response_writer.go
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// Copyright 2014 Manu Martinez-Almeida. All rights reserved.
// Use of this source code is governed by a MIT style
// license that can be found in the LICENSE file.
package gin
import (
"bufio"
"io"
"net"
"net/http"
)
const (
noWritten = -1
defaultStatus = http.StatusOK
)
// ResponseWriter ...
type ResponseWriter interface {
http.ResponseWriter
http.Hijacker
http.Flusher
http.CloseNotifier
// Returns the HTTP response status code of the current request.
Status() int
// Returns the number of bytes already written into the response http body.
// See Written()
Size() int
// Writes the string into the response body.
WriteString(string) (int, error)
// Returns true if the response body was already written.
Written() bool
// Forces to write the http header (status code + headers).
WriteHeaderNow()
// get the http.Pusher for server push
Pusher() http.Pusher
}
type responseWriter struct {
http.ResponseWriter
size int
status int
}
var _ ResponseWriter = &responseWriter{}
func (w *responseWriter) reset(writer http.ResponseWriter) {
w.ResponseWriter = writer
w.size = noWritten
w.status = defaultStatus
}
func (w *responseWriter) WriteHeader(code int) {
if code > 0 && w.status != code {
if w.Written() {
debugPrint("[WARNING] Headers were already written. Wanted to override status code %d with %d", w.status, code)
}
w.status = code
}
}
func (w *responseWriter) WriteHeaderNow() {
if !w.Written() {
w.size = 0
w.ResponseWriter.WriteHeader(w.status)
}
}
func (w *responseWriter) Write(data []byte) (n int, err error) {
w.WriteHeaderNow()
n, err = w.ResponseWriter.Write(data)
w.size += n
return
}
func (w *responseWriter) WriteString(s string) (n int, err error) {
w.WriteHeaderNow()
n, err = io.WriteString(w.ResponseWriter, s)
w.size += n
return
}
func (w *responseWriter) Status() int {
return w.status
}
func (w *responseWriter) Size() int {
return w.size
}
func (w *responseWriter) Written() bool {
return w.size != noWritten
}
// Hijack implements the http.Hijacker interface.
func (w *responseWriter) Hijack() (net.Conn, *bufio.ReadWriter, error) {
if w.size < 0 {
w.size = 0
}
return w.ResponseWriter.(http.Hijacker).Hijack()
}
// CloseNotify implements the http.CloseNotify interface.
func (w *responseWriter) CloseNotify() <-chan bool {
return w.ResponseWriter.(http.CloseNotifier).CloseNotify()
}
// Flush implements the http.Flush interface.
func (w *responseWriter) Flush() {
w.WriteHeaderNow()
w.ResponseWriter.(http.Flusher).Flush()
}
func (w *responseWriter) Pusher() (pusher http.Pusher) {
if pusher, ok := w.ResponseWriter.(http.Pusher); ok {
return pusher
}
return nil
}