hash.c

#include <stdio.h>
#include <stdint.h>
#include <stdlib.h>

const uint64_t MAP_ARRAY_LENGTH = 100;

struct map_node {
    uint64_t state;
    void *value;
    struct map_node *next;
};

struct map_node** new_map() {
    struct map_node **array = (struct map_node**)calloc(sizeof(struct map_node*), MAP_ARRAY_LENGTH);
    return array;
}

int free_map_list(struct map_node *list) {
    struct map_node *p;
    for(p = list;p != NULL;) {
        struct map_node *next = p -> next;
        free(p);
        p = next;
    }
    return 0;
}

int free_map(struct map_node **array) {
    int i = 0;
    for(;i < MAP_ARRAY_LENGTH; ++i) {
        if(array[i] != NULL) {
            free_map_list(array[i]);
        }
    }
    return 0;
}

struct map_node* map_node_last(struct map_node *list) 
{
    struct map_node *p = NULL;
    for(p = list; p->next != NULL; p = p->next){}
    return p;
}

struct map_node* map_node_get(struct map_node *list, uint64_t state) {
    struct map_node *p;
    for(p = list; p != NULL; p = p -> next) {
        if(p -> state == state) {
            return p;
        }
    }
    return NULL;
}

uint64_t state(const char *str) {
    uint64_t i;
    uint64_t sum;
    for(i = 0, sum = 0;str[i] != '\0'; ++i, sum += (uint64_t)str[i] * i){}
    return sum;
}

struct map_node **map_add(struct map_node **l, const char *keyStr, void *value) {
    uint64_t s = state(keyStr);
    uint64_t hash = s % MAP_ARRAY_LENGTH;
    struct map_node *node = (struct map_node*)malloc(sizeof(struct map_node));
    node->state = s;
    node->value = value;
    node->next = NULL;
    if(l[hash] == NULL) {
        l[hash] = node;
    } else {
        map_node_last(l[hash])->next = node;
    }
    return l;
}

void *map_get(struct map_node **l, const char *keyStr) {
    uint64_t s = state(keyStr);
    uint64_t hash = s % MAP_ARRAY_LENGTH;
    if(l[hash] == NULL) {
        return NULL;
    } else {
        return map_node_get(l[hash], s)->value;
    }
}

int main(int argc, char **argv) {
    const char *p = "/home/mitou/foo";
    const char *q = "/home/mitou/bar";
    int x = 123;
    int y = 456;
    int *r;
    
    struct map_node **map = new_map();
    map_add(map, p, &x);
    map_add(map, q, &y);

    r = (int *)map_get(map, p);
    printf("%d == %d\n", x, *r);

    r = (int *)map_get(map, q);
    printf("%d == %d\n", y, *r);

    free_map(map);

    return 0;
}