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/*
* lists.c -- Functions to implement a double linked list XBoard
*
* Copyright 1995, 2009, 2010, 2011, 2012, 2013, 2014, 2015, 2016 Free
* Software Foundation, Inc.
*
* Enhancements Copyright 2005 Alessandro Scotti
*
* ------------------------------------------------------------------------
*
* GNU XBoard 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 3 of the License, or (at
* your option) any later version.
*
* GNU XBoard 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, see http://www.gnu.org/licenses/. *
*
*------------------------------------------------------------------------
** See the file ChangeLog for a revision history. */
/*
* This file could well be a part of backend.c, but I prefer it this
* way.
*/
#include "config.h"
#include <stdio.h>
#if STDC_HEADERS
# include <stdlib.h>
#endif /* not STDC_HEADERS */
#include "common.h"
#include "lists.h"
/* Check, if List l is empty; returns TRUE, if it is, FALSE
* otherwise.
*/
int
ListEmpty (List *l)
{
return(l->head == (ListNode *) &l->tail);
}
/* Initialize a list. Must be executed before list is used.
*/
void
ListNew (List *l)
{
l->head = (ListNode *) &l->tail;
l->tail = NULL;
l->tailPred = (ListNode *) l;
}
/* Remove node n from the list it is inside.
*/
void
ListRemove (ListNode *n)
{
if (n->succ != NULL) { /* Be safe */
n->pred->succ = n->succ;
n->succ->pred = n->pred;
n->succ = NULL; /* Mark node as no longer being member */
n->pred = NULL; /* of a list. */
}
}
/* Delete node n.
*/
void
ListNodeFree (ListNode *n)
{
if (n) {
ListRemove(n);
free(n);
}
}
/* Create a list node with size s. Returns NULL, if out of memory.
*/
ListNode *
ListNodeCreate (size_t s)
{
ListNode *n;
if ((n = (ListNode*) malloc(s))) {
n->succ = NULL; /* Mark node as not being member of a list. */
n->pred = NULL;
}
return(n);
}
/* Insert node n into the list of node m after m.
*/
void
ListInsert (ListNode *m, ListNode *n)
{
n->succ = m->succ;
n->pred = m;
m->succ = n;
n->succ->pred = n;
}
/* Add node n to the head of list l.
*/
void
ListAddHead (List *l, ListNode *n)
{
ListInsert((ListNode *) &l->head, n);
}
/* Add node n to the tail of list l.
*/
void
ListAddTail (List *l, ListNode *n)
{
ListInsert((ListNode *) l->tailPred, n);
}
/* Return element with number n of list l. (NULL, if n doesn't exist.)
* Counting starts with 0.
*/
ListNode *
ListElem (List *l, int n)
{
ListNode *ln;
for (ln = l->head; ln->succ; ln = ln->succ) {
if (!n--) {
return (ln);
}
}
return(NULL);
}
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