/* Time class declaration.
   Copyright (C) 2002-2004 Roberto Bagnara <bagnara@cs.unipr.it>

This file is part of the Parma Watchdog Library (PWL).

The PWL 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.

The PWL is distributed in the hope that it will be useful, but WITHOUT
ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
for more details.

You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307,
USA.

For the most up-to-date information see
http://www.cs.unipr.it/Software/ . */

#ifndef PWL_Time_defs_hh
#define PWL_Time_defs_hh 1

#include "Time.types.hh"

namespace Parma_Watchdog_Library {

//! Returns <CODE>true</CODE> if and only if \p x and \p y are equal.
bool operator==(const Time& x, const Time& y);

//! Returns <CODE>true</CODE> if and only if \p x and \p y are different.
bool operator!=(const Time& x, const Time& y);

//! Returns <CODE>true</CODE> if and only if \p x is shorter than \p y.
bool operator<(const Time& x, const Time& y);

//! \brief
//! Returns <CODE>true</CODE> if and only if \p x is shorter than
//! or equal to \p y.
bool operator<=(const Time& x, const Time& y);

//! Returns <CODE>true</CODE> if and only if \p x is longer than \p y.
bool operator>(const Time& x, const Time& y);

//! \brief
//! Returns <CODE>true</CODE> if and only if \p x is longer than
//! or equal to \p y.
bool operator>=(const Time& x, const Time& y);

//! Returns the sum of \p x and \p y.
Time operator+(const Time& x, const Time& y);

//! \brief
//! Returns the difference of \p x and \p y or the null interval,
//! if \p x is shorter than \p y.
Time operator-(const Time& x, const Time& y);

} // namespace Parma_Watchdog_Library

//! A class for representing and manipulating positive time intervals.
class Parma_Watchdog_Library::Time {
public:
  //! Zero seconds.
  Time();

  //! Constructor taking a number of hundredths of a second.
  explicit Time(unsigned long hundredths_of_a_second);

  //! Constructor with seconds and microseconds.
  Time(unsigned long s, unsigned long m);

  //! \brief
  //! Returns the number of whole seconds contained in the represented
  //! time interval.
  unsigned long seconds() const;

  //! \brief
  //! Returns the number of microseconds that, when added to the number
  //! of seconds returned by seconds(), give the represent time interval.
  unsigned long microseconds() const;

  //! Adds \p y to \p *this.
  Time& operator+=(const Time& y);

  //! \brief
  //! Subtracts \p y from \p *this; if \p *this is shorter than \p y,
  //! \p *this is set to the null interval,
  Time& operator-=(const Time& y);

  //! Checks if all the invariants are satisfied.
  bool OK() const;

private:
  //! Number of seconds.
  unsigned long secs;

  //! Number of microseconds.
  unsigned long microsecs;
};

#include "Time.inlines.hh"

#endif // !defined(PWL_Time_defs_hh)