/***************************************************************************
                          primenumber.h  -  class primenumber
                             -------------------
    begin                : Tue Nov 27 16:40:42 CET 2001
    copyright            : (C) 2001 by Sebastian Stein
    email                : seb.kde@hpfsc.de
 ***************************************************************************/

/***************************************************************************
 *                                                                         *
 *   This program is free software; you can redistribute it and/or modify  *
 *   it under the terms of the GNU General Public License as published by  *
 *   the Free Software Foundation; either version 2 of the License, or     *
 *   (at your option) any later version.                                   *
 *                                                                         *
 ***************************************************************************/

#ifndef PRIMENUMBER_H
#define PRIMENUMBER_H

#include <qvector.h>

typedef QVector<uint> UnsignedIntArray;

/** Class to handle prime numbers.
 *  The prime numbers are stored in a static vector, so that different instances
 *  can use them. Each time a higher prime number is needed, the new found prime
 *  number is stored in the vector. To check if a given number is a prime number
 *  this vector is scanned and if needed new prime numbers are generated. This
 *  algorithm should reduce calculation time and speed up every program using
 *  this prime number class.
 *  \author Sebastian Stein */
class primenumber
{
public:
	/** constructor */
	primenumber();

	/** destructor */
	~primenumber();

	/** returns whether the given number is a prime number */
	short isPrimeNumber(uint number);

	/** returns the next prime number */
	unsigned int get_next();

	/** returns the first prime number */
	unsigned int get_first() const;

	/** return the last known prime number */
	unsigned int get_last() const;

	/** returns the current prime number */
	unsigned int get_current() const;

	/** moves the internal pointer to the first prime number */
	void move_first();

	/** moves the internal pointer to the last prime number */
	void move_last();

	/** moves the internal pointer to the next prime number */
	void move_forward();

	/** moves the internal pointer to the previous prime number */
	void move_back();

	/** Displays all known prime numbers, mainly used for debugging. */
	void display_all();
private:
	/** a vector storing all known prime numbers, access for all objects;
	 * we are using the vector<T> template; so we do not have to think
	 * about dynamic mem manipulation */
	static UnsignedIntArray prim_vector;

	/** current selected prime number */
	UnsignedIntArray::iterator current_pos;

	/** finds next prime number and adds it to the vector */
	void find_next();
};
#endif
