ceph/src/boost/libs/hana/example/core/convert/embedding.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/assert.hpp>
   6 #include <boost/hana/core/to.hpp>
   7 #include <boost/hana/core/when.hpp>
   8
   9 #include <vector>
  10 namespace hana = boost::hana;
  11
  12
  13 namespace boost { namespace hana {
  14     template <typename To, typename From>
  15     struct to_impl<std::vector<To>, std::vector<From>,
  16         when<is_convertible<From, To>::value>>
  17         : embedding<is_embedded<From, To>::value>
  18     {
  19         static std::vector<To> apply(std::vector<From> const& xs) {
  20             std::vector<To> result;
  21             for (auto const& x: xs)
  22                 result.push_back(to<To>(x));
  23             return result;
  24         }
  25     };
  26 }}
  27
  28 int main() {
  29     BOOST_HANA_RUNTIME_CHECK(
  30         hana::to<std::vector<int>>(std::vector<float>{1.1, 2.2, 3.3})
  31                         ==
  32         std::vector<int>{1, 2, 3}
  33     );
  34
  35     static_assert(!hana::is_embedded<std::vector<float>, std::vector<int>>{}, "");
  36 }