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/*
* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice, this
* list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#pragma once
#include <AK/OwnPtr.h>
#include <AK/SinglyLinkedList.h>
#include <AK/Vector.h>
namespace AK {
template<typename T, int segment_size = 1000>
class Queue {
public:
Queue() { }
~Queue() { }
size_t size() const { return m_size; }
bool is_empty() const { return m_size == 0; }
void enqueue(T&& value)
{
if (m_segments.is_empty() || m_segments.last()->size() >= segment_size)
m_segments.append(make<Vector<T, segment_size>>());
m_segments.last()->append(move(value));
++m_size;
}
void enqueue(const T& value)
{
enqueue(T(value));
}
T dequeue()
{
ASSERT(!is_empty());
auto value = move((*m_segments.first())[m_index_into_first++]);
if (m_index_into_first == segment_size) {
m_segments.take_first();
m_index_into_first = 0;
}
--m_size;
return value;
}
const T& head() const
{
ASSERT(!is_empty());
return (*m_segments.first())[m_index_into_first];
}
void clear()
{
m_segments.clear();
m_index_into_first = 0;
m_size = 0;
}
private:
SinglyLinkedList<OwnPtr<Vector<T, segment_size>>> m_segments;
size_t m_index_into_first { 0 };
size_t m_size { 0 };
};
}
using AK::Queue;
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