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[libc++] Implement stop_token
Implement stop_token http://eel.is/c++draft/thread.stoptoken
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‎libcxx/docs/Status/Cxx20.rst

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@@ -50,6 +50,7 @@ Paper Status
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.. [#note-P0883.2] P0883: ``ATOMIC_FLAG_INIT`` was marked deprecated in version 14.0, but was undeprecated with the implementation of LWG3659 in version 15.0.
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.. [#note-P2231] P2231: Optional is complete. The changes to variant haven't been implemented yet.
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.. [#note-P0408] P0408: Only `view()` members implemented.
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.. [#note-P0660] P0660: Section 32.3 Stop Tokens is complete. ``jthread`` hasn't been implemented yet.
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.. _issues-status-cxx20:
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‎libcxx/docs/Status/Cxx20Issues.csv

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"`3250 <https://wg21.link/LWG3250>`__","``std::format``\ : ``#``\ (alternate form) for NaN and inf","Prague","|Complete|","14.0","|format|"
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"`3251 <https://wg21.link/LWG3251>`__","Are ``std::format``\ alignment specifiers applied to string arguments?","Prague","|Complete|","14.0","|format|"
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"`3252 <https://wg21.link/LWG3252>`__","Parse locale's aware modifiers for commands are not consistent with POSIX spec","Prague","","","|chrono|"
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"`3254 <https://wg21.link/LWG3254>`__","Strike ``stop_token``\ 's ``operator!=``\ ","Prague","",""
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"`3254 <https://wg21.link/LWG3254>`__","Strike ``stop_token``\ 's ``operator!=``\ ","Prague","|Complete|","17.0"
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"`3255 <https://wg21.link/LWG3255>`__","``span``\ 's ``array``\ constructor is too strict","Prague","|Complete|",""
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"`3260 <https://wg21.link/LWG3260>`__","``year_month*``\ arithmetic rejects durations convertible to years","Prague","","","|chrono|"
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"`3262 <https://wg21.link/LWG3262>`__","Formatting of negative durations is not specified","Prague","|Complete|","16.0","|chrono| |format|"

‎libcxx/docs/Status/Cxx20Papers.csv

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"`P0553R4 <https://wg21.link/P0553R4>`__","LWG","Bit operations","Cologne","|Complete|","9.0"
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"`P0631R8 <https://wg21.link/P0631R8>`__","LWG","Math Constants","Cologne","|Complete|","11.0"
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"`P0645R10 <https://wg21.link/P0645R10>`__","LWG","Text Formatting","Cologne","|Complete| [#note-P0645]_","14.0"
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"`P0660R10 <https://wg21.link/P0660R10>`__","LWG","Stop Token and Joining Thread, Rev 10","Cologne","",""
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"`P0660R10 <https://wg21.link/P0660R10>`__","LWG","Stop Token and Joining Thread, Rev 10.","Cologne","|In Progress| [#note-P0660]_",""
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"`P0784R7 <https://wg21.link/P0784R7>`__","CWG","More constexpr containers","Cologne","|Complete|","12.0"
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"`P0980R1 <https://wg21.link/P0980R1>`__","LWG","Making std::string constexpr","Cologne","|Complete|","15.0"
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"`P1004R2 <https://wg21.link/P1004R2>`__","LWG","Making std::vector constexpr","Cologne","|Complete|","15.0"

‎libcxx/include/CMakeLists.txt

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__stop_token/atomic_unique_lock.h
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__stop_token/intrusive_list_view.h
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__stop_token/intrusive_shared_ptr.h
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__stop_token/stop_callback.h
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__stop_token/stop_source.h
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__stop_token/stop_state.h
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__stop_token/stop_token.h
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__string/char_traits.h
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__string/constexpr_c_functions.h
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__string/extern_template_lists.h
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stdint.h
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stdio.h
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stdlib.h
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stop_token
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streambuf
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string
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string.h

