ceph/src/boost/libs/hana/example/iterable/searchable.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/ext/std/integral_constant.hpp>
   7 #include <boost/hana/find.hpp>
   8 #include <boost/hana/find_if.hpp>
   9 #include <boost/hana/functional/compose.hpp>
  10 #include <boost/hana/integral_constant.hpp>
  11 #include <boost/hana/optional.hpp>
  12 #include <boost/hana/tuple.hpp>
  13 #include <boost/hana/type.hpp>
  14
  15 #include <type_traits>
  16 namespace hana = boost::hana;
  17
  18
  19 // First get the type of the object, and then call the trait on it.
  20 constexpr auto is_integral = hana::compose(hana::trait<std::is_integral>, hana::typeid_);
  21 constexpr auto is_class = hana::compose(hana::trait<std::is_class>, hana::typeid_);
  22
  23 static_assert(
  24     hana::find_if(hana::make_tuple(1.0, 2, '3'), is_integral)
  25         ==
  26     hana::just(2)
  27 , "");
  28
  29 BOOST_HANA_CONSTANT_CHECK(
  30     hana::find_if(hana::make_tuple(1.0, 2, '3'), is_class)
  31         ==
  32     hana::nothing
  33 );
  34
  35 BOOST_HANA_CONSTANT_CHECK(
  36     hana::find(hana::make_tuple(hana::int_c<1>, hana::char_c<'c'>, hana::type_c<void>), hana::type_c<void>)
  37         ==
  38     hana::just(hana::type_c<void>)
  39 );
  40
  41 BOOST_HANA_CONSTANT_CHECK(
  42     hana::find(hana::make_tuple(hana::int_c<1>, hana::char_c<'c'>, hana::type_c<void>), hana::type_c<int>)
  43         ==
  44     hana::nothing
  45 );
  46
  47 int main() { }