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generator refactoring #1373

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Merged
StephanTLavavej merged 4 commits into from
Oct 17, 2020
Merged

generator refactoring #1373

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generator refactoring
CaseyCarter Oct 5, 2020
38a6346
Curtis's review comments
CaseyCarter Oct 14, 2020
209720a
Casey's review comments
CaseyCarter Oct 14, 2020
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STL's review comments
CaseyCarter Oct 15, 2020
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116 changes: 52 additions & 64 deletions stl/inc/experimental/generator
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Original file line number Diff line number Diff line change
Expand Up @@ -22,7 +22,6 @@
#error <experimental/generator> requires /std:c++latest or /await compiler options
#endif // ^^^ no coroutine support ^^^


#pragma pack(push, _CRT_PACKING)
#pragma warning(push, _STL_WARNING_LEVEL)
#pragma warning(disable : _STL_DISABLED_WARNINGS)
Expand All @@ -33,18 +32,16 @@ _STL_DISABLE_CLANG_WARNINGS
_STD_BEGIN

namespace experimental {

template <typename _Ty, typename _Alloc = allocator<char>>
// NOTE WELL: _CPPUNWIND currently affects the ABI of generator.
template <class _Ty, class _Alloc = allocator<char>>
struct generator {
struct promise_type {
_Ty const* _CurrentValue;
#if 1 // TRANSITION, VSO-1172852
#ifdef _CPPUNWIND
exception_ptr _Eptr;
#endif // _CPPUNWIND
const _Ty* _Value;
#ifdef _CPPUNWIND // TRANSITION, VSO-1172852
exception_ptr _Exception;
#endif // TRANSITION, VSO-1172852

auto get_return_object() {
generator get_return_object() noexcept {
return generator{*this};
}

Expand All @@ -56,38 +53,38 @@ namespace experimental {
return {};
}

#if defined(_CPPUNWIND) || defined(__cpp_impl_coroutine)
void unhandled_exception() noexcept {
#if 1 // TRANSITION, VSO-1172852
#ifndef _KERNEL_MODE
#ifdef _CPPUNWIND
_Eptr = _STD current_exception();
#else // ^^^ _CPPUNWIND / !_CPPUNWIND vvv
abort();
#endif // _CPPUNWIND
#if 1 // TRANSITION, VSO-1172852
void unhandled_exception() noexcept {
_Exception = _STD current_exception();
}
#else // ^^^ workaround / no workaround vvv
void unhandled_exception() {
throw;
#endif // TRANSITION, VSO-1172852
}
#endif // defined(_CPPUNWIND) || defined(__cpp_impl_coroutine)
#endif // TRANSITION, VSO-1172852
#else // ^^^ defined(_CPPUNWIND) / !defined(_CPPUNWIND) vvv
void unhandled_exception() noexcept {}
#endif // _CPPUNWIND
#endif // _KERNEL_MODE

#if 1 // TRANSITION, VSO-1172852
#ifdef _CPPUNWIND // TRANSITION, VSO-1172852
void _Rethrow_if_exception() {
#ifdef _CPPUNWIND
if (_Eptr) {
_STD rethrow_exception(_Eptr);
if (_Exception) {
_STD rethrow_exception(_Exception);
}
#endif // _CPPUNWIND
}
#endif // TRANSITION, VSO-1172852

auto yield_value(_Ty const& _Value) {
_CurrentValue = _STD addressof(_Value);
return suspend_always{};
suspend_always yield_value(const _Ty& _Val) noexcept {
_Value = _STD addressof(_Val);
return {};
}

void return_void() {}
void return_void() noexcept {}

template <typename _Uty>
template <class _Uty>
_Uty&& await_transform(_Uty&& _Whatever) {
static_assert(_Always_false<_Uty>,
"co_await is not supported in coroutines of type std::experimental::generator");
Expand All @@ -98,15 +95,16 @@ namespace experimental {
static_assert(is_same_v<char*, typename allocator_traits<_Alloc_char>::pointer>,
"generator does not support allocators with fancy pointer types");
static_assert(
allocator_traits<_Alloc_char>::is_always_equal::value, "generator only supports stateless allocators");
allocator_traits<_Alloc_char>::is_always_equal::value && is_default_constructible_v<_Alloc_char>,
"generator supports only stateless allocators");

