54 lines
1.5 KiB
C++
54 lines
1.5 KiB
C++
// Copyright Louis Dionne 2013-2022
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// Distributed under the Boost Software License, Version 1.0.
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// (See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt)
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#include <boost/hana/any_of.hpp>
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#include <boost/hana/assert.hpp>
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#include <boost/hana/bool.hpp>
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#include <boost/hana/equal.hpp>
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#include <boost/hana/find_if.hpp>
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#include <boost/hana/fwd/at.hpp>
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#include <boost/hana/fwd/drop_front.hpp>
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#include <boost/hana/fwd/is_empty.hpp>
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#include <boost/hana/integral_constant.hpp>
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#include <boost/hana/optional.hpp>
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namespace hana = boost::hana;
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// A simple infinite Iterable.
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template <int i>
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struct counter { };
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namespace boost { namespace hana {
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template <int i>
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struct at_impl<counter<i>> {
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template <typename N>
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static constexpr auto apply(counter<i>, N const&) {
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return hana::int_c<i + N::value>;
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}
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};
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template <int i>
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struct drop_front_impl<counter<i>> {
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template <typename N>
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static constexpr auto apply(counter<i>, N) { return counter<i + N::value>{}; }
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};
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template <int i>
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struct is_empty_impl<counter<i>> {
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static constexpr auto apply(counter<i>) { return hana::false_c; }
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};
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}}
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int main() {
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// find_if and any_of should short-circuit and stop even though the
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// Iterable is infinite.
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BOOST_HANA_CONSTANT_CHECK(hana::any_of(counter<1>{}, hana::equal.to(hana::int_c<4>)));
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BOOST_HANA_CONSTANT_CHECK(hana::equal(
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hana::find_if(counter<1>{}, hana::equal.to(hana::int_c<4>)),
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hana::just(hana::int_c<4>)
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));
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}
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