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package eventsource
import (
"bufio"
"io"
"strconv"
"strings"
)
type publication struct {
id, event, data string
retry int64
}
func (s *publication) Id() string { return s.id }
func (s *publication) Event() string { return s.event }
func (s *publication) Data() string { return s.data }
func (s *publication) Retry() int64 { return s.retry }
// A Decoder is capable of reading Events from a stream.
type Decoder struct {
*bufio.Reader
}
// NewDecoder returns a new Decoder instance that reads events
// with the given io.Reader.
func NewDecoder(r io.Reader) *Decoder {
dec := &Decoder{bufio.NewReader(newNormaliser(r))}
return dec
}
// Decode reads the next Event from a stream (and will block until one
// comes in).
// Graceful disconnects (between events) are indicated by an io.EOF error.
// Any error occuring mid-event is considered non-graceful and will
// show up as some other error (most likely io.ErrUnexpectedEOF).
func (dec *Decoder) Decode() (Event, error) {
// peek ahead before we start a new event so we can return EOFs
_, err := dec.Peek(1)
if err == io.ErrUnexpectedEOF {
err = io.EOF
}
if err != nil {
return nil, err
}
pub := new(publication)
inDecoding := false
for {
line, err := dec.ReadString('\n')
if err != nil {
return nil, err
}
if line == "\n" && inDecoding {
// the empty line signals the end of an event
break
} else if line == "\n" && !inDecoding {
// only a newline was sent, so we don't want to publish an empty event but try to read again
continue
}
line = strings.TrimSuffix(line, "\n")
if strings.HasPrefix(line, ":") {
continue
}
sections := strings.SplitN(line, ":", 2)
field, value := sections[0], ""
if len(sections) == 2 {
value = strings.TrimPrefix(sections[1], " ")
}
inDecoding = true
switch field {
case "event":
pub.event = value
case "data":
pub.data += value + "\n"
case "id":
pub.id = value
case "retry":
pub.retry, _ = strconv.ParseInt(value, 10, 64)
}
}
pub.data = strings.TrimSuffix(pub.data, "\n")
return pub, nil
}
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