Preview: coroutine
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//opt/rh/gcc-toolset-14/root/usr/include/c++/14/coroutine
// <coroutine> -*- C++ -*-
// Copyright (C) 2019-2024 Free Software Foundation, Inc.
//
// This file is part of the GNU ISO C++ Library. This library is free
// software; you can redistribute it and/or modify it under the
// terms of the GNU General Public License as published by the
// Free Software Foundation; either version 3, or (at your option)
// any later version.
// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
// Under Section 7 of GPL version 3, you are granted additional
// permissions described in the GCC Runtime Library Exception, version
// 3.1, as published by the Free Software Foundation.
// You should have received a copy of the GNU General Public License and
// a copy of the GCC Runtime Library Exception along with this program;
// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
// <http://www.gnu.org/licenses/>.
/** @file include/coroutine
* This is a Standard C++ Library header.
*/
#ifndef _GLIBCXX_COROUTINE
#define _GLIBCXX_COROUTINE 1
#pragma GCC system_header
#define __glibcxx_want_coroutine
#include <bits/version.h>
#if !__cpp_impl_coroutine
# error "the <coroutine> header requires -fcoroutines"
#endif
#ifdef __cpp_lib_coroutine // C++ >= 14 && impl_coroutine
#include <type_traits>
#if __cplusplus > 201703L
# include <compare>
#endif
#if !defined __cpp_lib_three_way_comparison
# include <bits/stl_function.h> // for std::less
#endif
/**
* @defgroup coroutines Coroutines
*
* Components for supporting coroutine implementations.
*
* @since C++20 (and since C++14 as a libstdc++ extension)
*/
namespace std _GLIBCXX_VISIBILITY (default)
{
_GLIBCXX_BEGIN_NAMESPACE_VERSION
inline namespace __n4861 {
// C++20 17.12.2 coroutine traits
/// [coroutine.traits]
/// [coroutine.traits.primary]
/// If _Result::promise_type is valid and denotes a type then the traits
/// have a single publicly accessible member, otherwise they are empty.
template <typename _Result, typename... _ArgTypes>
struct coroutine_traits;
template <typename _Result, typename = void>
struct __coroutine_traits_impl {};
template <typename _Result>
#if __cpp_concepts
requires requires { typename _Result::promise_type; }
struct __coroutine_traits_impl<_Result, void>
#else
struct __coroutine_traits_impl<_Result,
__void_t<typename _Result::promise_type>>
#endif
{
using promise_type = typename _Result::promise_type;
};
template <typename _Result, typename... _ArgTypes>
struct coroutine_traits : __coroutine_traits_impl<_Result> {};
// C++20 17.12.3 Class template coroutine_handle
/// [coroutine.handle]
template <typename _Promise = void>
struct coroutine_handle;
template <> struct
coroutine_handle<void>
{
public:
// [coroutine.handle.con], construct/reset
constexpr coroutine_handle() noexcept : _M_fr_ptr(nullptr) {}
constexpr coroutine_handle(std::nullptr_t __h) noexcept
: _M_fr_ptr(__h)
{}
coroutine_handle& operator=(std::nullptr_t) noexcept
{
_M_fr_ptr = nullptr;
return *this;
}
public:
// [coroutine.handle.export.import], export/import
constexpr void* address() const noexcept { return _M_fr_ptr; }
constexpr static coroutine_handle from_address(void* __a) noexcept
{
coroutine_handle __self;
__self._M_fr_ptr = __a;
return __self;
}
public:
// [coroutine.handle.observers], observers
constexpr explicit operator bool() const noexcept
{
return bool(_M_fr_ptr);
}
bool done() const noexcept { return __builtin_coro_done(_M_fr_ptr); }
// [coroutine.handle.resumption], resumption
void operator()() const { resume(); }
void resume() const { __builtin_coro_resume(_M_fr_ptr); }
void destroy() const { __builtin_coro_destroy(_M_fr_ptr); }
protected:
void* _M_fr_ptr;
};
// [coroutine.handle.compare], comparison operators
constexpr bool
operator==(coroutine_handle<> __a, coroutine_handle<> __b) noexcept
{
return __a.address() == __b.address();
}
#ifdef __cpp_lib_three_way_comparison
constexpr strong_ordering
operator<=>(coroutine_handle<> __a, coroutine_handle<> __b) noexcept
{
return std::compare_three_way()(__a.address(), __b.address());
}
#else
// These are to enable operation with std=c++14,17.
