Function lposCommand

src/t_list.cpp:592–689

LPOS key element [RANK rank] [COUNT num-matches] [MAXLEN len] * * The "rank" is the position of the match, so if it is 1, the first match * is returned, if it is 2 the second match is returned and so forth. * It is 1 by default. If negative has the same meaning but the search is * performed starting from the end of the list. * * If COUNT is given, instead of returning the single element, a

 * The returned elements indexes are always referring to what LINDEX
 * would return. So first element from head is 0, and so forth. */
void lposCommand(client *c) {
    robj_roptr o;
    robj *ele = c->argv[2];
    int direction = LIST_TAIL;
    long rank = 1, count = -1, maxlen = 0; /* Count -1: option not given. */

    if (sdslen(szFromObj(ele)) > LIST_MAX_ITEM_SIZE) {
        addReplyError(c, "Element too large");
        return;
    }

    /* Parse the optional arguments. */
    for (int j = 3; j < c->argc; j++) {
        char *opt = szFromObj(c->argv[j]);
        int moreargs = (c->argc-1)-j;

        if (!strcasecmp(opt,"RANK") && moreargs) {
            j++;
            if (getLongFromObjectOrReply(c, c->argv[j], &rank, NULL) != C_OK)
                return;
            if (rank == 0) {
                addReplyError(c,"RANK can't be zero: use 1 to start from "
                                "the first match, 2 from the second, ...");
                return;
            }
        } else if (!strcasecmp(opt,"COUNT") && moreargs) {
            j++;
            if (getPositiveLongFromObjectOrReply(c, c->argv[j], &count,
              "COUNT can't be negative") != C_OK)
                return;
        } else if (!strcasecmp(opt,"MAXLEN") && moreargs) {
            j++;
            if (getPositiveLongFromObjectOrReply(c, c->argv[j], &maxlen, 
              "MAXLEN can't be negative") != C_OK)
                return;
        } else {
            addReplyErrorObject(c,shared.syntaxerr);
            return;
        }
    }

    /* A negative rank means start from the tail. */
    if (rank < 0) {
        rank = -rank;
        direction = LIST_HEAD;
    }

    /* We return NULL or an empty array if there is no such key (or
     * if we find no matches, depending on the presence of the COUNT option. */
    if ((o = lookupKeyRead(c->db,c->argv[1])) == nullptr) {
        if (count != -1)
            addReply(c,shared.emptyarray);
        else
            addReply(c,shared.null[c->resp]);
        return;
    }
    if (checkType(c,o,OBJ_LIST)) return;