Current File : //proc/309157/task/309157/root/usr/include/boost/hana/fwd/zip_shortest.hpp
/*!
@file
Forward declares `boost::hana::zip_shortest`.
@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_SHORTEST_HPP
#define BOOST_HANA_FWD_ZIP_SHORTEST_HPP
#include <boost/hana/config.hpp>
#include <boost/hana/core/when.hpp>
BOOST_HANA_NAMESPACE_BEGIN
//! Zip one sequence or more.
//! @ingroup group-Sequence
//!
//! Given `n` sequences `s1, ..., sn`, `zip_shortest` produces a sequence
//! whose `i`-th element is a tuple of `(s1[i], ..., sn[i])`, where `sk[i]`
//! denotes the `i`-th element of the `k`-th sequence. In other words,
//! `zip_shortest` produces a sequence of the form
//! @code
//! [
//! make_tuple(s1[0], ..., sn[0]),
//! make_tuple(s1[1], ..., sn[1]),
//! ...
//! make_tuple(s1[M], ..., sn[M])
//! ]
//! @endcode
//! where `M` is the length of the shortest sequence. Hence, the returned
//! sequence stops when the shortest input sequence is exhausted. If you
//! know that all the sequences you are about to zip have the same length,
//! you should use `zip` instead, since it can be more optimized. Also
//! note that it is an error to provide no sequence at all, i.e.
//! `zip_shortest` expects at least one sequence.
//!
//!
//! Example
//! -------
//! @include example/zip_shortest.cpp
#ifdef BOOST_HANA_DOXYGEN_INVOKED
constexpr auto zip_shortest = [](auto&& x1, ..., auto&& xn) {
return tag-dispatched;
};
#else
template <typename S, typename = void>
struct zip_shortest_impl : zip_shortest_impl<S, when<true>> { };
struct zip_shortest_t {
template <typename Xs, typename ...Ys>
constexpr auto operator()(Xs&& xs, Ys&& ...ys) const;
};
constexpr zip_shortest_t zip_shortest{};
#endif
BOOST_HANA_NAMESPACE_END
#endif // !BOOST_HANA_FWD_ZIP_SHORTEST_HPP
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