forked from mpusz/mp-units
55 lines
1.8 KiB
C++
55 lines
1.8 KiB
C++
// The MIT License (MIT)
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//
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// Copyright (c) 2018 Mateusz Pusz
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//
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// Permission is hereby granted, free of charge, to any person obtaining a copy
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// of this software and associated documentation files (the "Software"), to deal
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// in the Software without restriction, including without limitation the rights
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// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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// copies of the Software, and to permit persons to whom the Software is
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// furnished to do so, subject to the following conditions:
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//
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// The above copyright notice and this permission notice shall be included in all
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// copies or substantial portions of the Software.
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//
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// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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// SOFTWARE.
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#pragma once
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#include <units/bits/hacks.h>
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#include <type_traits>
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namespace std::experimental::units {
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template<typename BaseType>
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struct downcast_base {
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using base_type = BaseType;
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};
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template<typename T>
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concept bool Downcastable =
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requires {
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typename T::base_type;
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} &&
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std::derived_from<T, downcast_base<typename T::base_type>>;
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template<Downcastable T>
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using downcast_from = T::base_type;
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template<Downcastable T>
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using downcast_to = std::type_identity<T>;
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template<Downcastable T>
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struct downcasting_traits : downcast_to<T> {};
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template<Downcastable T>
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using downcasting_traits_t = downcasting_traits<T>::type;
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} // namespace std::experimental::units
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