///////    File: ArbList.h    ///////
#ifndef Arblist_SEEN__
#define Arblist_SEEN__
// linked list of arbitrary entries
#include <iostream.h>
typedef void *Arbent;

class ArbCell
{ friend class ArbList;
  private:
    Arbent item;
    ArbCell* next;
    ArbCell(Arbent c = NULL, ArbCell* ptr = NULL)
    :  item(c), next(ptr) { }   // constructor
};

typedef int (* EQ_FN)(Arbent, Arbent);  // equality tester
typedef void (* DISP_FN)(Arbent);       // item displayer


class ArbList
{   friend class ArbList_ac;
  public:
    ArbList()                  // empty list constructor 
    : head(NULL), equal(NULL), dispfn(NULL) { }
    ArbList(Arbent c, EQ_FN eq, DISP_FN d)// list with first cell
    : head (new ArbCell(c,NULL)), equal(eq), dispfn(d) { }
    ArbCell* first() const { return head; } // first cell
    static ArbCell* next(ArbCell* p)
    { return (p ? p->next : p); }                // next cell
    static int is_end(ArbCell* p)
    { return(p == NULL); }                  // end test

    ArbCell* last();                  // last cell
    ArbCell* find(Arbent c);            // first item equals c

    int substitute(Arbent r, Arbent s);    // r for first s on list
    int remove(Arbent c);                // c from entire list
    void remove(ArbCell* cell);       // remove given cell
    int shorten(int n);                // remove first n cells
    static Arbent content(ArbCell* p)
    {   return p->item;   }
    int put_on(Arbent c);                // insert in front
    int insert(Arbent c, ArbCell* cell);// insert after cell
    int append(Arbent c)                 // insert at end
    { return insert(c, last()); }
    int is_empty() { return is_end(head); }
    void display(ArbCell* p);         // display from p to end
    void display() { display(head); }  // display whole list
    ~ArbList();                           // destructor
  private:
    ArbCell* head;                    // first cell of list
    void free();                    // free all cells
    EQ_FN equal;
    DISP_FN dispfn;
};
#endif