// revised_vector.h: based on simple_vector, but with const
// based on Stroustrup, A Tour of C++ (2014), p. 37

#ifndef _REVISED_VECTOR_H
#define _REVISED_VECTOR_H

#include <stdexcept>

class AbstractContainer {
public:
  virtual ~AbstractContainer() { }
  virtual int size() const = 0;
  virtual double& operator[](int index) = 0;
  virtual const double& operator[](int index) const = 0;
};  

class FixedVector : public AbstractContainer {
public:
  FixedVector(int size) : elements{new double[size]}, _size{size}
  {
    for(int i = 0; i < size; ++i)
      elements[i] = 0.0;
  }
   
 ~FixedVector() {
    delete [] elements;
  }

  int size() const override { return _size; }

  double& operator[](int index) override {
    if ( index < 0 || index >= _size )
      throw std::out_of_range("Illegal index into vector.");
    return elements[index];
  }

  // this version called in const context
  const double& operator[](int index) const override {
    if ( index < 0 || index >= _size )
      throw std::out_of_range("Illegal index into vector.");
    return elements[index];
  }

private:
  int _size;                   // debugging trick: put first for visibility
  double *elements;
};

#endif