src/list.c

/*
  This File is copied from
  
  http://www.oreilly.com/catalog/masteralgoc/index.html
  Mastering Algorithms with C
  By Kyle Loudon
  ISBN: 1-56592-453-3
  Publishd by O'Reilly
  
 */

/*****************************************************************************
 *                                                                            *
 *  -------------------------------- list.c --------------------------------  *
 *                                                                            *
 *****************************************************************************/

#include <stdlib.h>
#include <string.h>

#include <common/list.h>

/*****************************************************************************
*                                                                            *
*  ------------------------------- list_init ------------------------------  *
*                                                                            *
*****************************************************************************/

void list_init(List *list, void (*destroy)(void *data)) {

	/*********************************************************************
	 *                                                                    *
	 *  Initialize the list.                                              *
	 *                                                                    *
	 *********************************************************************/

	list->size = 0;
	list->destroy = destroy;
	list->head = NULL;
	list->tail = NULL;
	return;
} /* end list_init() */

/*****************************************************************************
 *                                                                            *
 *  ----------------------------- list_destroy -----------------------------  *
 *                                                                            *
 *****************************************************************************/

void list_destroy(List *list) {

	void               *data;
	int rc; 

	/*********************************************************************
	 *                                                                    *
	 *  Remove each element.                                              *
	 *                                                                    *
	 *********************************************************************/

	while (list_size(list) > 0) {
    
		rc = list_rem_next(list, NULL, (void **)&data);
    
		if (( rc == 0) && (list->destroy != NULL)) { 

			/*******************************************************************
			 *                                                                  *
			 *  Call a user-defined function to free dynamically allocated data.*
			 *                                                                  *
			 *******************************************************************/

			list->destroy(data);
		}/* end if() */
	}/* end while() */

	/**************************************************************************
	 *                                                                         *
	 *  No operations are allowed now, but clear the structure as a precaution.*
	 *                                                                         *
	 **************************************************************************/

	memset(list, 0, sizeof(List));
	return;
} /* void list_destroy(List *list) */

/*****************************************************************************
 *                                                                            *
 *  ----------------------------- list_ins_next ----------------------------  *
 *                                                                            *
 *****************************************************************************/

int list_ins_next(List *list, ListElmt *element, const void *data) {

	ListElmt           *new_element;

	/*********************************************************************
	 *                                                                    *
	 *  Allocate storage for the element.                                 *
	 *                                                                    *
	 *********************************************************************/

	if ((new_element = (ListElmt *)malloc(sizeof(ListElmt))) == NULL)
		return -1;

	/*********************************************************************
	 *                                                                    *
	 *  Insert the element into the list.                                 *
	 *                                                                    *
	 *********************************************************************/

	new_element->data = (void *)data;

	if (element == NULL) {

		/*************************************************************
		 *                                                            *
		 *  Handle insertion at the head of the list.                 *
		 *                                                            *
		 *************************************************************/

		if (list_size(list) == 0)
			list->tail = new_element;

		new_element->next = list->head;
		list->head = new_element;
	}/* end if (element == NULL) */
	else {

		/*************************************************************
		 *                                                            *
		 *  Handle insertion somewhere other than at the head.        *
		 *                                                            *
		 *************************************************************/

		if (element->next == NULL)
			list->tail = new_element;

		new_element->next = element->next;
		element->next = new_element;
	}/* end else */

	/*********************************************************************
	 *                                                                    *
	 *  Adjust the size of the list to account for the inserted element.  *
	 *                                                                    *
	 *********************************************************************/

	list->size++;
	return 0;
} /* end list_ins_next() */

/*****************************************************************************
 *                                                                            *
 *  ----------------------------- list_rem_next ----------------------------  *
 *                                                                            *
 *****************************************************************************/

int list_rem_next(List *list, ListElmt *element, void **data) {

	ListElmt           *old_element;

	/*********************************************************************
	 *                                                                    *
	 *  Do not allow removal from an empty list.                          *
	 *                                                                    *
	 *********************************************************************/

	if (list_size(list) == 0)
		return -1;

	/*********************************************************************
	 *                                                                    *
	 *  Remove the element from the list.                                 *
	 *                                                                    *
	 *********************************************************************/

	if (element == NULL) {

		/*************************************************************
		 *                                                            *
		 *  Handle removal from the head of the list.                 *
		 *                                                            *
		 *************************************************************/

		*data = list->head->data;
		old_element = list->head;
		list->head = list->head->next;

		if (list_size(list) == 1)
			list->tail = NULL;
	}/* end if (element == NULL) */
	else {

		/*************************************************************
		 *                                                            *
		 *  Handle removal from somewhere other than the head.        *
		 *                                                            *
		 *************************************************************/

		if (element->next == NULL)
			return -1;

		*data = element->next->data;
		old_element = element->next;
		element->next = element->next->next;

		if (element->next == NULL)
			list->tail = element;
	}/* end else */

	/*********************************************************************
	 *                                                                    *
	 *  Free the storage allocated by the abstract data type.             *
	 *                                                                    *
	 *********************************************************************/

	free(old_element);

	/*********************************************************************
	 *                                                                    *
	 *  Adjust the size of the list to account for the removed element.   *
	 *                                                                    *
	 *********************************************************************/

	list->size--;
	return 0;
}

/*
 * Local variables:
 *  c-indent-level: 8
 *  c-basic-offset: 8
 * End:
 */