Function zzlFirstInRange

app/redis-6.2.6/src/t_zset.c:855–879

Find pointer to the first element contained in the specified range. * Returns NULL when no element is contained in the range. */

/* Find pointer to the first element contained in the specified range.
 * Returns NULL when no element is contained in the range. */
unsigned char *zzlFirstInRange(unsigned char *zl, zrangespec *range) {
    unsigned char *eptr = ziplistIndex(zl,0), *sptr;
    double score;

    /* If everything is out of range, return early. */
    if (!zzlIsInRange(zl,range)) return NULL;

    while (eptr != NULL) {
        sptr = ziplistNext(zl,eptr);
        serverAssert(sptr != NULL);

        score = zzlGetScore(sptr);
        if (zslValueGteMin(score,range)) {
            /* Check if score <= max. */
            if (zslValueLteMax(score,range))
                return eptr;
            return NULL;
        }

        /* Move to next element. */
        eptr = ziplistNext(zl,sptr);
    }

    return NULL;
}

/* Find pointer to the last element contained in the specified range.
 * Returns NULL when no element is contained in the range. */