‎libcxx/include/__stop_token/atomic_unique_lock.h

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// where State contains a lock bit and might contain other data,
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// and LockedBit is the value of State when the lock bit is set, e.g 1 << 2
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template <class _State, _State _LockedBit>
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class __atomic_unique_lock {
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class _LIBCPP_AVAILABILITY_SYNC __atomic_unique_lock {
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static_assert(std::popcount(_LockedBit) == 1, "LockedBit must be an integer where only one bit is set");
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std::atomic<_State>& __state_;

‎libcxx/include/__stop_token/stop_callback.h

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// -*- C++ -*-
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//===----------------------------------------------------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#ifndef _LIBCPP___STOP_TOKEN_STOP_CALLBACK_H
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#define _LIBCPP___STOP_TOKEN_STOP_CALLBACK_H
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#include <__availability>
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#include <__concepts/constructible.h>
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#include <__concepts/destructible.h>
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#include <__concepts/invocable.h>
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#include <__config>
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#include <__stop_token/intrusive_shared_ptr.h>
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#include <__stop_token/stop_state.h>
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#include <__stop_token/stop_token.h>
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#include <__type_traits/is_nothrow_constructible.h>
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#include <__utility/forward.h>
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#include <__utility/move.h>
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#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
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# pragma GCC system_header
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#endif
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_LIBCPP_BEGIN_NAMESPACE_STD
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#if _LIBCPP_STD_VER >= 20
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template <class _Callback>
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class _LIBCPP_AVAILABILITY_SYNC stop_callback : private __stop_callback_base {
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static_assert(invocable<_Callback>,
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"Mandates: stop_callback is instantiated with an argument for the template parameter Callback that "
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"satisfies invocable.");
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static_assert(destructible<_Callback>,
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"Mandates: stop_callback is instantiated with an argument for the template parameter Callback that "
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"satisfies destructible.");
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public:
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using callback_type = _Callback;
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template <class _Cb>
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requires constructible_from<_Callback, _Cb>
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_LIBCPP_HIDE_FROM_ABI explicit stop_callback(const stop_token& __st,
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_Cb&& __cb) noexcept(is_nothrow_constructible_v<_Callback, _Cb>)
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: stop_callback(__private_tag{}, __st.__state_, std::forward<_Cb>(__cb)) {}
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template <class _Cb>
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requires constructible_from<_Callback, _Cb>
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_LIBCPP_HIDE_FROM_ABI explicit stop_callback(stop_token&& __st,
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_Cb&& __cb) noexcept(is_nothrow_constructible_v<_Callback, _Cb>)
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: stop_callback(__private_tag{}, std::move(__st.__state_), std::forward<_Cb>(__cb)) {}
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_LIBCPP_HIDE_FROM_ABI ~stop_callback() {
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if (__state_) {
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__state_->__remove_callback(this);
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}
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}
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stop_callback(const stop_callback&) = delete;
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stop_callback(stop_callback&&) = delete;
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stop_callback& operator=(const stop_callback&) = delete;
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stop_callback& operator=(stop_callback&&) = delete;
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private:
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_LIBCPP_NO_UNIQUE_ADDRESS _Callback __callback_;
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__intrusive_shared_ptr<__stop_state> __state_;
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friend __stop_callback_base;
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struct __private_tag {};
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template <class _StatePtr, class _Cb>
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_LIBCPP_HIDE_FROM_ABI explicit stop_callback(__private_tag, _StatePtr&& __state, _Cb&& __cb) noexcept(
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is_nothrow_constructible_v<_Callback, _Cb>)
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: __stop_callback_base([](__stop_callback_base* __cb_base) noexcept {
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// stop callback is supposed to only be called once
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std::forward<_Callback>(static_cast<stop_callback*>(__cb_base)->__callback_)();
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}),
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__callback_(std::forward<_Cb>(__cb)),
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__state_() {
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if (__state && __state->__add_callback(this)) {
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// st.stop_requested() was false and this is successfully added to the linked list
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__state_ = std::forward<_StatePtr>(__state);
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}
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}
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};
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template <class Callback>
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_LIBCPP_AVAILABILITY_SYNC stop_callback(stop_token, Callback) -> stop_callback<Callback>;
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#endif // _LIBCPP_STD_VER >= 20
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_LIBCPP_END_NAMESPACE_STD
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#endif // _LIBCPP___STOP_TOKEN_STOP_TOKEN_H

