ladybird/AK/Queue.h
Andreas Kling c699d9d79d AK: Add a simple Queue<T> class.
The underlying data structure is a singly-linked list of Vector<T>.
We never shift any of the vector contents around, but we batch the memory
allocations into 1000-element segments.
2019-06-15 10:35:35 +02:00

50 lines
1.0 KiB
C++

#pragma once
#include <AK/OwnPtr.h>
#include <AK/SinglyLinkedList.h>
#include <AK/Vector.h>
namespace AK {
template<typename T>
class Queue {
public:
Queue() { }
~Queue() { }
int 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;
}
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;
}
private:
static const int segment_size = 1000;
SinglyLinkedList<OwnPtr<Vector<T, segment_size>>> m_segments;
int m_index_into_first { 0 };
int m_size { 0 };
};
}
using AK::Queue;