static void* operator new(size_t _Size) {
_Alloc_char _Al;
_Alloc_char _Al{};
return allocator_traits<_Alloc_char>::allocate(_Al, _Size);
}

static void operator delete(void* _Ptr, size_t _Size) noexcept {
_Alloc_char _Al;
_Alloc_char _Al{};
return allocator_traits<_Alloc_char>::deallocate(_Al, static_cast<char*>(_Ptr), _Size);
}
};
Expand All @@ -115,21 +113,19 @@ namespace experimental {
using iterator_category = input_iterator_tag;
using difference_type = ptrdiff_t;
using value_type = _Ty;
using reference = _Ty const&;
using pointer = _Ty const*;
using reference = const _Ty&;
using pointer = const _Ty*;

coroutine_handle<promise_type> _Coro = nullptr;

iterator() = default;
iterator(nullptr_t) : _Coro(nullptr) {}

iterator(coroutine_handle<promise_type> _CoroArg) : _Coro(_CoroArg) {}
explicit iterator(coroutine_handle<promise_type> _Coro_) noexcept : _Coro(_Coro_) {}

iterator& operator++() {
_Coro.resume();
if (_Coro.done()) {
#if 1 // TRANSITION, VSO-1172852
_STD exchange(_Coro, {}).promise()._Rethrow_if_exception();
#ifdef _CPPUNWIND // TRANSITION, VSO-1172852
_STD exchange(_Coro, nullptr).promise()._Rethrow_if_exception();
#else // ^^^ workaround / no workaround vvv
_Coro = nullptr;
#endif // TRANSITION, VSO-1172852
Expand All @@ -139,61 +135,54 @@ namespace experimental {
}

void operator++(int) {
// This postincrement operator meets the requirements of the Ranges TS
// InputIterator concept, but not those of Standard C++ InputIterator.
// This operator meets the requirements of the C++20 input_iterator concept,
// but not the Cpp17InputIterator requirements.
++*this;
}

_NODISCARD bool operator==(iterator const& _Right) const {
_NODISCARD bool operator==(const iterator& _Right) const noexcept {
return _Coro == _Right._Coro;
}

_NODISCARD bool operator!=(iterator const& _Right) const {
_NODISCARD bool operator!=(const iterator& _Right) const noexcept {
return !(*this == _Right);
}

_NODISCARD reference operator*() const {
return *_Coro.promise()._CurrentValue;
_NODISCARD reference operator*() const noexcept {
return *_Coro.promise()._Value;
}

_NODISCARD pointer operator->() const {
return _Coro.promise()._CurrentValue;
_NODISCARD pointer operator->() const noexcept {
return _Coro.promise()._Value;
}
};

_NODISCARD iterator begin() {
if (_Coro) {
_Coro.resume();
if (_Coro.done()) {
#if 1 // TRANSITION, VSO-1172852
#ifdef _CPPUNWIND // TRANSITION, VSO-1172852
_Coro.promise()._Rethrow_if_exception();
#endif // TRANSITION, VSO-1172852
return {nullptr};
return {};
}
}

return {_Coro};
return iterator{_Coro};
}

_NODISCARD iterator end() {
return {nullptr};
_NODISCARD iterator end() noexcept {
return {};
}

explicit generator(promise_type& _Prom) : _Coro(coroutine_handle<promise_type>::from_promise(_Prom)) {}
explicit generator(promise_type& _Prom) noexcept : _Coro(coroutine_handle<promise_type>::from_promise(_Prom)) {}

generator() = default;
generator(generator const&) = delete;
generator& operator=(generator const&) = delete;
generator() = default;

generator(generator&& _Right) : _Coro(_Right._Coro) {
_Right._Coro = nullptr;
}
generator(generator&& _Right) noexcept : _Coro(_STD exchange(_Right._Coro, nullptr)) {}

generator& operator=(generator&& _Right) {
if (this != _STD addressof(_Right)) {
_Coro = _Right._Coro;
_Right._Coro = nullptr;
}
generator& operator=(generator&& _Right) noexcept {
_Coro = _STD exchange(_Right._Coro, nullptr);
return *this;
}

Expand All @@ -206,7 +195,6 @@ namespace experimental {
private:
coroutine_handle<promise_type> _Coro = nullptr;
};

} // namespace experimental

_STD_END
Expand Down