gin-gonic__gin/response_writer.go

// 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"
	"log"
	"net"
	"net/http"
)

const (
	noWritten     = -1
	defaultStatus = 200
)

type (
	ResponseWriter interface {
		http.ResponseWriter
		http.Hijacker
		http.Flusher
		http.CloseNotifier

		Status() int
		Size() int
		Written() bool
		WriteHeaderNow()
	}

	responseWriter struct {
		http.ResponseWriter
		size   int
		status int
	}
)

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() {
			log.Println("[GIN] WARNING. Headers were already written!")
		}
	}
}

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) Status() int {
	return w.status
}

func (w *responseWriter) Size() int {
	return w.size
}

func (w *responseWriter) Written() bool {
	return w.size != noWritten
}

// Implements the http.Hijacker interface
func (w *responseWriter) Hijack() (net.Conn, *bufio.ReadWriter, error) {
	w.size = 0 // this prevents Gin to write the HTTP headers
	return w.ResponseWriter.(http.Hijacker).Hijack()
}

// Implements the http.CloseNotify interface
func (w *responseWriter) CloseNotify() <-chan bool {
	return w.ResponseWriter.(http.CloseNotifier).CloseNotify()
}

// Implements the http.Flush interface
func (w *responseWriter) Flush() {
	w.ResponseWriter.(http.Flusher).Flush()
}