ceph/src/boost/libs/hana/include/boost/hana/fwd/zip_with.hpp

   1 /*!
   2 @file
   3 Forward declares `boost::hana::zip_with`.
   4
   5 @copyright Louis Dionne 2013-2016
   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_FWD_ZIP_WITH_HPP
  11 #define BOOST_HANA_FWD_ZIP_WITH_HPP
  12
  13 #include <boost/hana/config.hpp>
  14 #include <boost/hana/core/when.hpp>
  15
  16
  17 BOOST_HANA_NAMESPACE_BEGIN
  18     //! Zip one sequence or more with a given function.
  19     //! @ingroup group-Sequence
  20     //!
  21     //! Given a `n`-ary function `f` and `n` sequences `s1, ..., sn`,
  22     //! `zip_with` produces a sequence whose `i`-th element is
  23     //! `f(s1[i], ..., sn[i])`, where `sk[i]` denotes the `i`-th element of
  24     //! the `k`-th sequence. In other words, `zip_with` produces a sequence
  25     //! of the form
  26     //! @code
  27     //!     [
  28     //!         f(s1[0], ..., sn[0]),
  29     //!         f(s1[1], ..., sn[1]),
  30     //!         ...
  31     //!         f(s1[M], ..., sn[M])
  32     //!     ]
  33     //! @endcode
  34     //! where `M` is the length of the sequences, which are all assumed to
  35     //! have the same length. Assuming the sequences to all have the same size
  36     //! allows the library to perform some optimizations. To zip sequences
  37     //! that may have different lengths, `zip_shortest_with` should be used
  38     //! instead. Also note that it is an error to provide no sequence at all,
  39     //! i.e. `zip_with` expects at least one sequence.
  40     //!
  41     //!
  42     //! Example
  43     //! -------
  44     //! @include example/zip_with.cpp
  45 #ifdef BOOST_HANA_DOXYGEN_INVOKED
  46     constexpr auto zip_with = [](auto&& f, auto&& x1, ..., auto&& xn) {
  47         return tag-dispatched;
  48     };
  49 #else
  50     template <typename S, typename = void>
  51     struct zip_with_impl : zip_with_impl<S, when<true>> { };
  52
  53     struct zip_with_t {
  54         template <typename F, typename Xs, typename ...Ys>
  55         constexpr auto operator()(F&& f, Xs&& xs, Ys&& ...ys) const;
  56     };
  57
  58     constexpr zip_with_t zip_with{};
  59 #endif
  60 BOOST_HANA_NAMESPACE_END
  61
  62 #endif // !BOOST_HANA_FWD_ZIP_WITH_HPP