// Copyright 2019 Hans Dembinski
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//
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// Distributed under the Boost Software License, Version 1.0.
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// (See accompanying file LICENSE_1_0.txt
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// or copy at http://www.boost.org/LICENSE_1_0.txt)
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#ifndef BOOST_HISTOGRAM_DETAIL_NOOP_MUTEX_HPP
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#define BOOST_HISTOGRAM_DETAIL_NOOP_MUTEX_HPP
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#include <boost/core/empty_value.hpp>
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#include <boost/histogram/detail/axes.hpp>
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#include <boost/mp11/utility.hpp> // mp_if
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#include <mutex>
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namespace boost {
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namespace histogram {
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namespace detail {
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struct null_mutex {
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bool try_lock() noexcept { return true; }
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void lock() noexcept {}
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void unlock() noexcept {}
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};
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template <class Axes, class Storage,
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class DetailMutex = mp11::mp_if_c<(Storage::has_threading_support &&
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detail::has_growing_axis<Axes>::value),
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std::mutex, detail::null_mutex>>
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struct mutex_base : empty_value<DetailMutex> {
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mutex_base() = default;
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// do not copy or move mutex
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mutex_base(const mutex_base&) : empty_value<DetailMutex>() {}
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// do not copy or move mutex
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mutex_base& operator=(const mutex_base&) { return *this; }
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};
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} // namespace detail
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} // namespace histogram
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} // namespace boost
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#endif
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