111 lines
2.2 KiB
Go
111 lines
2.2 KiB
Go
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// Copyright 2014 Manu Martinez-Almeida. All rights reserved.
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// Use of this source code is governed by a MIT style
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// license that can be found in the LICENSE file.
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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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"net/http"
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"reflect"
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"strconv"
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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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var contentType = []string{ContentType}
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var noCache = []string{"no-cache"}
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var fieldReplacer = strings.NewReplacer(
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"\n", "\\n",
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"\r", "\\r")
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var dataReplacer = strings.NewReplacer(
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"\n", "\ndata:",
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"\r", "\\r")
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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(writer io.Writer, event Event) error {
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w := checkWriter(writer)
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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 stringWriter, id string) {
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if len(id) > 0 {
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w.WriteString("id:")
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fieldReplacer.WriteString(w, id)
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w.WriteString("\n")
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}
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}
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func writeEvent(w stringWriter, event string) {
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if len(event) > 0 {
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w.WriteString("event:")
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fieldReplacer.WriteString(w, event)
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w.WriteString("\n")
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}
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}
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func writeRetry(w stringWriter, retry uint) {
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if retry > 0 {
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w.WriteString("retry:")
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w.WriteString(strconv.FormatUint(uint64(retry), 10))
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w.WriteString("\n")
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}
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}
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func writeData(w stringWriter, data interface{}) error {
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w.WriteString("data:")
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switch kindOfData(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.WriteString("\n")
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default:
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dataReplacer.WriteString(w, fmt.Sprint(data))
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w.WriteString("\n\n")
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}
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return nil
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}
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func (r Event) Render(w http.ResponseWriter) error {
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r.WriteContentType(w)
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return Encode(w, r)
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}
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func (r Event) WriteContentType(w http.ResponseWriter) {
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header := w.Header()
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header["Content-Type"] = contentType
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if _, exist := header["Cache-Control"]; !exist {
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header["Cache-Control"] = noCache
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}
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}
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func kindOfData(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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