/* linkedlist.c
 * This file set implements a generic linked list object. It can be used
 * wherever a linke list is required.
 * 
 * NOTE: we do not currently provide a constructor and destructor for the
 * object itself as we assume it will always be part of another strucuture.
 * Having a pointer to it, I think, does not really make sense but costs
 * performance. Consequently, there is is llInit() and llDestroy() and they
 * do what a constructor and destructur do, except for creating the
 * linkedList_t structure itself.
 *
 * File begun on 2007-07-31 by RGerhards
 *
 * Copyright 2007 Rainer Gerhards and Adiscon GmbH.
 *
 * 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., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 *
 * A copy of the GPL can be found in the file "COPYING" in this distribution.
 */
#include "config.h"

#include <stdio.h>
#include <stdlib.h>
#include <assert.h>

#include "rsyslog.h"
#include "linkedlist.h"


/* Initialize an existing linkedList_t structure
 */
rsRetVal llInit(linkedList_t *pThis, rsRetVal (*pEltDestructor)(void*))
{
	assert(pThis != NULL);
	assert(pEltDestructor != NULL);

	pThis->pEltDestruct = pEltDestructor;
	pThis->cmpOp = NULL;
	pThis->pKey = NULL;
	pThis->iNumElts = 0;
	pThis->pRoot = NULL;
	pThis->pLast = NULL;

	return RS_RET_OK;
};
	

/* llDestroy - destroys a COMPLETE linkedList
 */
rsRetVal llDestroy(linkedList_t *pThis)
{
	DEFiRet;
	llElt_t *pElt;
	llElt_t *pEltPrev;

	assert(pThis != NULL);

	pElt = pThis->pRoot;
	while(pElt != NULL) {
		pEltPrev = pElt;
		pElt = pElt->pNext;
		/* we ignore errors during destruction, as we need to try
		 * finish the linked list in any case.
		 */
		pThis->pEltDestruct(pEltPrev->pData);
		free(pEltPrev);
	}

	return iRet;
}


/* get next user data element of a linked list. The caller must also
 * provide a "cookie" to the function. On initial call, it must be
 * NULL. Other than that, the caller is not allowed to to modify the
 * cookie. In the current implementation, the cookie is an actual
 * pointer to the current list element, but this is nothing that the
 * caller should rely on.
 */
rsRetVal llGetNextElt(linkedList_t *pThis, linkedListCookie_t *ppElt, void **ppUsr)
{
	llElt_t *pElt;
	DEFiRet;

	assert(pThis != NULL);
	assert(ppElt != NULL);
	assert(ppUsr != NULL);

	pElt = *ppElt;

	pElt = (pElt == NULL) ? pThis->pRoot : pElt->pNext;

	if(pElt == NULL) {
		iRet = RS_RET_END_OF_LINKEDLIST;
	} else {
		pElt = pThis->pRoot;
		*ppUsr = pElt->pData;
	}

	*ppElt = pElt;

	return iRet;
}

/*
 * vi:set ai:
 */