54 lines
1.6 KiB
C++
54 lines
1.6 KiB
C++
// Copyright Louis Dionne 2013-2017
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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/bool.hpp>
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#include <boost/hana/eval_if.hpp>
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#include <boost/hana/fwd/not.hpp>
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#include <boost/hana/fwd/while.hpp>
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#include <boost/hana/if.hpp>
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namespace hana = boost::hana;
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// This test makes sure that if_ can be used with non-copyable branches.
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template <bool Value>
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struct Boolean { };
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namespace boost { namespace hana {
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template <bool Value>
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struct while_impl<Boolean<Value>> {
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// Not implemented
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};
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template <bool Value>
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struct not_impl<Boolean<Value>> {
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// Not implemented
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};
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template <bool Value>
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struct eval_if_impl<Boolean<Value>> {
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template <typename Cond, typename Then, typename Else>
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static constexpr decltype(auto) apply(Cond const&, Then&& t, Else&& e) {
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return hana::eval_if(hana::bool_c<Value>, static_cast<Then&&>(t),
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static_cast<Else&&>(e));
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}
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};
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}}
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template <int v>
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struct NonCopyable {
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static constexpr int value = v;
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NonCopyable() = default;
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NonCopyable(NonCopyable const&) = delete;
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NonCopyable(NonCopyable&&) = default;
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NonCopyable& operator=(NonCopyable const&) = delete;
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NonCopyable& operator=(NonCopyable&&) = default;
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};
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static_assert(hana::if_(Boolean<true>{}, NonCopyable<3>{}, NonCopyable<4>{}).value == 3, "");
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static_assert(hana::if_(Boolean<false>{}, NonCopyable<3>{}, NonCopyable<4>{}).value == 4, "");
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int main() { }
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