skiplist/examples/slm.c

93 lines
2.2 KiB
C

#include <stddef.h>
#include <stdlib.h>
#include <stdint.h>
#include "../include/sl.h"
/*
* SKIPLIST EXAMPLE:
*
* This example creates a Skiplist keys and values are integers.
*/
/* Create a type of Skiplist that maps int -> int. */
struct entry {
int key;
int value;
SKIP_ENTRY(entry) entries;
};
SKIP_HEAD(skip, entry);
/* Generate a function to compare keys to order our list.
*
* The function takes three arguments:
* - `a` and `b` of the provided type (`entry` in this case)
* - `aux` an additional auxiliary argument
* and returns:
* a < b : return -1
* a == b : return 0
* a > b : return 1
*
* This function is only called when a and b are not NULL and valid
* pointers to the entry type.
*
* The function will be named: __skip_cmp_<entry> which should be
* passed as the 2nd argument in the SKIP_HEAD_INITIALIZER.
*/
SKIP_COMPARATOR(skip, entry, {
(void)aux;
if (a->key < b->key)
return -1;
if (a->key > b->key)
return 1;
return 0;
})
typedef struct skip skip_t;
int main() {
/* Allocate and initialize a Skiplist. */
#ifdef STATIC_INIT
skip_t _list = SKIP_HEAD_DEFAULT_INITIALIZER(__skip_cmp_entry);
skip_t *list = &_list;
#else /* Dynamic allocation, init. */
skip_t *list = (skip_t *)malloc(sizeof(skip_t));
SKIP_DEFAULT_INIT(list, __skip_cmp_entry);
#endif
/* Insert 10 key/value pairs into the list. */
for (int i = 0; i < 10; i++) {
struct entry *n;
SKIP_ALLOC_NODE(list, n, entry, entries);
n->key = i;
n->value = i;
SKIP_INSERT(list, entry, n, entries);
}
#if 0
/* Delete a specific element in the list. */
struct entry query;
query.key = 4;
struct entry *removed = SKIP_REMOVE(list, q, entries);
free(removed);
/* Forward traversal. */
SKIP_FOREACH(np, &head, entries)
np-> ...
/* Reverse traversal. */
SKIP_FOREACH_REVERSE(np, &head, skiphead, entries)
np-> ...
/* Skiplist Deletion. */
while (!SKIP_EMPTY(&head)) {
n1 = SKIP_FIRST(&head);
SKIP_REMOVE(&head, n1, entries);
free(n1);
}
/* Faster Skiplist Deletion. */
n1 = SKIP_FIRST(&head);
while (n1 != NULL) {
n2 = SKIP_NEXT(n1, entries);
free(n1);
n1 = n2;
}
SKIP_INIT(&head);
#endif
return 0;
}