pmlpp/sfw/core/queue.h

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#ifndef QUEUE_H
#define QUEUE_H
#include "core/error_macros.h"
#include "vector.h"
template<class T>
class Queue
{
public:
void enqueue(const T &job);
T dequeue();
const T &peek() const;
bool is_empty() const;
bool is_full() const;
int size() const;
int capacity() const;
void ensure_capacity(const int capacity);
void resize(const int s);
void pack();
Queue();
Queue(int prealloc);
Queue(int prealloc, int grow_by);
~Queue();
private:
T* _data;
int _head;
int _tail;
int _capacity;
int _grow_size;
};
template <class T>
void Queue<T>::pack()
{
if (_head == _tail)
{
_head = 0;
_tail = 0;
return;
}
if (_head == 0 && _tail == _capacity)
{
resize(_capacity + _grow_size);
return;
}
int j = 0;
for (int i = _head; i < _tail; ++i)
{
_data[j++] = _data[i];
}
_head = 0;
_tail = j;
}
template <class T>
void Queue<T>::enqueue(const T &job)
{
if (_tail == _capacity)
{
pack();
}
_data[_tail++] = job;
}
template <class T>
T Queue<T>::dequeue()
{
CRASH_COND(is_empty());
return _data[_head++];
}
template <class T>
const T &Queue<T>::peek() const
{
CRASH_COND(is_empty());
return _data[_head];
}
template <class T>
bool Queue<T>::is_empty() const
{
return _head == _tail;
}
template <class T>
bool Queue<T>::is_full() const
{
return (_head == 0) && (_tail == _capacity);
}
template <class T>
int Queue<T>::size() const
{
return _tail - _head;
}
template <class T>
int Queue<T>::capacity() const
{
return _capacity;
}
template <class T>
void Queue<T>::ensure_capacity(const int capacity)
{
if (_capacity < capacity)
{
resize(capacity);
}
}
template <class T>
void Queue<T>::resize(const int s)
{
if (s == 0 && _data)
{
delete[] _data;
_data = nullptr;
_capacity = s;
return;
}
if (!_data)
{
_data = new T[s];
_capacity = s;
return;
}
if (is_empty())
{
delete[] _data;
_data = new T[s];
_capacity = s;
return;
}
if (!is_full())
{
pack();
}
T* nd = new T[s];
int to = s > _tail ? _tail : s;
for (int i = 0; i < to; ++i)
{
nd[i] = _data[i];
}
delete[] _data;
_data = nd;
_capacity = s;
}
template <class T>
Queue<T>::Queue()
{
_data = nullptr;
_head = 0;
_tail = 0;
_capacity = 20;
_grow_size = 10;
resize(_capacity);
}
template <class T>
Queue<T>::Queue(int prealloc)
{
_data = nullptr;
_head = 0;
_tail = 0;
_capacity = prealloc;
_grow_size = 10;
resize(_capacity);
}
template <class T>
Queue<T>::Queue(int prealloc, int grow_by)
{
_data = nullptr;
_head = 0;
_tail = 0;
_capacity = prealloc;
_grow_size = grow_by;
resize(_capacity);
}
template <class T>
Queue<T>::~Queue()
{
if (_data)
{
delete[] _data;
_data = nullptr;
}
}
#endif