83 lines
1.6 KiB
Go
83 lines
1.6 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 common
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import (
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"fmt"
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"io"
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"net/http"
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"strings"
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)
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type stringWriter interface {
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io.Writer
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writeString(string) (int, error)
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}
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type stringWrapper struct {
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io.Writer
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}
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func (w stringWrapper) writeString(str string) (int, error) {
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return w.Writer.Write([]byte(str))
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}
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func checkWriter(writer io.Writer) stringWriter {
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if w, ok := writer.(stringWriter); ok {
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return w
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} else {
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return stringWrapper{writer}
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}
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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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var contentType = []string{"text/event-stream"}
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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 CustomEvent 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 CustomEvent) error {
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w := checkWriter(writer)
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return writeData(w, event.Data)
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}
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func writeData(w stringWriter, data interface{}) error {
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dataReplacer.WriteString(w, fmt.Sprint(data))
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if strings.HasPrefix(data.(string), "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 CustomEvent) 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 CustomEvent) 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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