//----------------------------------------------------------------
//
// coloredTriangle.cpp
//
// Implements some classes to do with geometrical shapes, making use
// of the point example from Pohl, C++ by Dissection, pages 166-169.
//
// The code illustrates composition of classes and the derivation of one
// class from another.
//
// written by: Simon Parsons
// modified  : 24th February 2010
//
//----------------------------------------------------------------

#include <iostream>
using namespace std;

//----------------------------------------------------------------
//
// point

// The class point represents a location in a set of cartesian coordinates.
//
// It has two data members, an x and a y value, and three constructors.
// The constructors initialise the data members.
 
class point {

private:
  double x, y;

public:

  point() : x(0), y(0) { }	     // Default constructor
  point(double);                     // Convert double to point
  point(double, double);             // Initialise both x and y if we are
                                     // given values for them.

  void print() const;
  void set( double u, double v );
  double getX();
  double getY();

}; 

// Constructors

inline point::point(double u){       // Illustrates the use of "inline"
  x = u;
  y = 0;
}

point::point(double x, double y){    // Shows one use of "this"
  this->x = x;
  this->y = y;
}

// Print the values 

void point::print() const {
  cout << "(" << x << "," << y << ")\n";
}
 
// Set the values.

void point::set( double u, double v ) {
  x = u;
  y = v;
}

// Accessor functions. We need these to get hold of x and y since they
// are private.

double point::getX(){
  return x;
}

double point::getY(){
  return y;
}

// End of point

//----------------------------------------------------------------
//
// triangle

// The class triangle is made up of three points.
//
// The class demonstrates *composition* since it contains three point
// objects.
 
class triangle {

private:
  point a, b, c;

public:

  triangle(){};

  triangle(point, point, point);     // Initialise a, b and c if we are
                                     // given values for them.

  void print() const;
  void set( point, point, point);    // Set the values of the three points
  point getA();                      // and retrieve them also.
  point getB();
  point getC();

}; 

// Constructor

triangle::triangle(point p, point q, point r){
  a.set(p.getX(), p.getY());
  b.set(q.getX(), q.getY());
  c.set(r.getX(), r.getY());
}

// Function definitions

void triangle::print() const{
  cout << "The triangle has the following points:" << endl;
  a.print();
  b.print();
  c.print();
}

void triangle::set(point p, point q, point r){
  a.set(p.getX(), p.getY());
  b.set(q.getX(), q.getY());
  c.set(r.getX(), r.getY());
}

point triangle::getA(){
  return a;
}

point triangle::getB(){
  return b;
}

point triangle::getC(){
  return c;
}

// End of triangle

//----------------------------------------------------------------
//
// coloredTriangle
//
// A sub-class of triangle. 
//
// The classe demonstrates *derivation* since coloredTriangle is 
// derived from triangle.
//
// This is just a sketch of the class, A full implementation would
// need access functions for color also.

class coloredTriangle: public triangle {

private:
  
  string color;

public:

  coloredTriangle(point, point, point); // Initialise points if we are
                                        // given values for them.

}; 

// Constructor
//
// Note that because coloredTriangle is a triangle, we can call the public
// member functions of triangle. Here we use these to set the points.
coloredTriangle::coloredTriangle(point p, point q, point r){
  set(p, q, r);
  // However, we can't access the private data members of triangle. If you try:
  //a.set(p.getX(), p.getY());
  //b.set(q.getX(), q.getY());
  //c.set(r.getX(), r.getY());
  // then the compiler will flag up an error --- try it
}


// End of coloredTriamngle


//----------------------------------------------------------------
//
// Main program

// This creates three instances of point, creating them in different ways, and
// then printing out their contents.

int main() {
  point a;
  point b(2.2);
  point c(2.3, 4.5);

  a.set(1.2, 3.4);
  cout << "point a = ";
  a.print();
  cout << "point b = ";
  b.print();
  cout << "point c = ";
  c.print();

  cout << endl;
  triangle t(a, b, c);
  t.print();

  cout << endl;
  coloredTriangle e(a, b, c);
  e.print();
} 

// end of main()