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/any_of.hpp> 6 #include <boost/hana/assert.hpp> 7 #include <boost/hana/bool.hpp> 8 #include <boost/hana/equal.hpp> 9 #include <boost/hana/find_if.hpp> 10 #include <boost/hana/fwd/at.hpp> 11 #include <boost/hana/fwd/drop_front.hpp> 12 #include <boost/hana/fwd/is_empty.hpp> 13 #include <boost/hana/integral_constant.hpp> 14 #include <boost/hana/optional.hpp> 15 namespace hana = boost::hana; 16 17 18 // A simple infinite Iterable. 19 template <int i> 20 struct counter { }; 21 22 namespace boost { namespace hana { 23 template <int i> 24 struct at_impl<counter<i>> { 25 template <typename N> applyboost::hana::at_impl26 static constexpr auto apply(counter<i>, N const&) { 27 return hana::int_c<i + N::value>; 28 } 29 }; 30 31 template <int i> 32 struct drop_front_impl<counter<i>> { 33 template <typename N> applyboost::hana::drop_front_impl34 static constexpr auto apply(counter<i>, N) { return counter<i + N::value>{}; } 35 }; 36 37 template <int i> 38 struct is_empty_impl<counter<i>> { applyboost::hana::is_empty_impl39 static constexpr auto apply(counter<i>) { return hana::false_c; } 40 }; 41 }} 42 43 main()44int main() { 45 // find_if and any_of should short-circuit and stop even though the 46 // Iterable is infinite. 47 BOOST_HANA_CONSTANT_CHECK(hana::any_of(counter<1>{}, hana::equal.to(hana::int_c<4>))); 48 49 BOOST_HANA_CONSTANT_CHECK(hana::equal( 50 hana::find_if(counter<1>{}, hana::equal.to(hana::int_c<4>)), 51 hana::just(hana::int_c<4>) 52 )); 53 } 54