// Prog: tribool_class_template.cpp
// Author: ...
// implements three-valued logic as a class

#include<iostream>

class Tribool {
// ... (private: or public: , which one?)
  // POST: *this is initialized with value 'unknown'
  // ... (default-constructor)
  
  // POST: *this is initialized as true (if b == 1),
  //       as false (if b == 0) or as unknown (else)
  // ... (constructor for int --> Tribool)
  
  // POST: *this is initialized as true if b is true, or as
  //       false if b is false
  // Note: this constructor is not necessarily needed if the
  //       constructor for int --> Tribool is suitably implemented
  //       and the internal representation of the three-valued logic
  //       is suitably chosen.
  // ... (constructor for bool --> Tribool)
  
  // POST: returns true iff value_ is boolean (either true or false)
  // ... (is_bool)
  
  // POST: returns *this AND y
  // ... (a helper function which executes x AND y (for x of type Tribool))
  //     (Note: you don't have to implement this member if you see
  //     other ways to implement operator&& such that it works when it is
  //     called with two arguments of type Tribool as well as with one
  //     argument of type bool and the other of type Tribool.)
  
  // POST: returns *this OR y
  // ... (a helper function which executes x OR y (for x of type Tribool))
  //     (Note: you don't have to implement this member if you see
  //     other ways to implement operator|| such that it works when it is
  //     called with two arguments of type Tribool as well as with one
  //     argument of type bool and the other of type Tribool.)
  
  // POST: writes the value of *this to o
  // ... (print-function; needed for operator<< to access value)
  
  
// ... (private: or public: , which one?)
  // ... (represent the value here)
};



// POST: returns x AND y
// ... (operator&&)

// POST: returns x OR y
// ... (operator||)

// POST: Tribool value is written to o
// ... (operator<<)



int main() {
  // print 3 x 3 truth table for AND
  const Tribool t = 1, f = 0, u = 800; // true, false, and unknown
  std::cout << (f && f) << " " << (f && u) << " " << (f && t) << "\n"
            << (u && f) << " " << (u && u) << " " << (u && t) << "\n"
            << (t && f) << " " << (t && u) << " " << (t && t) << "\n\n";

  // print 3 x 3 truth table for OR
  std::cout << (f || f) << " " << (f || u) << " " << (f || t) << "\n"
            << (u || f) << " " << (u || u) << " " << (u || t) << "\n"
            << (t || f) << " " << (t || u) << " " << (t || t) << "\n\n";
 
  // the operators also work for bools:
  const bool b = true;
  std::cout << (b || u) << " " << (u && b) << "\n";
  std::cout << (b || f) << " " << (f && b) << "\n";
  
  return 0;
}