skiplist/examples/slm.c

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#include <stdio.h>
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#include <stdlib.h>
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#include <stddef.h>
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#include <stdint.h>
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#include <errno.h>
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#include <string.h>
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#include "../include/sl.h"
/*
* SKIPLIST EXAMPLE:
*
* This example creates a Skiplist keys and values are integers.
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* 'slex' - meaning: SkipList EXample
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*/
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/*
* To start, you must create a type node that will contain the
* fields you'd like to maintain in your Skiplist. In this case
* we map int -> int, but what you put here is up to you. You
* don't even need a "key", just a way to compare one node against
* another, logic you'll provide in SKIP_DECL as a block below.
*/
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struct slex_node {
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int key;
int value;
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SKIP_ENTRY(slex_node) entries;
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};
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/*
* Generate all the access functions for our type of Skiplist.
* The last argument to this macro is a block of code used to
* compare the nodes you defined above.
* This block can expect four arguments:
* - a reference to the Skiplist, `slist`
* - the two nodes to compare, `a` and `b`
* - and `aux`, which you can use to pass into this function
* any additional information required to compare objects.
* `aux` is passed from the value in the Skiplist, you can
* modify that value at any time to suit your needs.
*
* Your block should result in a return statement:
* a < b : return -1
* a == b : return 0
* a > b : return 1
*
* This result provides the ordering within the Skiplist. Sometimes
* your block of code will not be used when comparing nodes. This
* happens when `a` or `b` are references to the head or tail of the
* list or when `a == b`. In those cases the comparison function
* returns before using the code in your block, don't panic. :)
*/
SKIPLIST_DECL(slex, api_, entries, {
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(void)aux;
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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int main() {
/* Allocate and initialize a Skiplist. */
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slex_t _list = SKIP_HEAD_DEFAULT_INITIALIZER(__skip_key_compare_slex);
_list.slh_tail = (struct slex_node *)&_list.slh_head; // TODO...
/* Dynamic allocation, init. */
slex_t *list = (slex_t *)malloc(sizeof(slex_t));
SKIP_DEFAULT_INIT(list, __skip_key_compare_slex, slex_node, entries);
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#ifdef STATIC_INIT
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free(list);
slex_t *list = &_list;
#else
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#endif
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struct slex_node *n;
SKIP_ALLOC_NODE(list, n, slex_node, entries);
n->key = -1;
n->value = -1;
api_skip_insert_slex(list, n);
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api_skip_dot_slex(NULL, list);
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/* Insert 10 key/value pairs into the list. */
for (int i = 0; i < 10; i++) {
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SKIP_ALLOC_NODE(list, n, slex_node, entries);
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n->key = i;
n->value = i;
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api_skip_insert_slex(list, n);
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}
#if 0
/* Delete a specific element in the list. */
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struct slex_node query;
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query.key = 4;
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struct slex_node *removed = SKIP_REMOVE(list, q, entries);
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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;
}