// This may look like C code, but it is really -*- C++ -*-
/* 
Copyright (C) 1988 Free Software Foundation
    written by Doug Lea (dl@rocky.oswego.edu)

This file is part of GNU CC.

GNU CC is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY.  No author or distributor
accepts responsibility to anyone for the consequences of using it
or for whether it serves any particular purpose or works at all,
unless he says so in writing.  Refer to the GNU CC General Public
License for full details.

Everyone is granted permission to copy, modify and redistribute
GNU CC, but only under the conditions described in the
GNU CC General Public License.   A copy of this license is
supposed to have been given to you along with GNU CC so you
can know your rights and responsibilities.  It should be in a
file named COPYING.  Among other things, the copyright notice
and this notice must be preserved on all copies.  
*/


#ifndef _<T>DLList_h
#pragma once
#define _<T>DLList_h 1

#include <Pix.h>
#include "<T>.defs.h"

#ifndef _<T>DLListNode_h
#define _<T>DLListNode_h 1

struct <T>DLListNode
{
  <T>DLListNode*         bk;
  <T>DLListNode*         fd;
  <T>                    hd;
                         <T>DLListNode();
                         <T>DLListNode(<T&> h, 
                                       <T>DLListNode* p = 0,
                                       <T>DLListNode* n = 0);
                         ~<T>DLListNode();
};

inline <T>DLListNode::<T>DLListNode() {}

inline <T>DLListNode::<T>DLListNode(<T&> h, <T>DLListNode* p = 0,
                                    <T>DLListNode* n = 0)
{
  hd = h;
  bk = p;
  fd = n;
}

inline <T>DLListNode::~<T>DLListNode() {}

typedef <T>DLListNode* <T>DLListNodePtr;

#endif

class <T>DLList
{
  friend class          <T>DLListTrav;

  <T>DLListNode*        h;

public:
                        <T>DLList();
                        <T>DLList(<T>DLList& a);
                        ~<T>DLList();

  <T>DLList&            operator = (<T>DLList& a);

  int                   empty();
  int                   length();

  void                  clear();

  Pix                   prepend(<T&> item);
  Pix                   append(<T&> item);
  void                  join(<T>DLList&);

  <T>&                  front();
  <T>                   remove_front();
  void                  del_front();

  <T>&                  rear();
  <T>                   remove_rear();
  void                  del_rear();

  <T>&                  operator () (Pix p);
  Pix                   first();
  Pix                   last();
  void                  next(Pix& p);
  void                  prev(Pix& p);
  int                   owns(Pix p);
  Pix                   ins_after(Pix p, <T&> item);
  Pix                   ins_before(Pix p, <T&> item);
  void                  del(Pix& p, int dir = 1);

  void                  error(const char* msg);
  int                   OK();
};


inline <T>DLList::~<T>DLList()
{
  clear();
}

inline <T>DLList::<T>DLList()
{
  h = 0;
}

inline int <T>DLList::empty()
{
  return h == 0;
}

inline int <T>DLList::length()
{
  int l = 0;
  <T>DLListNode* t = h;
  if (t != 0) do { ++l; t = t->fd; } while (t != h);
  return l;
}

inline void <T>DLList::next(Pix& p)
{
  p = (p == 0 || p == h->bk)? 0 : Pix(((<T>DLListNode*)p)->fd);
}

inline void <T>DLList::prev(Pix& p)
{
  p = (p == 0 || p == h)? 0 : Pix(((<T>DLListNode*)p)->bk);
}

inline Pix <T>DLList::first()
{
  return Pix(h);
}

inline Pix <T>DLList::last()
{
  return (h == 0)? 0 : Pix(h->bk);
}

inline <T>& <T>DLList::operator () (Pix p)
{
  if (p == 0) error("null Pix");
  return ((<T>DLListNode*)p)->hd;
}

inline <T>& <T>DLList::front()
{
  if (h == 0) error("front: empty list");
  return h->hd;
}

inline <T>& <T>DLList::rear()
{
  if (h == 0) error("rear: empty list");
  return h->bk->hd;
}




#endif