/* File: sl_list.H      Copyright glh 9/15/92 */
#ifndef SLISTH
#define SLISTH
#include <stdlib.h>
#include <iostream.h>
#include <assert.h>

typedef enum {false, true} Boolean;

// forward references for template classes
template <class Type> class SlList;
template <class Type> class SlListIterator;

template<class T>
class SlNode {
  friend class SlList<T>;
  friend class SlListIterator<T>;
  friend ostream& operator<<(ostream&, const SlList<T>&);
  private:
    T data;
    SlNode<T>* next;
    SlNode() {} 
    inline SlNode(const T&);
};

template<class T>
inline SlNode<T>::SlNode(const T& elm) {data = elm;}

template<class T>
class SlList {
  friend class SlListIterator<T>;
  protected:
    int length;
    SlNode<T>* tail; // tail->next is the head of the list
  public:
    inline SlList();
    SlList(const T&);
    SlList(const SlList<T>&);
    inline ~SlList();
    SlList<T>& operator=(const SlList<T>&);
    friend ostream& operator<<(ostream&, const SlList<T>&);
    void Insert(const T&, int);
    void Append(const T&);
    T& Retrieve(int) const;
    void Delete(int);
    inline int Length() const;
    inline Boolean Empty() const;
    void MakeEmpty();
};

template<class T>
inline SlList<T>::SlList() {length=0; tail=NULL;}

template<class T>
inline SlList<T>::~SlList() {MakeEmpty();}

template<class T>
inline int SlList<T>::Length() const {return length;}

template<class T>
inline Boolean SlList<T>::Empty() const {return length == 0 ? true : false;}

template<class T>
class SlListIterator {
  private:
    int current;
    const SlList<T>* list;
  public:
    SlListIterator() {}
    SlListIterator(const SlList<T>* lst);
    int Reset();
    inline int Current() const;
    int operator++(); //prefix
    int operator++(int); //postfix
};

template<class T>
inline int SlListIterator<T>::Current() const {return current;}

#endif