📄 list.c
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/*****************************************************************************
* *
* -------------------------------- list.c -------------------------------- *
* *
*****************************************************************************/
#include <stdlib.h>
#include <string.h>
#include "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;
}
/*****************************************************************************
* *
* ----------------------------- list_destroy ----------------------------- *
* *
*****************************************************************************/
void list_destroy(List *list) {
void *data;
/*****************************************************************************
* *
* Remove each element. *
* *
*****************************************************************************/
while (list_size(list) > 0) {
if (list_rem_next(list, NULL, (void **)&data) == 0 && list->destroy !=
NULL) {
/***********************************************************************
* *
* Call a user-defined function to free dynamically allocated data. *
* *
***********************************************************************/
list->destroy(data);
}
}
/*****************************************************************************
* *
* No operations are allowed now, but clear the structure as a precaution. *
* *
*****************************************************************************/
memset(list, 0, sizeof(List));
return;
}
/*****************************************************************************
* *
* ----------------------------- 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;
}
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;
}
/*****************************************************************************
* *
* Adjust the size of the list to account for the inserted element. *
* *
*****************************************************************************/
list->size++;
return 0;
}
/*****************************************************************************
* *
* ----------------------------- 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;
}
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;
}
/*****************************************************************************
* *
* 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;
}
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