coroutine.h
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#pragma once
namespace std { namespace experimental { inline namespace coroutines_v1 {
template <typename R, typename...> struct coroutine_traits {
using promise_type = typename R::promise_type;
};
template <typename Promise = void> struct coroutine_handle;
template <> struct coroutine_handle<void> {
static coroutine_handle from_address(void *addr) noexcept {
coroutine_handle me;
me.ptr = addr;
return me;
}
void operator()() { resume(); }
void *address() const noexcept { return ptr; }
void resume() const { __builtin_coro_resume(ptr); }
void destroy() const { __builtin_coro_destroy(ptr); }
bool done() const { return __builtin_coro_done(ptr); }
coroutine_handle &operator=(decltype(nullptr)) {
ptr = nullptr;
return *this;
}
coroutine_handle(decltype(nullptr)) : ptr(nullptr) {}
coroutine_handle() : ptr(nullptr) {}
// void reset() { ptr = nullptr; } // add to P0057?
explicit operator bool() const { return ptr; }
protected:
void *ptr;
};
template <typename Promise> struct coroutine_handle : coroutine_handle<> {
using coroutine_handle<>::operator=;
static coroutine_handle from_address(void *addr) noexcept {
coroutine_handle me;
me.ptr = addr;
return me;
}
Promise &promise() const {
return *reinterpret_cast<Promise *>(
__builtin_coro_promise(ptr, alignof(Promise), false));
}
static coroutine_handle from_promise(Promise &promise) {
coroutine_handle p;
p.ptr = __builtin_coro_promise(&promise, alignof(Promise), true);
return p;
}
};
template <typename _PromiseT>
bool operator==(coroutine_handle<_PromiseT> const& _Left,
coroutine_handle<_PromiseT> const& _Right) noexcept
{
return _Left.address() == _Right.address();
}
template <typename _PromiseT>
bool operator!=(coroutine_handle<_PromiseT> const& _Left,
coroutine_handle<_PromiseT> const& _Right) noexcept
{
return !(_Left == _Right);
}
struct suspend_always {
bool await_ready() { return false; }
void await_suspend(coroutine_handle<>) {}
void await_resume() {}
};
struct suspend_never {
bool await_ready() noexcept { return true; }
void await_suspend(coroutine_handle<>) noexcept {}
void await_resume() noexcept {}
};
}}}