path: root/src/references.c

#include "stmd.h"
#include "utf8.h"
#include "references.h"

static unsigned int
refhash(const unsigned char *link_ref)
{
    unsigned int hash = 0;

    while (*link_ref)
        hash = (*link_ref++) + (hash << 6) + (hash << 16) - hash;

    return hash;
}

static void reference_free(reference *ref)
{
    free(ref->label);
    free(ref->url);
    free(ref->title);
    free(ref);
}

// normalize reference:  collapse internal whitespace to single space,
// remove leading/trailing whitespace, case fold
// Return NULL if the reference name is actually empty (i.e. composed
// solely from whitespace)
static unsigned char *normalize_reference(chunk *ref)
{
    strbuf normalized = GH_BUF_INIT;
    unsigned char *result;

    if (ref->len == 0)
        return NULL;

    utf8proc_case_fold(&normalized, ref->data, ref->len);
    strbuf_trim(&normalized);
    strbuf_normalize_whitespace(&normalized);

    result = strbuf_detach(&normalized);
    assert(result);

    if (result[0] == '\0') {
        free(result);
        return NULL;
    }
    
    return result;
}

static void add_reference(reference_map *map, reference* ref)
{
    reference *t = ref->next = map->table[ref->hash % REFMAP_SIZE];

    while (t) {
        if (t->hash == ref->hash &&
            !strcmp((char *)t->label, (char *)ref->label)) {
            reference_free(ref);
            return;
        }

        t = t->next;
    }

    map->table[ref->hash % REFMAP_SIZE] = ref;
}

extern void reference_create(reference_map *map, chunk *label, chunk *url, chunk *title)
{
    reference *ref;
    unsigned char *reflabel = normalize_reference(label);

    /* empty reference name, or composed from only whitespace */
    if (reflabel == NULL)
        return;

    ref = malloc(sizeof(reference));
    ref->label = reflabel;
    ref->hash = refhash(ref->label);
    ref->url = clean_url(url);
    ref->title = clean_title(title);
    ref->next = NULL;

    add_reference(map, ref);
}

// Returns reference if refmap contains a reference with matching
// label, otherwise NULL.
reference* reference_lookup(reference_map *map, chunk *label)
{
    reference *ref = NULL;
    unsigned char *norm;
    unsigned int hash;
    
    if (map == NULL)
        return NULL;
    
    norm = normalize_reference(label);
    if (norm == NULL)
        return NULL;

    hash = refhash(norm);
    ref = map->table[hash % REFMAP_SIZE];

    while (ref) {
        if (ref->hash == hash &&
            !strcmp((char *)ref->label, (char *)norm))
            break;
        ref = ref->next;
    }

    free(norm);
    return ref;
}

void reference_map_free(reference_map *map)
{
    unsigned int i;

    for (i = 0; i < REFMAP_SIZE; ++i) {
        reference *ref = map->table[i];
        reference *next;

        while (ref) {
            next = ref->next;
            reference_free(ref);
            ref = next;
        }
    }

    free(map);
}

reference_map *reference_map_new(void)
{
    reference_map *map = malloc(sizeof(reference_map));
    memset(map, 0x0, sizeof(reference_map));
    return map;
}