// --------------------------------------------------------------------------
// Linear Containers
// A. Fischer June 12, 2001                                  file: linear.hpp
// --------------------------------------------------------------------------
#pragma once

#include <iostream>
#include "container.hpp"
#include "cell.hpp"
#include "item.hpp"
using namespace std;

template <class T>
class Linear: public Container<T> {
  protected: // -------------------------------------------------------------
    Cell<T>* head;       // This is a dummy header for the list.

  private:   // -------------------------------------------------------------
    Cell<T>* here;       // Cursor for traversing the container.
    Cell<T>* prior;      // Trailing pointer for traversing the container.

  protected: // -------------------------------------------------------------
            Linear(): head(new Cell<T>), here( NULL ), prior( head ) {}
    virtual ~Linear ();
            void  reset()           { prior = head; here = head->next; }
            bool  end() const       { return here == NULL; }
            void  operator ++();
    virtual void  insert( Cell<T>* cp );
    virtual void  focus() = 0;
            Cell<T>* remove();
            void  setPrior(Cell<T>* cp){ prior = cp; here = prior->next; }
            operator T*() const { return *here; }   // Cast Linear to T*. ------------
            // Delegate to fetch cell contents
            const T* getData( Cell<T>* cp ) const { return cp->data; }

  public:   // --------------------------------------------------------------
            void     put(T * ep)    { if (ep) insert( new Cell<T>(ep) ); }
            T*    pop();
            T*    peek()        { focus(); return *here; }
    virtual ostream& print( ostream& out );
};

template <class T>
inline ostream& operator<<(ostream& out, Linear<T>& s) {return s.print(out); }