#ifndef _POSITION1_H
#define _POSITION1_H

/**
  * A Position represents a (row,column) in a grid
  * whose (0,0) is upper-left as in matrix coordinates.
  *
  * Once constructed, a position doesn't change
  * (all member functions are const), although
  * a Position can be assigned to an existing Position.
  * For example,
  *
  *    Position p(2,3);
  *    Position q;        // default  (-1,-1)
  *    q = p;             // q now at (2,3)
  *
  * Adjacent Positions of a given Position can be
  * determined as illustrated:
  *
  *    Position p(5,5);
  *    Position q;
  *
  *    q = p.North();    // q is (4,5)
  *    q = p.South();    // q is (6,5)
  *    q = p.East();     // q is (5,6)
  *    q = p.West();     // q is (5,4)
  *
  */

#include <iostream.h>
#include "apstring.h"

class Position
{
  public:

    // constructors

    Position();
    Position(int r, int c);

    // Accessor functions

    int Row() const;
    int Col() const;  

    Position North() const;
    Position South() const;
    Position East() const;
    Position West() const;
    bool Equals(const Position & rhs) const;
    apstring ToString() const;  
    
    // Mutator fucntions    
    void Input(istream & in);

  private:
    int myRow;
    int myCol;
};


//	Free fucntions

ostream & operator << (ostream & out, const Position & pos);
  // postcondition: pos inserted onto stream out

istream & operator >> (istream & in, Position & pos);
  // postcondition: Position value is read from in input stream

bool operator == (const Position & lhs, const Position & rhs);
  // postcondition: returns true iff lhs == rhs

bool operator < (const Position & lhs, const Position & rhs);
  // postcondition: returns true iff lhs < rhs


/*

Position()
// post: Row() == -1, Col() == -1
  
Position(int r, int c)
// post: Row() == r, Col() == c

int Row() const
// post: returns row of Position
  
int Col() const
// post: returns column of Position

Position North() const
// post: returns Position north of (up from) *this position

Position South() const
// post: returns Position south of (down from) *this position

Position East() const
// post: returns Position east (right) of *this position

Position West() const
// post: returns Position west (left) of *this position

bool Equals(const Position & rhs) const
// post: returns true iff *this position equals rhs

apstring ToString() const
// post: returns stringized form of Position [e.g. "(2, 3)"]
  
void Input(istream & in)
// pre: in is open
// post: extracts from "in" and places values in *this

ostream & operator << (ostream & out, const Position & pos)
// pre: out is open
// post: pos inserted onto stream out

istream & operator >> (istream & in, Position & pos)
// post: Position value is read from in input stream

bool operator == (const Position & lhs, const Position & rhs)
// post: returns true iff lhs == rhs

bool operator < (const Position & lhs, const Position & rhs)
// post: returns true iff lhs < rhs


*/

#endif