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include/boost/atomic/posix_clock_traits_fwd.hpp

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+/*
+ * Distributed under the Boost Software License, Version 1.0.
+ * (See accompanying file LICENSE_1_0.txt or copy at
+ * http://www.boost.org/LICENSE_1_0.txt)
+ *
+ * Copyright (c) 2025 Andrey Semashev
+ */
+/*!
+ * \file   atomic/posix_clock_traits_fwd.hpp
+ *
+ * This header contains declaration of the \c posix_clock_traits class template.
+ */
+
+#ifndef BOOST_ATOMIC_POSIX_CLOCK_TRAITS_FWD_HPP_INCLUDED_
+#define BOOST_ATOMIC_POSIX_CLOCK_TRAITS_FWD_HPP_INCLUDED_
+
+#include <boost/atomic/detail/config.hpp>
+#include <boost/atomic/detail/header.hpp>
+
+#ifdef BOOST_HAS_PRAGMA_ONCE
+#pragma once
+#endif
+
+namespace boost {
+namespace atomics {
+
+/*!
+ * \brief The structure contains traits for compatibility between chrono clocks and POSIX clocks.
+ *
+ * This class template is meant to be specialized for clock types that are compatible with `std::chrono`
+ * requirements and are based on one of the POSIX clocks identified by
+ * a [`clockid_t`](https://man7.org/linux/man-pages/man3/clockid_t.3type.html) constant.
+ *
+ * Every specialization of this class must support the following interface:
+ *
+ * ```
+ * // POSIX clock identifier
+ * static constexpr clockid_t clock_id = ...;
+ *
+ * // Function that converts a time point to a timespec structure
+ * static timespec to_timespec(Clock::time_point time_point) noexcept;
+ * ```
+ *
+ * Note that the `timespec` structure returned from `to_timespec` must use the identified POSIX
+ * clock epoch and time units. There are no invalid input `time_point` values, so `to_timespec`
+ * must never fail with an exception.
+ *
+ * The second template parameter of this class template may be used by partial specializations
+ * to leverage SFINAE to selectively enable it for a set of clock types.
+ */
+template< typename Clock, typename = void >
+struct posix_clock_traits;
+
+} // namespace atomics
+} // namespace boost
+
+#include <boost/atomic/detail/footer.hpp>
+
+#endif // BOOST_ATOMIC_POSIX_CLOCK_TRAITS_FWD_HPP_INCLUDED_