2020-01-18 11:38:21 +03:00
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/*
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* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are met:
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*
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* 1. Redistributions of source code must retain the above copyright notice, this
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* list of conditions and the following disclaimer.
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*
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* 2. Redistributions in binary form must reproduce the above copyright notice,
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* this list of conditions and the following disclaimer in the documentation
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* and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
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* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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2018-10-22 23:46:02 +03:00
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#pragma once
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2019-04-14 05:33:43 +03:00
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#include <AK/Assertions.h>
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#include <AK/Types.h>
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2018-10-22 23:46:02 +03:00
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namespace AK {
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2019-02-26 04:17:25 +03:00
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template<typename T, int Capacity>
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2018-10-22 23:46:02 +03:00
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class CircularQueue {
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public:
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CircularQueue()
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{
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2019-10-23 13:20:45 +03:00
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}
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~CircularQueue()
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{
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clear();
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2018-10-22 23:46:02 +03:00
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}
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2019-04-20 04:47:35 +03:00
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void clear()
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{
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2019-10-23 13:20:45 +03:00
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for (int i = 0; i < m_size; ++i)
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elements()[(m_head + i) % Capacity].~T();
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2019-04-20 04:47:35 +03:00
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m_head = 0;
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m_size = 0;
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}
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2018-12-03 02:39:25 +03:00
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bool is_empty() const { return !m_size; }
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2019-02-26 04:17:25 +03:00
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int size() const { return m_size; }
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2018-10-22 23:46:02 +03:00
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2019-02-26 04:17:25 +03:00
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int capacity() const { return Capacity; }
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2018-11-12 03:28:46 +03:00
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2019-10-23 13:20:45 +03:00
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void enqueue(T&& value)
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2018-10-22 23:46:02 +03:00
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{
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2019-10-23 13:20:45 +03:00
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auto& slot = elements()[(m_head + m_size) % Capacity];
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if (m_size == Capacity)
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slot.~T();
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new (&slot) T(value);
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2018-11-12 03:28:46 +03:00
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if (m_size == Capacity)
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m_head = (m_head + 1) % Capacity;
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2018-10-22 23:46:02 +03:00
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else
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++m_size;
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}
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2019-10-23 13:20:45 +03:00
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void enqueue(const T& value)
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{
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enqueue(T(value));
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}
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2018-10-22 23:46:02 +03:00
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T dequeue()
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{
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2018-12-03 02:39:25 +03:00
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ASSERT(!is_empty());
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2019-10-23 13:20:45 +03:00
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auto& slot = elements()[m_head];
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T value = move(slot);
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slot.~T();
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2018-11-12 03:28:46 +03:00
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m_head = (m_head + 1) % Capacity;
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2018-10-22 23:46:02 +03:00
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--m_size;
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return value;
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}
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2019-10-23 13:20:45 +03:00
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const T& at(int index) const { return elements()[(m_head + index) % Capacity]; }
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2019-03-15 14:13:51 +03:00
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2019-04-20 04:44:01 +03:00
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const T& first() const { return at(0); }
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const T& last() const { return at(size() - 1); }
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2019-01-29 00:40:55 +03:00
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class ConstIterator {
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public:
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bool operator!=(const ConstIterator& other) { return m_index != other.m_index; }
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ConstIterator& operator++()
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{
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m_index = (m_index + 1) % Capacity;
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if (m_index == m_queue.m_head)
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m_index = m_queue.m_size;
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return *this;
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}
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2019-10-23 13:20:45 +03:00
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const T& operator*() const { return m_queue.elements()[m_index]; }
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2019-05-28 12:53:16 +03:00
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2019-01-29 00:40:55 +03:00
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private:
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friend class CircularQueue;
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2019-05-28 12:53:16 +03:00
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ConstIterator(const CircularQueue& queue, const int index)
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: m_queue(queue)
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, m_index(index)
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{
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}
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2019-01-29 00:40:55 +03:00
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const CircularQueue& m_queue;
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2019-02-26 04:17:25 +03:00
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int m_index { 0 };
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2019-01-29 00:40:55 +03:00
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};
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ConstIterator begin() const { return ConstIterator(*this, m_head); }
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ConstIterator end() const { return ConstIterator(*this, size()); }
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2019-03-27 16:56:35 +03:00
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int head_index() const { return m_head; }
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2019-10-16 15:29:06 +03:00
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protected:
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2019-10-23 13:20:45 +03:00
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T* elements() { return reinterpret_cast<T*>(m_storage); }
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const T* elements() const { return reinterpret_cast<const T*>(m_storage); }
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2019-01-29 00:40:55 +03:00
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friend class ConstIterator;
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2019-10-23 13:20:45 +03:00
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alignas(T) u8 m_storage[sizeof(T) * Capacity];
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2019-02-26 04:17:25 +03:00
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int m_size { 0 };
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int m_head { 0 };
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2018-10-22 23:46:02 +03:00
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};
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}
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using AK::CircularQueue;
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