ceph/src/boost/libs/hana/example/zip_with.cpp

   1 // Copyright Louis Dionne 2013-2017
   2 // Distributed under the Boost Software License, Version 1.0.
   3 // (See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt)
   4
   5 #include <boost/hana/equal.hpp>
   6 #include <boost/hana/ext/std/tuple.hpp>
   7 #include <boost/hana/mult.hpp>
   8 #include <boost/hana/transform.hpp>
   9 #include <boost/hana/tuple.hpp>
  10 #include <boost/hana/type.hpp>
  11 #include <boost/hana/unpack.hpp>
  12 #include <boost/hana/zip_with.hpp>
  13
  14 #include <tuple>
  15 #include <type_traits>
  16 #include <utility>
  17 namespace hana = boost::hana;
  18
  19
  20 // Basic usage:
  21 static_assert(
  22     hana::zip_with(hana::mult, hana::make_tuple(1, 2, 3, 4), hana::make_tuple(5, 6, 7, 8))
  23     ==
  24     hana::make_tuple(5, 12, 21, 32)
  25 , "");
  26
  27
  28
  29 // Example of computing a tuple of all the common types of several tuples:
  30 template<typename... Ts>
  31 using common_tuple_t = typename decltype(
  32     hana::unpack(
  33         hana::zip_with(
  34             hana::metafunction<std::common_type>,
  35             hana::transform(std::declval<Ts>(), hana::decltype_)...
  36         ),
  37         hana::template_<std::tuple>
  38     )
  39 )::type;
  40
  41
  42 static_assert(std::is_same<
  43     common_tuple_t<
  44         std::tuple<bool, int, unsigned>,
  45         std::tuple<char, long, long>,
  46         std::tuple<int, long long, double>
  47     >,
  48     std::tuple<int, long long, double>
  49 >::value, "");
  50
  51 int main() { }