// ChkbookEntries returns a Stream that emits all the entries in a
// checkbook ordered by most recent to least recent. conn is the sqlite
// connection; acctId is the id of the account for which to print entries.
// If acctId does not match a valid account, ChkbookEntries will return an
// error and nil for the Stream. If caller does not exhaust returned
// Stream, it must call Close on it to free up resources.
func ChkbkEntries(conn *sqlite.Conn, acctId int) (functional.Stream, error) {
stmt, err := conn.Prepare("select balance from balances where acct_id = ?")
if err != nil {
return nil, err
}
if err = stmt.Exec(acctId); err != nil {
stmt.Finalize()
return nil, err
}
if !stmt.Next() {
stmt.Finalize()
return nil, errors.New("No balance")
}
var bal int64
if err = stmt.Scan(&bal); err != nil {
stmt.Finalize()
return nil, err
}
stmt.Finalize()
stmt, err = conn.Prepare("select date, name, amount from entries where acct_id = ? order by date desc")
if err != nil {
return nil, err
}
if err = stmt.Exec(acctId); err != nil {
stmt.Finalize()
return nil, err
}
rowStream := functional.ReadRows(CloserStmt{stmt})
return functional.Filter(&BalanceFilterer{bal}, rowStream), nil
}
// Filter creates a new ErrorReportingConsumer whose Consume method applies
// f to the Stream before passing it onto c.
func Filter(
c ErrorReportingConsumer, f functional.Filterer) ErrorReportingConsumer {
return Modify(
c,
func(s functional.Stream) functional.Stream {
return functional.Filter(f, s)
})
}
// Power returns a Stream that emits the power set of items. Next of
// returned Stream emits to an []int that has same length as items.
func Power(items []int) functional.Stream {
len := len(items)
if len == 0 {
return functional.Slice(ess, 0, 1)
}
return functional.Concat(
Power(items[:len-1]),
functional.Deferred(func() functional.Stream {
return functional.Filter(
appendFilterer(items[len-1]),
Power(items[:len-1]))
}))
}
// Power returns a Stream that emits the power set of items. Next of
// returned Stream emits to an []int that has same length as items.
func Power(items []int) functional.Stream {
return functional.NewGenerator(func(e functional.Emitter) {
len := len(items)
if len == 0 {
ptr := e.EmitPtr()
if ptr != nil {
p := ptr.(*[]int)
*p = (*p)[:0]
e.Return(nil)
}
return
}
if functional.EmitAll(Power(items[:len-1]), e) != nil {
return
}
functional.EmitAll(functional.Filter(appendFilterer(items[len-1]), Power(items[:len-1])), e)
})
}
