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