linkedlistwithtailiterext.h

用于词法分析的词法分析器

/*
  $Id: LinkedListWithTailIterExt.h,v 1.2 1997/02/02 01:31:05 matt Exp $

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

#ifndef _LLISTTXI_H
#define _LLISTTXI_H

#include "LinkedListWithTail.h"

// NOTE: this class cannot inherit from the LinkedListExtIter class
// because then it would not have access to the LinkedListWithTail
// class' tail member via the LinkedListWithTailIter class.

template <class T, class E>
class LinkedListWithTailImpIterExt : public LinkedListWithTailImpIter<T, E>
{
public:
   
  LinkedListWithTailImpIterExt (LinkedListWithTailImp<T, E> &l) : 
    prev (0), LinkedListWithTailImpIter<T, E> (l) {}
   
  int hasPrev () const {return prev != 0;}

  T &refPrev () const
  {
    CHECK (prev, "null prev reference");
    return prev->ref ();
  }

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

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

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

  E *prev;
};

template <class T, class E>
void LinkedListWithTailImpIterExt<T, E>::insert (T &t)
{
  ITER_CURRENT (prev);
   
  E *e = new E (t, i);
   
  if (prev)
  {
    prev->next = e;
    prev = e;
  } else
    setHead (e);
   
  incNItems ();
}

template <class T, class E>
void LinkedListWithTailImpIterExt<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 ();

  if (i->next == 0) setTail (prev);
}

#define TypeDLinkedListWithTailIterExt(T) LinkedListWithTailImpIterExt<T, DLinkedItem<T> >
#define TypeILinkedListWithTailIterExt(T) LinkedListWithTailImpIterExt<T, ILinkedItem<T, 0> >
#define TypeIOLinkedListWithTailIterExt(T) LinkedListWithTailImpIterExt<T, ILinkedItem<T, 1> >

#endif