Function zzlFirstInLexRange

src/t_zset.cpp:953–974

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

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

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

    while (eptr != NULL) {
        if (zzlLexValueGteMin(eptr,range)) {
            /* Check if score <= max. */
            if (zzlLexValueLteMax(eptr,range))
                return eptr;
            return NULL;
        }

        /* Move to next element. */
        sptr = ziplistNext(zl,eptr); /* This element score. Skip it. */
        serverAssert(sptr != NULL);
        eptr = ziplistNext(zl,sptr); /* Next element. */
    }

    return NULL;
}

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