#include #include #include #include #include #include #include #include /* Setting this will do two things: * 1) limit our max height across all instances of this datastructure. * 2) remove a heap allocation on frequently used paths, insert/remove/etc. * so, use it when you need it. */ #define SKIPLIST_MAX_HEIGHT 12 #include "../include/sl.h" /* * SKIPLIST EXAMPLE: * * This example creates a Skiplist keys and values are integers. * 'slex' - meaning: SkipList EXample */ /* * 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. */ struct slex_node { int key; int value; SKIP_ENTRY(slex_node) entries; }; /* * Generate all the access functions for our type of Skiplist. */ SKIPLIST_DECL( slex, api_, entries, /* free node */ { (void)node; }, /* update node */ { node->value = new->value; }) /* * Getter * It can be useful to have simple get/put-style API, but to * do that you'll have to supply some blocks of code used to * extract data from within your nodes. */ SKIPLIST_GETTERS( slex, api_, int, int, { query.key = key; }, { return node->value; }) /* * Now we need a way to compare the nodes you defined above. * Let's create a function with 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 function 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 function will not be used when comparing nodes. This will * happen 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. :) */ int __slm_key_compare(slex_t *list, slex_node_t *a, slex_node_t *b, void *aux) { (void)list; (void)aux; if (a->key < b->key) return -1; if (a->key > b->key) return 1; return 0; } #define DOT #ifdef DOT /* Also declare the functions used to visualize a Sliplist (DOT/Graphviz) */ SKIPLIST_DECL_DOT(slex, api_, entries) void sprintf_slex_node(slex_node_t *node, char *buf) { sprintf(buf, "%d:%d", node->key, node->value); } #endif int main() { int rc = 0; /* Allocate and initialize a Skiplist. */ slex_t *list = (slex_t *)malloc(sizeof(slex_t)); if (list == NULL) { rc = ENOMEM; goto fail; } rc = api_skip_init_slex(list, 12, __slm_key_compare); if (rc) return rc; struct slex_node *n; /* Insert 7 key/value pairs into the list. */ for (int i = -50; i <= 50; i++) { int v; slex_node_t new; rc = api_skip_alloc_node_slex(list, &n); if (rc) return rc; n->key = i; n->value = i; api_skip_insert_slex(list, n); v = api_skip_get_slex(list, i); ((void)v); new.key = n->key; new.value = n->value * 10; api_skip_update_slex(list, &new); } slex_node_t q; q.key = 0; api_skip_remove_slex(list, &q); // assert(api_skip_gte_slex(list, -3000000) == -20); assert(api_skip_gte_slex(list, -2) == -20); assert(api_skip_gte_slex(list, 0) == 10); // assert(api_skip_gte_slex(list, 0) == 0); assert(api_skip_gte_slex(list, 2) == 20); assert(api_skip_gte_slex(list, 30000000) == 0); assert(api_skip_lte_slex(list, -3000000) == 0); assert(api_skip_lte_slex(list, -2) == -20); assert(api_skip_lte_slex(list, 0) == -10); // assert(api_skip_lte_slex(list, 0) == 0); assert(api_skip_lte_slex(list, 2) == 20); // assert(api_skip_lte_slex(list, 30000000) == 20); FILE *of = fopen("/tmp/slm.dot", "w"); if (!of) { perror("Failed to open file /tmp/slm.dot"); return EXIT_FAILURE; } api_skip_dot_slex(of, list, 0, sprintf_slex_node); fclose(of); api_skip_destroy_slex(list); fail:; return rc; }