BorrowedFd.hpp

// SPDX-FileCopyrightText: 2025 Vincent Leroy
// SPDX-License-Identifier: MIT
//
// This file is part of dfx.
//
// Licensed under the MIT License. See the LICENSE file in the project root
// for full license information.
 
#pragma once
 
// Standard includes
#include <format>
 
// Project includes
#include <dfx-utilities/CopyMoveControl.hpp>
 
namespace dfx::FdWatch
{
class PollerFd;
class OwnedFd;
 

class BorrowedFd
{
public:
    BorrowedFd() noexcept = default;

    explicit BorrowedFd(PollerFd const & fd) noexcept;

    explicit BorrowedFd(OwnedFd const & fd) noexcept;

    explicit BorrowedFd(int fd) noexcept;
 
    ENABLE_DEFAULT_COPY_AND_MOVE_NOEXCEPT(BorrowedFd);
 
    void swap(BorrowedFd & other) noexcept;
 
    bool operator==(BorrowedFd const & fd) const noexcept { return _fd == fd._fd; }
    bool operator==(int fd) const noexcept                { return _fd == fd; }
 
public:
    int get() const noexcept      { return _fd; }

    bool isValid() const noexcept { return _fd != -1; }

    void reset() noexcept         { _fd = -1; }
 
private:
    int _fd = -1;
};
 
inline void swap(BorrowedFd & fd1, BorrowedFd & fd2) noexcept { fd1.swap(fd2); }
} // !namespace dfx::FdWatch
 
template<>
struct std::formatter<dfx::FdWatch::BorrowedFd> : public formatter<int>
{
    auto format(dfx::FdWatch::BorrowedFd const & e, format_context & ctx) const
    { return formatter<int>::format(e.get(), ctx); }
};
 
template<>
struct std::hash<dfx::FdWatch::BorrowedFd>
{
    std::size_t operator()(dfx::FdWatch::BorrowedFd const & fd) const noexcept
    { return static_cast<std::size_t>(fd.get()); }
};