/*
 *  call-seq:
 *     index_reader.fields -> array of field-names
 *
 *  Returns an array of field names in the index. This can be used to pass to
 *  the QueryParser so that the QueryParser knows how to expand the "*"
 *  wild-card to all fields in the index. A list of field names can also be
 *  gathered from the FieldInfos object.
 */
static VALUE
frt_ir_fields(VALUE self)
{
    IndexReader *ir = (IndexReader *)DATA_PTR(self);
    FieldInfos *fis = ir->fis;
    VALUE rfield_names = rb_ary_new();
    int i;
    for (i = 0; i < fis->size; i++) {
        rb_ary_push(rfield_names, ID2SYM(rb_intern(fis->fields[i]->name)));
    }
    return rfield_names;
}