//
// This is example code from Chapter 17.10 "The this pointer" of
// "Programming -- Principles and Practice Using C++" by Bjarne Stroustrup
//

#include "std_lib_facilities.h"

//------------------------------------------------------------------------------

class Link {
public:
   string value; 

   Link(const string& v, Link* p = 0, Link* s = 0)
      : value{v}, prev{p}, succ{s} { }

   Link* insert(Link* n) ;   // insert n before this object
   Link* add(Link* n) ;      // insert n after this object
   Link* erase() ;           // remove this object from list
   Link* find(const string& s);    // find s in list
   const Link* find(const string& s) const; // find s in list

   Link* advance(int n) const;     // move n positions in list

   Link* next() const { return succ; }
   Link* previous() const { return prev; }
private:
   Link* prev;
   Link* succ;
};

//------------------------------------------------------------------------------

Link* Link::insert(Link* n)   // insert n before p; return n
{
   Link* p = this;           // pointer to this object
   if (n==0) return p;       // nothing to insert
   if (p==0) return n;       // nothing to insert into
   n->succ = p;              // p comes after n
   if (p->prev) p->prev->succ = n;
   n->prev = p->prev;        // p's predecessor becomes n's predecessor
   p->prev = n;              // n becomes p's predecessor
   return n;
}

//------------------------------------------------------------------------------