//  VirtualDub 2.x (Nina) - Video processing and capture application
//  Copyright (C) 1998-2001 Avery Lee, All Rights Reserved.
//
//  This program is free software; you can redistribute it and/or modify
//  it under the terms of the GNU General Public License as published by
//  the Free Software Foundation; either version 2 of the License, or
//  (at your option) any later version.
//
//  This program is distributed in the hope that it will be useful,
//  but WITHOUT ANY WARRANTY; without even the implied warranty of
//  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
//  GNU General Public License for more details.
//
//  You should have received a copy of the GNU General Public License
//  along with this program; if not, write to the Free Software
//  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.

//
// Modified by Julien 'Cyrius' Coloos
// 20-09-2003
//

///////////////////////////////////////////////////////////////////////////
//
//  For those of you who say this looks familiar... it should.  This is
//  the same linked-list style that the Amiga Exec uses, with dummy head
//  and tail nodes.  It's really a very convienent way to implement
//  doubly-linked lists.
//

#include <algorithm>
#include "list.h"

List::List() {
  Init();
}

void List::Init() {
  head.next = tail.prev = 0;
  head.prev = &tail;
  tail.next = &head;
}

ListNode *List::RemoveHead() {
  if (head.prev->prev) {
    ListNode *t = head.prev;

    head.prev->Remove();
    return t;
  }

  return 0;
}

ListNode *List::RemoveTail() {
  if (tail.next->next) {
    ListNode *t = tail.next;

    tail.next->Remove();
    return t;
  }

  return 0;
}

void List::Take(List &from) {
  if (from.IsEmpty())
    return;

  head.prev = from.head.prev;
  tail.next = from.tail.next;
  head.prev->next = &head;
  tail.next->prev = &tail;

  from.Init();
}

void List::Swap(List &dst) {
  if (IsEmpty())
    Take(dst);
  else if (dst.IsEmpty())
    dst.Take(*this);
  else {
    std::swap(head.prev, dst.head.prev);
    std::swap(tail.next, dst.tail.next);

    head.prev->next = &head;
    tail.next->prev = &tail;

    dst.head.prev->next = &dst.head;
    dst.tail.next->prev = &dst.tail;
  }
}