skiplist/examples/slm.c

#include <sys/time.h>

#include <assert.h>
#include <errno.h>
#include <stddef.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include <unistd.h>

/* 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;
    char *value;
    SKIPLIST_ENTRY(slex_node) entries;
};

/*
 * Generate all the access functions for our type of Skiplist.
 */
SKIPLIST_DECL(
    slex, api_, entries,
    /* free node */ { free(node->value); },
    /* update node */ { node->value = new->value; },
    /* snapshot node */
    {
        new->key = node->key;
        char *nv = calloc(strlen(node->value) + 1, sizeof(char));
        if (nv == NULL)
            return NULL; /* leaks some memory... TODO */
        new->value = strncpy(nv, node->value, strlen(node->value));
    },
    /* size in bytes of the content stored in an entry by you */
    { size = strlen(node->value) + 1; })

/* Optional: Create the functions used to visualize a Skiplist (DOT/Graphviz) */
SKIPLIST_DECL_DOT(slex, api_, entries)

void
sprintf_slex_node(slex_node_t *node, char *buf)
{
    sprintf(buf, "%d:%s", node->key, node->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, char *, { 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;
}

static char *
to_lower(char *str)
{
    char *p = str;
    for (; *p; ++p)
        *p = *p >= 'A' && *p <= 'Z' ? *p | 0x60 : *p;
    return str;
}

static char *
to_upper(char *str)
{
    char *p = str;
    for (; *p; ++p)
        *p = *p >= 'a' && *p <= 'z' ? *p & ~0x20 : *p;
    return str;
}

static char *
int_to_roman_numeral(int num)
{
    int del[] = { 1000, 900, 500, 400, 100, 90, 50, 40, 10, 9, 5, 4, 1 };                    // Key value in Roman counting
    char *sym[] = { "M", "CM", "D", "CD", "C", "XC", "L", "XL", "X", "IX", "V", "IV", "I" }; // Symbols for key values
    // The maximum length of the Roman numeral representation for the maximum signed 64-bit integer would be approximately 19 * 3 = 57 characters, assuming
    // every digit is represented by its Roman numeral equivalent up to 3 repetitions.  Therefore, 64 should be more than enough.
    char *res = (char *)calloc(64, sizeof(char));
    int i = 0;
    if (num < 0) {
        res[0] = '-';
        i++;
        num = -num;
    }
    if (num == 0) {
        res[0] = '0';
        return res;
    }
    while (num) {                // while input number is not zero
        while (num / del[i]) {   // while a number contains the largest key value possible
            strcat(res, sym[i]); // append the symbol for this key value to res string
            num -= del[i];       // subtract the key value from number
        }
        i++; // proceed to the next key value
    }
    return res;
}

void
shuffle(int *array, size_t n)
{
    if (n > 1) {
        size_t i;
        for (i = n - 1; i > 0; i--) {
            size_t j = (unsigned int)(rand() % (i + 1)); /* NOLINT(*-msc50-cpp) */
            int t = array[j];
            array[j] = array[i];
            array[i] = t;
        }
    }
}

#define TEST_ARRAY_SIZE 50

int
main()
{
    int rc = 0;

    /* Allocate and initialize a Skiplist. */
    slex_t *list = (slex_t *)malloc(sizeof(slex_t));
    if (list == NULL)
        return ENOMEM;

    rc = api_skip_init_slex(list, 12, __slm_key_compare);
    if (rc)
        return rc;

    /* Test creating a snapshot of an empty Skiplist */
    slex_snap_t *snap = api_skip_snapshot_slex(list);
    slex_t *restored = api_skip_restore_snapshot_slex(snap, __skip_key_compare_slex);
    api_skip_dispose_snapshot_slex(snap);
    api_skip_destroy_slex(restored);

    /* Insert 7 key/value pairs into the list. */
    int amt = TEST_ARRAY_SIZE, asz = (amt * 2) + 1;
    int array[(TEST_ARRAY_SIZE * 2) + 1];
    for (int j = 0, i = -amt; i <= amt; i++, j++)
        array[j] = i;
    shuffle(array, asz);

    for (int i = 0; i <= asz; i++) {
        struct slex_node *n;
        char *v;
        slex_node_t new;
        rc = api_skip_alloc_node_slex(list, &n);
        if (rc)
            return rc;
        n->key = array[i];
        n->value = to_lower(int_to_roman_numeral(array[i]));
        api_skip_insert_slex(list, n);
        v = api_skip_get_slex(list, array[i]);
        ((void)v);
        new.key = n->key;
        new.value = to_upper(n->value);
        api_skip_update_slex(list, &new);
    }

    slex_node_t q;
    q.key = 0;
    api_skip_remove_slex(list, &q);

    snap = api_skip_snapshot_slex(list);
    restored = api_skip_restore_snapshot_slex(snap, __skip_key_compare_slex);
    api_skip_dispose_snapshot_slex(snap);
    api_skip_destroy_slex(restored);

    assert(api_skip_gte_slex(list, -6) == int_to_roman_numeral(-5));
    assert(api_skip_gte_slex(list, -2) == int_to_roman_numeral(-2));
    assert(api_skip_gte_slex(list, 0) == int_to_roman_numeral(0));
    assert(api_skip_gte_slex(list, 2) == int_to_roman_numeral(2));
    assert(api_skip_gte_slex(list, 6) == int_to_roman_numeral(0));

    assert(api_skip_lte_slex(list, -6) == int_to_roman_numeral(0));
    assert(api_skip_lte_slex(list, -2) == int_to_roman_numeral(-2));
    assert(api_skip_lte_slex(list, 0) == int_to_roman_numeral(-10));
    assert(api_skip_lte_slex(list, 2) == int_to_roman_numeral(2));
    assert(api_skip_lte_slex(list, 6) == int_to_roman_numeral(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);

    return rc;
}