Function addListRangeReply

src/t_list.cpp:401–439

A helper for replying with a list's range between the inclusive start and end * indexes as multi-bulk, with support for negative indexes. Note that start * must be less than end or an empty array is returned. When the reverse * argument is set to a non-zero value, the reply is reversed so that elements * are returned from end to start. */

 * argument is set to a non-zero value, the reply is reversed so that elements
 * are returned from end to start. */
void addListRangeReply(client *c, robj_roptr o, long start, long end, int reverse) {
    long rangelen, llen = listTypeLength(o);

    /* Convert negative indexes. */
    if (start < 0) start = llen+start;
    if (end < 0) end = llen+end;
    if (start < 0) start = 0;

    /* Invariant: start >= 0, so this test will be true when end < 0.
     * The range is empty when start > end or start >= length. */
    if (start > end || start >= llen) {
        addReply(c,shared.emptyarray);
        return;
    }
    if (end >= llen) end = llen-1;
    rangelen = (end-start)+1;

    /* Return the result in form of a multi-bulk reply */
    addReplyArrayLen(c,rangelen);
    if (o->encoding == OBJ_ENCODING_QUICKLIST) {
        int from = reverse ? end : start;
        int direction = reverse ? LIST_HEAD : LIST_TAIL;
        listTypeIterator *iter = listTypeInitIterator(o,from,direction);

        while(rangelen--) {
            listTypeEntry entry;
            listTypeNext(iter, &entry);
            quicklistEntry *qe = &entry.entry;
            if (qe->value) {
                addReplyBulkCBuffer(c,qe->value,qe->sz);
            } else {
                addReplyBulkLongLong(c,qe->longval);
            }
        }
        listTypeReleaseIterator(iter);
    } else {
        serverPanic("Unknown list encoding");
    }
}

/* A housekeeping helper for list elements popping tasks. */
void listElementsRemoved(client *c, robj *key, int where, robj *o, long count) {