| 1 | // Copyright Louis Dionne 2013-2022 |
|---|---|
| 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> |
| 26 | 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> |
| 34 | 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>> { |
| 39 | static constexpr auto apply(counter<i>) { return hana::false_c; } |
| 40 | }; |
| 41 | }} |
| 42 | |
| 43 | |
| 44 | int 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 |