linkedlistiterext.h

用于词法分析的词法分析器

/*
  $Id: LinkedListIterExt.h,v 1.2 1997/02/02 01:31:04 matt Exp $

  Extended linked list iterator with insert/remove.
  
  (c) Apr 95 Matt Phillips.
  */

#ifndef _LLISTXI_H
#define _LLISTXI_H

#include "LinkedList.h"

// NOTE: this iterator can be used on any class derived from the
// LinkedList class, but ensure first that it does not cause itegrity
// violations.  Some alternative extended iterators exist for classes
// where this iterator is not appropriate.
 
template <class T, class E>
class LinkedListImpIterExt : public LinkedListImpIter<T, E>
{
public:
   
  LinkedListImpIterExt (LinkedListImp<T, E> &l) : 
    prev (0), LinkedListImpIter<T, E> (l) {}
   
  int hasPrev () const {return prev != 0;}
  T &refPrev () const
  {CHECK (prev, "null prev reference"); return prev->ref ();}

  virtual void reset () {LinkedListImpIter<T, E>::reset (); prev = 0;}
  virtual void operator ++ (int)
  {prev = i; LinkedListImpIter<T, E>::operator ++ (0);}

  // insert t before current item
  void insert (T &t)
  {
    ITER_CURRENT (prev);

    E *e = new E (t, i);

    if (prev)
    {
      prev->next = e;
      prev = e;
    } else
      setHead (e);


    incNItems ();
  }

  // remove current item (current item = next afterwards)
  void remove ();
   
protected:

  E *prev;
};

template <class T, class E>
void LinkedListImpIterExt<T, E>::remove ()
{
  ITER_CURRENT (i);		// check for valid iterator
  E *next = i->next;
   
  if (prev)
    prev->next = i->next;
  else
    setHead (i->next);
   
  delete i;

  i = next;
   
  decNItems ();
}

#define TypeDLinkedListIterExt(T)  LinkedListImpIterExt<T, DLinkedItem <T> >
#define TypeILinkedListIterExt(T)  LinkedListImpIterExt<T, ILinkedItem <T, 0> >
#define TypeIOLinkedListIterExt(T) LinkedListImpIterExt<T, ILinkedItem <T, 1> >

#endif