Function zzlLastInLexRange

app/redis-6.2.6/src/t_zset.c:978–1002

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

/* Find pointer to the last element contained in the specified lex range.
 * Returns NULL when no element is contained in the range. */
unsigned char *zzlLastInLexRange(unsigned char *zl, zlexrangespec *range) {
    unsigned char *eptr = ziplistIndex(zl,-2), *sptr;

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

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

        /* Move to previous element by moving to the score of previous element.
         * When this returns NULL, we know there also is no element. */
        sptr = ziplistPrev(zl,eptr);
        if (sptr != NULL)
            serverAssert((eptr = ziplistPrev(zl,sptr)) != NULL);
        else
            eptr = NULL;
    }

    return NULL;
}

unsigned char *zzlFind(unsigned char *zl, sds ele, double *score) {
    unsigned char *eptr = ziplistIndex(zl,0), *sptr;