linkedlist(3) - Linux man page

Name

linkedlist - a sigularly linked list

Synopsis

#include <mba/linkedlist.h>
int linkedlist_init(struct linkedlist *l, unsigned int max_size, struct
allocator *al);
int linkedlist_deinit(struct linkedlist *l, del_fn data_del, void *context);
struct linkedlist *linkedlist_new(unsigned int max_size, struct allocator
*al);
int linkedlist_del(struct linkedlist *l, del_fn data_del, void *context);
int linkedlist_clear(struct linkedlist *l, del_fn data_del, void *context);

int linkedlist_add(struct linkedlist *l, void *data);
int linkedlist_insert(struct linkedlist *l, unsigned int idx, void *data);
int linkedlist_insert_sorted(struct linkedlist *l,            compare_fn
cmp,            void **replaced,            const void *data);
int linkedlist_is_empty(const struct linkedlist *l);
unsigned int linkedlist_size(const struct linkedlist *l);
void *linkedlist_get(const struct linkedlist *l, unsigned int idx);
void *linkedlist_get_last(const struct linkedlist *l);
void linkedlist_iterate(void *l, iter_t *iter);
void *linkedlist_next(void *l, iter_t *iter);
void *linkedlist_remove(struct linkedlist *l, unsigned int idx);
void *linkedlist_remove_data(struct linkedlist *l, const void *data);
void *linkedlist_remove_last(struct linkedlist *l);

Description

The linkedlist functions manipulate a sigularly linked list of data pointers.

The struct linkedlist * parameter represeting the list being operated on must be valid. If a the list parameter is a null pointer, a null pointer or -1 will be returned and errno will be set to EINVAL.

init: The linkedlist_init function initializes a linkedlist object. The linkedlist will accepts no more than max_size items. If max_size is zero the list will accept no more than MAX_INT items. Memory for list elements will be allocated from the allocator al. It may be necessary to call linkedlist_deinit to release memory from the allocator al.
deinit: The linkedlist_deinit function calls the data_del function if it is not NULL with each data pointer in the list and the context parameter context and then releases memory allocated for list elements.
new
del: The linkedlist_del function deinitializes the list l with the linkedlist_deinit function before freeing l itself.
clear: The linkedlist_clear function clears the list of all elements. If the data_del function is not NULL it will be called with the context argument and each data pointer in the list before releasing memory for list elements.
add: The linkedlist_add function appends a data pointer to the end of the list. If the list has max_size elements, -1 is returned and errno is set to ERANGE.
insert: inserts a data pointer before the item at idx. Ifidxequals the size of the list, the data pointer will be appended to the list.
insert_sorted: The linkedlist_insert_sorted funtion inserts the data pointer data into the linked list l in a position determined by the comparison function cmp which is defined as follows:

typedef int (*compare_fn)(const void *object1, const void *object2);

This function will be called repeatedly with the new data pointer and each data pointer in the list. The following describes the outcome of the insertion based on the return value of the compare_fn:

> 0 - No operation is performed. The next data element in the list is compared.
== 0 - If the replaced parameter is not NULL the replaced data pointer is assigned to it, removed from the list, and the new pointer is inserted in it's place. If the replaced parameter is NULL the new data pointer is inserted before the equal element.
< 0 - The new data pointer is inserted before the compared element.

For example, the expression (compare_fn)strcoll would be a suitable compare_fn for multibyte strings.

is_empty

tests if the list is empty.

size

returns the number of items in the list.

get

The linkedlist_get function retrieves an item from the list by index. If elements are accessed forward-sequentially each call is an O(1) operation.

get_last

The linkedlist_get_last function retrieves the last data pointer in the list.

iterate, next

Enumerate each element in the list. The linkedlist_iterate function initializes the iter object to point to the first item in the list. Each subsequent call to linkedlist_next returns the next element in the list or NULL if all elements have been enumerated. The elements are returned in order.

Because linkedlist uses an element index for the state of an interator, after a data object returned by linkedlist_next is removed a subsequent call to linkedlist_next will skip an element. Therefore, to remove elements during iteration, linkedlist_get should be used instead. This will have no performance impact as sequential access is O(1) optimized.

To enumerate each element in a list the following code might be used:

iter_t iter;
linkedlist_iterate(lst, &iter);
while ((el = linkedlist_next(lst, &iter)) {
    /* use el */
}

remove: The linkedlist_remove function removes the data pointer at idx from the list. Please refer to the description of linkedlist_iterate for important information regarding the removal of elements during an iteration.
remove_data: The linkedlist_remove_data function removes the data pointer data from the list l. Please refer to the description of linkedlist_iterate for important information regarding the removal of elements during an iteration.
remove_last: The linkedlist_remove_last function removes the last data pointer in the list.

Returns

init: The linkedlist_init function returns -1 if sets errno to an appropriate value if the operation failed or 0 if the list was successfully initialized.
deinit: The linkedlist_deinit function returns -1 and sets errno to an appropriate value if the operation failed or 0 if the list was successfully deinitialized.
new: The linkedlist_new function allocates memory from the allocator al, initializes it with the linkedlist_init function and returns a pointer to the a new linkedlist object. If memory for the linkedlist cannot be allocated a null pointer is returned and errno is set appropriately.
add: The linkedlist_insert function returns 0 if the operation was successful and -1 if an error occurred in which case errno will be set appropriately.
insert: The linkedlist_insert function returns 0 if the operation was successful and -1 if an error occurred in which case errno will be set appropriately.
insert_sorted: The linkedlist_insert_sorted function returns 0 if the operation was successful and -1 if an error occurred in which case errno will be set appropriately.
is_empty: non-zero if the list is empty and zero otherwise.
get: The linkedlist_get function returns the data pointer being retrieved. If the specified idx was out of range, a null pointer is returned and errno is set appropriately.
get_last: The linkedlist_get_last function returns the data pointer or a null pointer if the list is empty.
next: The linkedlist_next function returns the next data pointer in the list or NULL if all elements have been enumerated.
remove: the data pointer removed from the list.
remove_data: the data pointer removed from the list.
remove_last: The linkedlist_remove_last function returns the data pointer removed from the list.