/**
 * PANDA 3D SOFTWARE
 * Copyright (c) Carnegie Mellon University.  All rights reserved.
 *
 * All use of this software is subject to the terms of the revised BSD
 * license.  You should have received a copy of this license along
 * with this source code in a file named "LICENSE."
 *
 * @file circBuffer.h
 * @author drose
 * @date 1999-02-08
 */

#ifndef CIRCBUFFER_H
#define CIRCBUFFER_H

#include "pandabase.h"

/**
 * This class implements a queue of some type via a circular buffer.  The
 * circular buffer has the advantage that no synchronization is required when
 * one process adds to the queue while another process extracts.  It works for
 * any kind of Thing that has a valid assignment operator and copy constructor
 * defined.
 */
template<class Thing, int max_size>
class CircBuffer {
public:
  INLINE CircBuffer();
  INLINE ~CircBuffer();

  // Methods that are safe to call without synchronization primitives from
  // either thread.
  INLINE int size() const;

  // Methods that are safe to call without synchronization primitives only
  // from the reader thread.
  INLINE bool empty() const;

  INLINE const Thing &front() const;
  INLINE Thing &front();
  INLINE void pop_front();

  INLINE const Thing &operator[] (int n) const;
  INLINE Thing &operator[] (int n);

  // Methods that are safe to call without synchronization primitives only
  // from the writer thread.
  INLINE bool full() const;

  INLINE const Thing &back() const;
  INLINE Thing &back();
  INLINE void push_back(const Thing &t);

  INLINE void clear();

private:
  Thing _array[max_size+1];
  int _in, _out;
};

#include "circBuffer.I"

#endif