equal_to.hpp

Go to the documentation of this file.

// SPDX-License-Identifier: BSL-1.0
// SPDX-FileCopyrightText: Copyright (C) 2019 Tobias Hienzsch
 
#ifndef TETL_FUNCTIONAL_EQUAL_TO_HPP
#define TETL_FUNCTIONAL_EQUAL_TO_HPP
 
#include <etl/_utility/forward.hpp>
 
namespace etl {
 
/// \brief Function object for performing comparisons. Unless specialised,
/// invokes operator== on type T.
/// https://en.cppreference.com/w/cpp/utility/functional/equal_to
template <typename T = void>
struct equal_to {
    [[nodiscard]] constexpr auto operator()(T const& lhs, T const& rhs) const -> bool
    {
        return lhs == rhs;
    }
};
 
template <>
struct equal_to<void> {
    using is_transparent = void;
 
    template <typename T, typename U>
    [[nodiscard]] constexpr auto
    operator()(T&& lhs, U&& rhs) const noexcept(noexcept(etl::forward<T>(lhs) == etl::forward<U>(rhs)))
        -> decltype(etl::forward<T>(lhs) == etl::forward<U>(rhs))
    {
        return etl::forward<T>(lhs) == etl::forward<U>(rhs);
    }
};
 
} // namespace etl
 
#endif // TETL_FUNCTIONAL_EQUAL_TO_HPP