| /* |
| * Copyright (c) 2021-2022 Facebook, Inc. and its affiliates |
| * Copyright (c) 2021-2022 NVIDIA Corporation |
| * |
| * Licensed under the Apache License Version 2.0 with LLVM Exceptions |
| * (the "License"); you may not use this file except in compliance with |
| * the License. You may obtain a copy of the License at |
| * |
| * https://llvm.org/LICENSE.txt |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| #pragma once |
| |
| #include "__config.hpp" |
| |
| #include <cassert> |
| #include <cstddef> |
| #include <utility> |
| |
| namespace stdexec |
| { |
| namespace __queue |
| { |
| template <auto _Next> |
| class __intrusive_queue; |
| |
| template <class _Item, _Item* _Item::*_Next> |
| class __intrusive_queue<_Next> |
| { |
| public: |
| __intrusive_queue() noexcept = default; |
| |
| __intrusive_queue(__intrusive_queue&& __other) noexcept : |
| __head_(std::exchange(__other.__head_, nullptr)), |
| __tail_(std::exchange(__other.__tail_, nullptr)) |
| {} |
| |
| __intrusive_queue(_Item* __head, _Item* __tail) noexcept : |
| __head_(__head), __tail_(__tail) |
| {} |
| |
| __intrusive_queue& operator=(__intrusive_queue __other) noexcept |
| { |
| std::swap(__head_, __other.__head_); |
| std::swap(__tail_, __other.__tail_); |
| return *this; |
| } |
| |
| ~__intrusive_queue() |
| { |
| STDEXEC_ASSERT(empty()); |
| } |
| |
| static __intrusive_queue make_reversed(_Item* __list) noexcept |
| { |
| _Item* __new_head = nullptr; |
| _Item* __new_tail = __list; |
| while (__list != nullptr) |
| { |
| _Item* __next = __list->*_Next; |
| __list->*_Next = __new_head; |
| __new_head = __list; |
| __list = __next; |
| } |
| |
| __intrusive_queue __result; |
| __result.__head_ = __new_head; |
| __result.__tail_ = __new_tail; |
| return __result; |
| } |
| |
| static __intrusive_queue make(_Item* __list) noexcept |
| { |
| __intrusive_queue __result{}; |
| __result.__head_ = __list; |
| __result.__tail_ = __list; |
| if (__list == nullptr) |
| { |
| return __result; |
| } |
| while (__result.__tail_->*_Next != nullptr) |
| { |
| __result.__tail_ = __result.__tail_->*_Next; |
| } |
| return __result; |
| } |
| |
| [[nodiscard]] bool empty() const noexcept |
| { |
| return __head_ == nullptr; |
| } |
| |
| void clear() noexcept |
| { |
| __head_ = nullptr; |
| __tail_ = nullptr; |
| } |
| |
| [[nodiscard]] _Item* pop_front() noexcept |
| { |
| STDEXEC_ASSERT(!empty()); |
| _Item* __item = std::exchange(__head_, __head_->*_Next); |
| // This should test if __head_ == nullptr, but due to a bug in |
| // nvc++'s optimization, `__head_` isn't assigned until later. |
| // Filed as NVBug#3952534. |
| if (__item->*_Next == nullptr) |
| { |
| __tail_ = nullptr; |
| } |
| return __item; |
| } |
| |
| void push_front(_Item* __item) noexcept |
| { |
| STDEXEC_ASSERT(__item != nullptr); |
| __item->*_Next = __head_; |
| __head_ = __item; |
| if (__tail_ == nullptr) |
| { |
| __tail_ = __item; |
| } |
| } |
| |
| void push_back(_Item* __item) noexcept |
| { |
| STDEXEC_ASSERT(__item != nullptr); |
| __item->*_Next = nullptr; |
| if (__tail_ == nullptr) |
