#ifndef __TLIST_H
#define __TLIST_H
// tlist.h
// this is a base template class for lists
// it is for a list of elements. An element can be of any class, but it must
// have the operators == and = defined, so that the list can be searched
// also the operator >> must be defined for write

template <class Elem> class List {
  public:
    virtual Elem *Insert(const Elem &elem) {return NULL;}
    // insert elem into the list
    // returns a ptr to elem if elem inserted, NULL if elem was already there
    // i.e. doesn't put in duplicates and returns NULL for duplicates
    virtual Elem *Search(const Elem &elem) {return NULL;}
    // finds the element that matchs elem and returns it. This allows assoc
    // retrieval
    // returns NULL if the elem is not found
    virtual void Write(ostream &s) {;}
    // writes out the list of elements. Requires that the element overload the
    // stream output operator
    virtual int Empty(void) {return 0;}
    // returns true if the list is empty
};

#endif