/*
 *  call-seq:
 *     iw.add_readers(reader_array) -> iw
 *
 *  Use this method to merge other indexes into the one being written by
 *  IndexWriter. This is useful for parallel indexing. You can have several
 *  indexing processes running in parallel, possibly even on different
 *  machines. Then you can finish by merging all of the indexes into a single
 *  index.
 */
static VALUE
frt_iw_add_readers(VALUE self, VALUE rreaders)
{
    IndexWriter *iw = (IndexWriter *)DATA_PTR(self);
    int i;
    IndexReader **irs;
    Check_Type(rreaders, T_ARRAY);

    irs = ALLOC_N(IndexReader *, RARRAY(rreaders)->len);
    i = RARRAY(rreaders)->len;
    while (i-- > 0) {
        IndexReader *ir;
        Data_Get_Struct(RARRAY(rreaders)->ptr[i], IndexReader, ir);
        irs[i] = ir;
    }
    iw_add_readers(iw, irs, RARRAY(rreaders)->len);
    free(irs);
    return self;
}