DBM#empty?

static VALUE
fdbm_empty_p(VALUE obj)
{
    datum key;
    struct dbmdata *dbmp;
    DBM *dbm;

    GetDBM2(obj, dbmp, dbm);
    if (dbmp->di_size < 0) {
        dbm = dbmp->di_dbm;

        for (key = dbm_firstkey(dbm); key.dptr; key = dbm_nextkey(dbm)) {
            return Qfalse;
        }
    }
    else {
        if (dbmp->di_size)
            return Qfalse;
    }
    return Qtrue;
}