// -*- coding: utf-8 -*-
// Time-stamp: <array2d.hpp   3 nov 2016 10:07:36>

// Abstract class for 2d arrays
// Two derived classes provide implementation.

#ifndef ARRAY2D_H
#define ARRAY2D_H

#include "iterator.hpp"

class Iterator;

// Abstract class
class Array2d {
public:
  // Constructors
  // Defaut constructor : no allocation
  Array2d() : nlin(0), ncol(0) {};
  // Constructor from dimensions
  Array2d(int m, int n) : nlin(m), ncol(n) {}
  // Copy constructor
  Array2d(const Array2d& a) : nlin(a.nlin), ncol(a.ncol) {}
  // Assignment operator
  Array2d& operator=(const Array2d& a);
  // Destructor
  virtual ~Array2d() {}
  // Returns numbers of lines and columns
  int ldim() const { return nlin; }
  int cdim() const { return ncol; }
  // Iterators
  Iterator begin();
  Iterator end();
  // Return an object of a non-abstract derived class
  static Array2d* make(int m, int n, int hint = 0);
  // Object Line contains everything to access an element of a line.
  // It contains a pointer to the beginning of the line and its length.
  class Line {
  public:
    // Constructor
    Line(double* q, int n) : p(q), ncol(n) {}
    // Access operators
    double& operator[](int j);
    const double& operator[](int j) const;
  private:
    double* p;			// Pointer to the beginning of the line
    int ncol;			// Number of columns
  };
  // Access operator
  // Each of this operator return an object of the internal class Line
  // This object of class line has also an operator[](int) which returns
  // a reference to the element of the given line.
  // Therefore, if a is an object of the class Array2d
  // a[i][j] returns a reference of the value indexed by the pair (i,j)
  // The evaluation of a[i] return an object l of class Line which 
  // contains a pointer to the beginning of the line and its length.
  // Then the expression l[j] returns the reference to the element.
  // Accessor for non-const objects
  virtual Line operator[](int i) = 0;
  // Accessor for const objects
  virtual const Line operator[](int i) const = 0;
protected:
  // Allocation of the array
  virtual void alloc() = 0;
  // Free the array
  virtual void free() = 0;
  int nlin;			// Number of lines
  int ncol;			// Number of columns
};

#endif