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|
package eventsource
import (
"compress/gzip"
"fmt"
"io"
"strings"
)
var (
encFields = []struct {
prefix string
value func(Event) string
}{
{"id: ", Event.Id},
{"event: ", Event.Event},
{"data: ", Event.Data},
}
)
// An Encoder is capable of writing Events to a stream. Optionally
// Events can be gzip compressed in this process.
type Encoder struct {
w io.Writer
compressed bool
}
// NewEncoder returns an Encoder for a given io.Writer.
// When compressed is set to true, a gzip writer will be
// created.
func NewEncoder(w io.Writer, compressed bool) *Encoder {
if compressed {
return &Encoder{w: gzip.NewWriter(w), compressed: true}
}
return &Encoder{w: w}
}
// Encode writes an event in the format specified by the
// server-sent events protocol.
func (enc *Encoder) Encode(ev Event) error {
for _, field := range encFields {
prefix, value := field.prefix, field.value(ev)
if len(value) == 0 {
continue
}
value = strings.Replace(value, "\n", "\n"+prefix, -1)
if _, err := io.WriteString(enc.w, prefix+value+"\n"); err != nil {
return fmt.Errorf("eventsource encode: %v", err)
}
}
if _, err := io.WriteString(enc.w, "\n"); err != nil {
return fmt.Errorf("eventsource encode: %v", err)
}
if enc.compressed {
return enc.w.(*gzip.Writer).Flush()
}
return nil
}
|
