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