74 lines
2.7 KiB
C++
74 lines
2.7 KiB
C++
////////////////////////////////////////////////////////////////////////////////
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/// \file enable_overload.hpp
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///
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/// \brief This internal header provides the definition of a SFINAE utility
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/// for conditionally enabling overloads
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////////////////////////////////////////////////////////////////////////////////
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/*
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The MIT License (MIT)
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Copyright (c) 2020 Matthew Rodusek All rights reserved.
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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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The above copyright notice and this permission notice shall be included in
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all copies or substantial portions of the Software.
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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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*/
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#ifndef BPSTD_DETAIL_ENABLE_OVERLOAD_HPP
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#define BPSTD_DETAIL_ENABLE_OVERLOAD_HPP
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#if defined(_MSC_VER) && (_MSC_VER >= 1200)
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# pragma once
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#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
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namespace bpstd {
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namespace detail {
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/// \brief Similar to enable_if, but doesn't sfinae-away a type; instead
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/// produces an uninstantiable unique type when true
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///
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/// This is used to selectively disable constructors, since sfinae doesn't
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/// work for copy/move constructors
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template <bool b, typename T>
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struct enable_overload_if
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{
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using type = T;
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};
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template <typename T>
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struct enable_overload_if<false,T>
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{
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class type{ type() = delete; ~type() = delete; };
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};
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template <bool B, typename T>
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using enable_overload_if_t = typename enable_overload_if<B,T>::type;
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/// \brief Inverse of enable_overload_if
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template <bool B, typename T>
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using disable_overload_if = enable_overload_if<!B,T>;
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/// \brief Convenience alias to retrieve the ::type member of
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/// disable_overload_if
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template <bool B, typename T>
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using disable_overload_if_t = typename disable_overload_if<B,T>::type;
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} // namespace detail
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} // namespace bpstd
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#endif /* BPSTD_DETAIL_ENABLE_OVERLOAD_HPP */
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