negate.hpp

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// SPDX-License-Identifier: BSL-1.0
// SPDX-FileCopyrightText: Copyright (C) 2019 Tobias Hienzsch
 
#ifndef TETL_FUNCTIONAL_NEGATE_HPP
#define TETL_FUNCTIONAL_NEGATE_HPP
 
#include <etl/_utility/forward.hpp>
 
namespace etl {
 
/// \brief Function object for performing negation. Effectively calls operator-
/// on an instance of type T.
/// https://en.cppreference.com/w/cpp/utility/functional/negate
template <typename T = void>
struct negate {
    [[nodiscard]] constexpr auto operator()(T const& arg) const -> T
    {
        return static_cast<T>(-arg);
    }
};
 
template <>
struct negate<void> {
    using is_transparent = void;
 
    template <typename T>
    [[nodiscard]] constexpr auto operator()(T&& arg) const noexcept(noexcept(-etl::forward<T>(arg)))
        -> decltype(-etl::forward<T>(arg))
    {
        return -etl::forward<T>(arg);
    }
};
 
} // namespace etl
 
#endif // TETL_FUNCTIONAL_NEGATE_HPP