/*
  rational.hh -- declare rational helpers

  source file of the Flower Library

  (c)  1997--2003 Han-Wen Nienhuys <hanwen@cs.uu.nl>
*/


#ifndef RATIONAL_HH
#define RATIONAL_HH

#include "compare.hh"
#include "arithmetic-operator.hh"
#include "flower-proto.hh"
#include "string.hh"


/**
   Rational numbers.  Included is support for + and - infinity.
 */
class Rational {
  /**
     Sign of rational.
     -2, .. 2

     -2,2 is - and + infinity.
     -1,1 is negative and positive.
     0 if *this is zero.
   */
  int sign_;
  unsigned int num_, den_;
  void normalise ();
  void copy (Rational const &);

public:
  void set_infinite (int sign);
  bool infty_b () const
    {
      return sign_ == 2 || sign_ == -2;
    }
  void invert ();
  int num () const { return sign_ * num_; }
  int den () const { return den_; }

  Rational trunc_rat () const;
  Rational div_rat (Rational) const;
  Rational mod_rat (Rational) const;
  void negate ();
  //   operator bool () const;
  int to_int () const;
  operator double () const;
  Rational operator - () const;
  /**
     Initialize to 0. 
   */
  Rational ();
  Rational (int);
  Rational (int, int);
  Rational (double);
  Rational (Rational const&r) {   copy (r);}
  Rational &operator = (Rational const &r) {
    copy (r); return *this;
  }

  Rational &operator *= (Rational);
  Rational &operator /= (Rational);  
  Rational &operator += (Rational);
  Rational &operator -= (Rational);
  Rational &operator %= (Rational);
  static int compare (Rational const&, Rational const&);
  int sign () const;
  String to_string () const;
};

IMPLEMENT_ARITHMETIC_OPERATOR (Rational, / );
IMPLEMENT_ARITHMETIC_OPERATOR (Rational, + );
IMPLEMENT_ARITHMETIC_OPERATOR (Rational, * );
IMPLEMENT_ARITHMETIC_OPERATOR (Rational, - );
IMPLEMENT_ARITHMETIC_OPERATOR (Rational, % );

INSTANTIATE_COMPARE (Rational const&, Rational::compare);

int compare (Rational const&,Rational const&);
int sign (Rational r);

inline void
Rational::copy (Rational const&r)
{
  sign_ = r.sign_;
  num_ = r.num_;
  den_ = r.den_;
}

#if 0
ostream &
operator << (ostream &,  Rational);
#endif

const Rational infinity_rat = INT_MAX;

#endif // RATIONAL_HH
