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- /*!
- @file
- Forward declares `boost::hana::zip_with`.
- @copyright Louis Dionne 2013-2017
- Distributed under the Boost Software License, Version 1.0.
- (See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt)
- */
- #ifndef BOOST_HANA_FWD_ZIP_WITH_HPP
- #define BOOST_HANA_FWD_ZIP_WITH_HPP
- #include <boost/hana/config.hpp>
- #include <boost/hana/core/when.hpp>
- BOOST_HANA_NAMESPACE_BEGIN
- //! Zip one sequence or more with a given function.
- //! @ingroup group-Sequence
- //!
- //! Given a `n`-ary function `f` and `n` sequences `s1, ..., sn`,
- //! `zip_with` produces a sequence whose `i`-th element is
- //! `f(s1[i], ..., sn[i])`, where `sk[i]` denotes the `i`-th element of
- //! the `k`-th sequence. In other words, `zip_with` produces a sequence
- //! of the form
- //! @code
- //! [
- //! f(s1[0], ..., sn[0]),
- //! f(s1[1], ..., sn[1]),
- //! ...
- //! f(s1[M], ..., sn[M])
- //! ]
- //! @endcode
- //! where `M` is the length of the sequences, which are all assumed to
- //! have the same length. Assuming the sequences to all have the same size
- //! allows the library to perform some optimizations. To zip sequences
- //! that may have different lengths, `zip_shortest_with` should be used
- //! instead. Also note that it is an error to provide no sequence at all,
- //! i.e. `zip_with` expects at least one sequence.
- //!
- //!
- //! Example
- //! -------
- //! @include example/zip_with.cpp
- #ifdef BOOST_HANA_DOXYGEN_INVOKED
- constexpr auto zip_with = [](auto&& f, auto&& x1, ..., auto&& xn) {
- return tag-dispatched;
- };
- #else
- template <typename S, typename = void>
- struct zip_with_impl : zip_with_impl<S, when<true>> { };
- struct zip_with_t {
- template <typename F, typename Xs, typename ...Ys>
- constexpr auto operator()(F&& f, Xs&& xs, Ys&& ...ys) const;
- };
- constexpr zip_with_t zip_with{};
- #endif
- BOOST_HANA_NAMESPACE_END
- #endif // !BOOST_HANA_FWD_ZIP_WITH_HPP
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