62 lines
1.9 KiB
C++
62 lines
1.9 KiB
C++
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/*!
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@file
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Forward declares `boost::hana::zip`.
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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_ZIP_HPP
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#define BOOST_HANA_FWD_ZIP_HPP
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#include <boost/hana/config.hpp>
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#include <boost/hana/core/when.hpp>
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BOOST_HANA_NAMESPACE_BEGIN
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//! Zip one sequence or more.
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//! @ingroup group-Sequence
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//!
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//! Given `n` sequences `s1, ..., sn`, `zip` produces a sequence whose
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//! `i`-th element is a tuple of `(s1[i], ..., sn[i])`, where `sk[i]`
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//! denotes the `i`-th element of the `k`-th sequence. In other words,
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//! `zip` produces a sequence of the form
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//! @code
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//! [
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//! make_tuple(s1[0], ..., sn[0]),
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//! make_tuple(s1[1], ..., sn[1]),
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//! ...
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//! make_tuple(s1[M], ..., sn[M])
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//! ]
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//! @endcode
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//! where `M` is the length of the sequences, which are all assumed to
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//! have the same length. Assuming the sequences to all have the same size
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//! allows the library to perform some optimizations. To zip sequences
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//! that may have different lengths, `zip_shortest` should be used
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//! instead. Also note that it is an error to provide no sequence at all,
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//! i.e. `zip` expects at least one sequence.
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//!
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//!
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//! Example
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//! -------
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//! @include example/zip.cpp
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#ifdef BOOST_HANA_DOXYGEN_INVOKED
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constexpr auto zip = [](auto&& x1, ..., auto&& xn) {
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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 zip_impl : zip_impl<S, when<true>> { };
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struct zip_t {
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template <typename Xs, typename ...Ys>
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constexpr auto operator()(Xs&& xs, Ys&& ...ys) const;
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};
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constexpr zip_t zip{};
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#endif
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BOOST_HANA_NAMESPACE_END
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#endif // !BOOST_HANA_FWD_ZIP_HPP
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