Manu Mtz-Almeida
85 lines
1.7 KiB
Go
85 lines
1.7 KiB
Go
package sse
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import (
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"encoding/json"
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"fmt"
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"io"
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"reflect"
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"strings"
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)
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// Server-Sent Events
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// W3C Working Draft 29 October 2009
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// http://www.w3.org/TR/2009/WD-eventsource-20091029/
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const ContentType = "text/event-stream"
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type Event struct {
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Event string
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Id string
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Retry uint
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Data interface{}
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}
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func Encode(w io.Writer, event Event) error {
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writeId(w, event.Id)
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writeEvent(w, event.Event)
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writeRetry(w, event.Retry)
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return writeData(w, event.Data)
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}
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func writeId(w io.Writer, id string) {
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if len(id) > 0 {
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w.Write([]byte("id: "))
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w.Write([]byte(escape(id)))
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w.Write([]byte("\n"))
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}
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}
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func writeEvent(w io.Writer, event string) {
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if len(event) > 0 {
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w.Write([]byte("event: "))
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w.Write([]byte(escape(event)))
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w.Write([]byte("\n"))
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}
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}
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func writeRetry(w io.Writer, retry uint) {
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if retry > 0 {
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fmt.Fprintf(w, "retry: %d\n", retry)
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}
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}
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func writeData(w io.Writer, data interface{}) error {
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w.Write([]byte("data: "))
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switch typeOfData(data) {
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case reflect.Struct, reflect.Slice, reflect.Map:
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err := json.NewEncoder(w).Encode(data)
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if err != nil {
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return err
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}
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w.Write([]byte("\n"))
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default:
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text := fmt.Sprint(data)
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fmt.Fprint(w, escape(text), "\n\n")
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}
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return nil
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}
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func typeOfData(data interface{}) reflect.Kind {
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value := reflect.ValueOf(data)
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valueType := value.Kind()
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if valueType == reflect.Ptr {
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valueType = value.Elem().Kind()
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}
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return valueType
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}
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func escape(str string) string {
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// any-char = %x0000-0009 / %x000B-000C / %x000E-10FFFF
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// ; a Unicode character other than U+000A LINE FEED (LF) or U+000D CARRIAGE RETURN (CR)
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str = strings.Replace(str, "\n", "\\n", -1)
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str = strings.Replace(str, "\r", "\\r", -1)
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return str
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}
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