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43 lines
1.3 KiB
C++
43 lines
1.3 KiB
C++
/*
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@copyright Louis Dionne 2014
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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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*/
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#include <boost/hana/assert.hpp>
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#include <boost/hana/detail/constexpr.hpp>
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#include <boost/hana/ext/std/integral_constant.hpp>
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#include <boost/hana/functional.hpp>
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#include <boost/hana/type.hpp>
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#include <type_traits>
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using namespace boost::hana;
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int main() {
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//! [heterogeneous]
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BOOST_HANA_CONSTEXPR_LAMBDA auto safe_make_unsigned = [](auto t) {
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return eval_if(trait<std::is_integral>(t),
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[=](auto id) { return id(template_<std::make_unsigned_t>)(t); },
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always(t)
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);
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};
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BOOST_HANA_CONSTANT_CHECK(safe_make_unsigned(type<void>) == type<void>);
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BOOST_HANA_CONSTANT_CHECK(safe_make_unsigned(type<int>) == type<unsigned int>);
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//! [heterogeneous]
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(void)safe_make_unsigned;
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//! [homogeneous]
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BOOST_HANA_CONSTEXPR_LAMBDA auto safe_divide = [](auto x, auto y) {
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return eval_if(y == 0,
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[=](auto) { return 0; },
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[=](auto id) { return id(x) / y; }
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);
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};
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BOOST_HANA_CONSTEXPR_CHECK(safe_divide(6, 3) == 2);
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BOOST_HANA_CONSTEXPR_CHECK(safe_divide(6, 0) == 0);
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//! [homogeneous]
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}
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