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package framing
import (
"io"
"io/ioutil"
)
type Error string
func (err Error) Error() string { return string(err) }
const (
ErrorUnderrun = Error("frame underrun, unexpected EOF")
ErrorBadSize = Error("bad frame size")
ErrorOversizedFrame = Error("oversized frame, max size exceeded")
)
type (
// Reader generates data frames from some source, returning io.EOF when the end of the input stream is
// detected.
Reader interface {
ReadFrame() (frame []byte, err error)
}
// ReaderFunc is the functional adaptation of Reader.
ReaderFunc func() ([]byte, error)
// Writer sends whole frames to some endpoint; returns io.ErrShortWrite if the frame is only partially written.
Writer interface {
WriteFrame(frame []byte) error
}
// WriterFunc is the functional adaptation of Writer.
WriterFunc func([]byte) error
)
func (f ReaderFunc) ReadFrame() ([]byte, error) { return f() }
func (f WriterFunc) WriteFrame(b []byte) error { return f(b) }
var _ = Reader(ReaderFunc(nil))
var _ = Writer(WriterFunc(nil))
// EOFReaderFunc always returns nil, io.EOF; it implements the ReaderFunc API.
func EOFReaderFunc() ([]byte, error) { return nil, io.EOF }
var _ = ReaderFunc(EOFReaderFunc) // sanity check
// ReadAll returns a reader func that returns the complete contents of `r` in a single frame.
// A zero length frame is treated as an "end of stream" condition, returning io.EOF.
func ReadAll(r io.Reader) ReaderFunc {
return func() (b []byte, err error) {
b, err = ioutil.ReadAll(r)
if len(b) == 0 && err == nil {
err = io.EOF
}
return
}
}
// WriterFor adapts an io.Writer to the Writer interface. All buffers are written to `w` without decoration or
// modification.
func WriterFor(w io.Writer) WriterFunc {
return func(b []byte) error {
n, err := w.Write(b)
if err == nil && n != len(b) {
return io.ErrShortWrite
}
return err
}
}
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