constexpr bool
operator!=(coroutine_handle<> __a, coroutine_handle<> __b) noexcept
{
return !(__a == __b);
}
constexpr bool
operator<(coroutine_handle<> __a, coroutine_handle<> __b) noexcept
{
return less<void*>()(__a.address(), __b.address());
}
constexpr bool
operator>(coroutine_handle<> __a, coroutine_handle<> __b) noexcept
{
return __b < __a;
}
constexpr bool
operator<=(coroutine_handle<> __a, coroutine_handle<> __b) noexcept
{
return !(__a > __b);
}
constexpr bool
operator>=(coroutine_handle<> __a, coroutine_handle<> __b) noexcept
{
return !(__a < __b);
}
#endif
template <typename _Promise>
struct coroutine_handle
{
// [coroutine.handle.con], construct/reset
constexpr coroutine_handle() noexcept { }
constexpr coroutine_handle(nullptr_t) noexcept { }
static coroutine_handle
from_promise(_Promise& __p)
{
coroutine_handle __self;
__self._M_fr_ptr
= __builtin_coro_promise((char*) &__p, __alignof(_Promise), true);
return __self;
}
coroutine_handle& operator=(nullptr_t) noexcept
{
_M_fr_ptr = nullptr;
return *this;
}
// [coroutine.handle.export.import], export/import
constexpr void* address() const noexcept { return _M_fr_ptr; }
constexpr static coroutine_handle from_address(void* __a) noexcept
{
coroutine_handle __self;
__self._M_fr_ptr = __a;
return __self;
}
// [coroutine.handle.conv], conversion
constexpr operator coroutine_handle<>() const noexcept
{ return coroutine_handle<>::from_address(address()); }
// [coroutine.handle.observers], observers
constexpr explicit operator bool() const noexcept
{
return bool(_M_fr_ptr);
}
bool done() const noexcept { return __builtin_coro_done(_M_fr_ptr); }
// [coroutine.handle.resumption], resumption
void operator()() const { resume(); }
void resume() const { __builtin_coro_resume(_M_fr_ptr); }
void destroy() const { __builtin_coro_destroy(_M_fr_ptr); }
// [coroutine.handle.promise], promise access
_Promise& promise() const
{
void* __t
= __builtin_coro_promise (_M_fr_ptr, __alignof(_Promise), false);
return *static_cast<_Promise*>(__t);
}
private:
void* _M_fr_ptr = nullptr;
};
/// [coroutine.noop]
struct noop_coroutine_promise
{
};
// 17.12.4.1 Class noop_coroutine_promise
/// [coroutine.promise.noop]
template <>
struct coroutine_handle<noop_coroutine_promise>
{
// _GLIBCXX_RESOLVE_LIB_DEFECTS
// 3460. Unimplementable noop_coroutine_handle guarantees
// [coroutine.handle.noop.conv], conversion
constexpr operator coroutine_handle<>() const noexcept
{ return coroutine_handle<>::from_address(address()); }
// [coroutine.handle.noop.observers], observers
constexpr explicit operator bool() const noexcept { return true; }
constexpr bool done() const noexcept { return false; }
// [coroutine.handle.noop.resumption], resumption
void operator()() const noexcept {}
void resume() const noexcept {}
void destroy() const noexcept {}
// [coroutine.handle.noop.promise], promise access
noop_coroutine_promise& promise() const noexcept
{ return _S_fr.__p; }
// [coroutine.handle.noop.address], address
constexpr void* address() const noexcept { return _M_fr_ptr; }
private:
friend coroutine_handle noop_coroutine() noexcept;
struct __frame
{
static void __dummy_resume_destroy() { }
void (*__r)() = __dummy_resume_destroy;
void (*__d)() = __dummy_resume_destroy;
struct noop_coroutine_promise __p;
};
static __frame _S_fr;
explicit coroutine_handle() noexcept = default;
void* _M_fr_ptr = &_S_fr;
};
using noop_coroutine_handle = coroutine_handle<noop_coroutine_promise>;
inline noop_coroutine_handle::__frame
noop_coroutine_handle::_S_fr{};
inline noop_coroutine_handle noop_coroutine() noexcept
{
return noop_coroutine_handle();
}
// 17.12.5 Trivial awaitables
/// [coroutine.trivial.awaitables]
struct suspend_always
{
constexpr bool await_ready() const noexcept { return false; }
constexpr void await_suspend(coroutine_handle<>) const noexcept {}
constexpr void await_resume() const noexcept {}
};
struct suspend_never
{
constexpr bool await_ready() const noexcept { return true; }
constexpr void await_suspend(coroutine_handle<>) const noexcept {}
constexpr void await_resume() const noexcept {}
};
} // namespace __n4861
template<typename _Tp> struct hash;
template<typename _Promise>
struct hash<coroutine_handle<_Promise>>
{
size_t
operator()(const coroutine_handle<_Promise>& __h) const noexcept
{
return reinterpret_cast<size_t>(__h.address());
}
};
_GLIBCXX_END_NAMESPACE_VERSION
} // namespace std
#endif // __cpp_lib_coroutine
#endif // _GLIBCXX_COROUTINE
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