‎libcxx/include/__stop_token/stop_source.h

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// -*- C++ -*-
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//===----------------------------------------------------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#ifndef _LIBCPP___STOP_TOKEN_STOP_SOURCE_H
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#define _LIBCPP___STOP_TOKEN_STOP_SOURCE_H
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#include <__availability>
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#include <__config>
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#include <__stop_token/intrusive_shared_ptr.h>
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#include <__stop_token/stop_state.h>
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#include <__stop_token/stop_token.h>
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#include <__utility/move.h>
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#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
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# pragma GCC system_header
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#endif
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_LIBCPP_BEGIN_NAMESPACE_STD
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#if _LIBCPP_STD_VER >= 20
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struct nostopstate_t {
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explicit nostopstate_t() = default;
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};
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inline constexpr nostopstate_t nostopstate{};
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class _LIBCPP_AVAILABILITY_SYNC stop_source {
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public:
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_LIBCPP_HIDE_FROM_ABI stop_source() : __state_(new __stop_state()) { __state_->__increment_stop_source_counter(); }
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_LIBCPP_HIDE_FROM_ABI explicit stop_source(nostopstate_t) noexcept : __state_(nullptr) {}
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_LIBCPP_HIDE_FROM_ABI stop_source(const stop_source& __other) noexcept : __state_(__other.__state_) {
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if (__state_) {
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__state_->__increment_stop_source_counter();
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}
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}
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_LIBCPP_HIDE_FROM_ABI stop_source(stop_source&& __other) noexcept = default;
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_LIBCPP_HIDE_FROM_ABI stop_source& operator=(const stop_source& __other) noexcept {
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// increment `__other` first so that we don't hit 0 in case of self-assignment
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if (__other.__state_) {
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__other.__state_->__increment_stop_source_counter();
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}
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if (__state_) {
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__state_->__decrement_stop_source_counter();
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}
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__state_ = __other.__state_;
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return *this;
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}
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_LIBCPP_HIDE_FROM_ABI stop_source& operator=(stop_source&&) noexcept = default;
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_LIBCPP_HIDE_FROM_ABI ~stop_source() {
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if (__state_) {
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__state_->__decrement_stop_source_counter();
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}
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}
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_LIBCPP_HIDE_FROM_ABI void swap(stop_source& __other) noexcept { __state_.swap(__other.__state_); }
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[[nodiscard]] _LIBCPP_HIDE_FROM_ABI stop_token get_token() const noexcept { return stop_token(__state_); }
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[[nodiscard]] _LIBCPP_HIDE_FROM_ABI bool stop_possible() const noexcept { return __state_ != nullptr; }
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[[nodiscard]] _LIBCPP_HIDE_FROM_ABI bool stop_requested() const noexcept {
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return __state_ != nullptr && __state_->__stop_requested();
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}
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_LIBCPP_HIDE_FROM_ABI bool request_stop() noexcept { return __state_ && __state_->__request_stop(); }
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[[nodiscard]] _LIBCPP_HIDE_FROM_ABI friend bool operator==(const stop_source&, const stop_source&) noexcept = default;
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_LIBCPP_HIDE_FROM_ABI friend void swap(stop_source& __lhs, stop_source& __rhs) noexcept { __lhs.swap(__rhs); }
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private:
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__intrusive_shared_ptr<__stop_state> __state_;
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};
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#endif // _LIBCPP_STD_VER >= 20
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_LIBCPP_END_NAMESPACE_STD
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#endif // _LIBCPP___STOP_TOKEN_STOP_SOURCE_H

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