| { |
| __head_ = __item; |
| } |
| else |
| { |
| __tail_->*_Next = __item; |
| } |
| __tail_ = __item; |
| } |
| |
| void append(__intrusive_queue __other) noexcept |
| { |
| if (__other.empty()) |
| return; |
| auto* __other_head = std::exchange(__other.__head_, nullptr); |
| if (empty()) |
| { |
| __head_ = __other_head; |
| } |
| else |
| { |
| __tail_->*_Next = __other_head; |
| } |
| __tail_ = std::exchange(__other.__tail_, nullptr); |
| } |
| |
| void prepend(__intrusive_queue __other) noexcept |
| { |
| if (__other.empty()) |
| return; |
| |
| __other.__tail_->*_Next = __head_; |
| __head_ = __other.__head_; |
| if (__tail_ == nullptr) |
| { |
| __tail_ = __other.__tail_; |
| } |
| |
| __other.__tail_ = nullptr; |
| __other.__head_ = nullptr; |
| } |
| |
| struct iterator |
| { |
| using difference_type = std::ptrdiff_t; |
| using value_type = _Item*; |
| |
| _Item* __predecessor_ = nullptr; |
| _Item* __item_ = nullptr; |
| |
| iterator() noexcept = default; |
| |
| explicit iterator(_Item* __pred, _Item* __item) noexcept : |
| __predecessor_(__pred), __item_(__item) |
| {} |
| |
| [[nodiscard]] _Item* operator*() const noexcept |
| { |
| STDEXEC_ASSERT(__item_ != nullptr); |
| return __item_; |
| } |
| |
| [[nodiscard]] _Item** operator->() const noexcept |
| { |
| STDEXEC_ASSERT(__item_ != nullptr); |
| return &__item_; |
| } |
| |
| iterator& operator++() noexcept |
| { |
| __predecessor_ = __item_; |
| if (__item_) |
| { |
| __item_ = __item_->*_Next; |
| } |
| return *this; |
| } |
| |
| iterator operator++(int) noexcept |
| { |
| iterator __result = *this; |
| ++*this; |
| return __result; |
| } |
| |
| friend bool operator==(const iterator&, |
| const iterator&) noexcept = default; |
| }; |
| |
| [[nodiscard]] iterator begin() const noexcept |
| { |
| return iterator(nullptr, __head_); |
| } |
| |
| [[nodiscard]] iterator end() const noexcept |
| { |
| return iterator(__tail_, nullptr); |
| } |
| |
| void splice(iterator pos, __intrusive_queue& other, iterator first, |
| iterator last) noexcept |
| { |
| if (first == last) |
| { |
| return; |
| } |
| STDEXEC_ASSERT(first.__item_ != nullptr); |
| STDEXEC_ASSERT(last.__predecessor_ != nullptr); |
| if (other.__head_ == first.__item_) |
| { |
| other.__head_ = last.__item_; |
| if (other.__head_ == nullptr) |
| { |
| other.__tail_ = nullptr; |
| } |
| } |
| else |
| { |
| STDEXEC_ASSERT(first.__predecessor_ != nullptr); |
| first.__predecessor_->*_Next = last.__item_; |
| last.__predecessor_->*_Next = pos.__item_; |
| } |
| if (empty()) |
| { |
| __head_ = first.__item_; |
| __tail_ = last.__predecessor_; |
| } |
| else |
| { |
| pos.__predecessor_->*_Next = first.__item_; |
| if (pos.__item_ == nullptr) |
| { |
| __tail_ = last.__predecessor_; |
| } |
| } |
| } |
| |
| _Item* front() const noexcept |
| { |
| return __head_; |
| } |
| |
| _Item* back() const noexcept |
| { |
| return __tail_; |
| } |
| |
| private: |
| _Item* __head_ = nullptr; |
| _Item* __tail_ = nullptr; |
| }; |
| } // namespace __queue |
| |
| using __queue::__intrusive_queue; |
| |
| } // namespace stdexec |