/*
 * dlist.c -- double linked list data structure
 * (C)Copyright 1998, 99 by Hiroshi Takekawa
 * This file is not part of any package.
 *
 * Last Modified: Mon Oct 18 21:28:47 1999.
 * $Id: dlist.c,v 1.5 1999/10/18 12:29:11 sian Exp $
 *
 * Enfle 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.
 *
 * Enfle 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., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
 */

#include "dlist.h"

Dlist *
dlist_create(void)
{
  return (Dlist *)calloc(1, sizeof(Dlist));
}

int
dlist_destroy(Dlist *p, int f)
{
  Dlist_data *t, *tn;

  for (t = p->top; t != NULL; t = tn) {
    tn = t->next;
    if (!dlist_delete(p, t, f))
      return 0;
  }
  free(p);

  return 1;
}

Dlist_data *
dlist_add(Dlist *p, void *d)
{
  Dlist_data *t;

  if ((t = (Dlist_data *)calloc(1, sizeof(Dlist_data))) == NULL)
    return NULL;

  t->data = d;

  if (p->top == NULL)
    p->top = t;
  else {
    p->head->next = t;
    t->prev = p->head;
  }
  p->head = t;
  p->ndata++;

  return t;
}

Dlist_data *
dlist_stradd(Dlist *p, char *str)
{
  Dlist_data *t;

  if (str == NULL)
    return NULL;

  if ((t = (Dlist_data *)calloc(1, sizeof(Dlist_data))) == NULL)
    return NULL;

  if ((t->data = strdup(str)) == NULL) {
    free(t);
    return NULL;
  }

  if (p->top == NULL)
    p->top = t;
  else {
    p->head->next = t;
    t->prev = p->head;
  }
  p->head = t;
  p->ndata++;

  return t;
}

static void
detach(Dlist *p, Dlist_data *t)
{
  if (t) {
    if (t->prev == NULL && t->next == NULL)
      p->top = p->head = NULL;
    else {
      if (t->prev)
	t->prev->next = t->next;
      else {
	t->next->prev = NULL;
	p->top = t->next;
      }

      if (t->next)
	t->next->prev = t->prev;
      else {
	t->prev->next = NULL;
	p->head = t->prev;
      }
    }
  } else
    fprintf(stderr, "attempt to detach NULL\n");
}

int
dlist_delete(Dlist *p, Dlist_data *t, int f)
{
  if (p == NULL || t == NULL)
    return 0;

  detach(p, t);

  if (f && t->data != NULL)
    free(t->data);
  free(t);
  p->ndata--;

  return 1;
}

int
dlist_move_to_top(Dlist *p, Dlist_data *t)
{
  if (p == NULL || t == NULL)
    return 0;
  if (p->top == t)
    return 1;

  detach(p, t);

  t->prev = NULL;
  p->top->prev = t;
  t->next = p->top;
  p->top = t;

  return 1;
}

Dlist_data *
dlist_gettop(Dlist *p)
{
  return p->top;
}

Dlist_data *
dlist_gethead(Dlist *p)
{
  return p->head;
}

int
dlist_getndata(Dlist *p)
{
  return p->ndata;
}