
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//!
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//!
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//! Example
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//! -------
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//! @include example/remove_at.cpp
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#ifdef BOOST_HANA_DOXYGEN_INVOKED
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constexpr auto remove_at = [](auto&& xs, auto const& n) {
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return tag-dispatched;
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};
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#else
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template <typename S, typename = void>
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struct remove_at_impl : remove_at_impl<S, when<true>> { };
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struct remove_at_t {
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template <typename Xs, typename N>
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constexpr auto operator()(Xs&& xs, N const& n) const;
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};
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constexpr remove_at_t remove_at{};
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#endif
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//! Equivalent to `remove_at`; provided for convenience.
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//! @ingroup group-Sequence
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//!
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//!
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//! Example
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//! -------
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//! @include example/remove_at_c.cpp
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#ifdef BOOST_HANA_DOXYGEN_INVOKED
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template <std::size_t n>
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constexpr auto remove_at_c = [](auto&& xs) {
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return hana::remove_at(forwarded(xs), hana::size_c<n>);
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};
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#else
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template <std::size_t n>
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struct remove_at_c_t;
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template <std::size_t n>
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constexpr remove_at_c_t<n> remove_at_c{};
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#endif
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BOOST_HANA_NAMESPACE_END
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#endif // !BOOST_HANA_FWD_REMOVE_AT_HPP
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