/******************************************************************
 * Memorial University of Newfoundland
 * Engineering 4892 Data Structures
 *
 * $RCSfile$   $Revision$
 * $Date$
 * $State$ 
 *
 * Include file for Assignment 2.
 *
 ******************************************************************/

/******************************************************************
 *                     REVISION HISTORY
 *
 * $Log$
 *
 ******************************************************************/

#ifndef BIGNAT_DEF
#define BIGNAT_DEF

#include <string>

class BigNat {
  // A class for representing arbitrarily large natural numbers.
  // Representation: 
  //    D a sequence of digits
  public:
  // Types
    enum Status { Ok, PreFail, NewFail };

  // Constructors
    BigNat(int n = 0);
    // Default constructor. 
    // Pre: n >= 0
    // Post: n = 0 -> D = _ /\ n != 0 -> D = digits of n, least significant
    //                                                    first.

    BigNat(const BigNat& r);
    // Copy constructor

  // Destructor
    ~BigNat();

  // Accessors
    std::string toString() const;
    // Post: Result = digits of D in 'traditional' order (i.e., most
    //                                            significant first.)
    
    Status getStatus() const { return err; }

  // Mutators
    BigNat& operator =(const BigNat& r);
    // Assignment operator

    BigNat& operator += (const BigNat& r);
    // Post: D' = D + r /\ Result = D'

    BigNat& operator += (int r);
    // Pre: r > 0
    // Post: D' = D + r /\ Result = D'

    BigNat& operator *= (int r);
    // Pre: 0 < r < 10
    // Post: D' = D * r /\ Result = D'

  private:
  // Representation: 
  //   *head is least significant digit, *(head->next) is next least
  //   significant etc.
  //   Empty list means 0.

    struct Node {
      int digit;
      Node* next;
    };

    Node *head;
    Status err;

};

#endif