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response_writer.go
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response_writer.go
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package martini
import (
"bufio"
"fmt"
"net"
"net/http"
)
// ResponseWriter is a wrapper around http.ResponseWriter that provides extra information about
// the response. It is recommended that middleware handlers use this construct to wrap a responsewriter
// if the functionality calls for it.
type ResponseWriter interface {
http.ResponseWriter
http.Flusher
http.Hijacker
// Status returns the status code of the response or 0 if the response has not been written.
Status() int
// Written returns whether or not the ResponseWriter has been written.
Written() bool
// Size returns the size of the response body.
Size() int
// Before allows for a function to be called before the ResponseWriter has been written to. This is
// useful for setting headers or any other operations that must happen before a response has been written.
Before(BeforeFunc)
}
// BeforeFunc is a function that is called before the ResponseWriter has been written to.
type BeforeFunc func(ResponseWriter)
// NewResponseWriter creates a ResponseWriter that wraps an http.ResponseWriter
func NewResponseWriter(rw http.ResponseWriter) ResponseWriter {
newRw := responseWriter{rw, 0, 0, nil}
if cn, ok := rw.(http.CloseNotifier); ok {
return &closeNotifyResponseWriter{newRw, cn}
}
return &newRw
}
type responseWriter struct {
http.ResponseWriter
status int
size int
beforeFuncs []BeforeFunc
}
func (rw *responseWriter) WriteHeader(s int) {
rw.callBefore()
rw.ResponseWriter.WriteHeader(s)
rw.status = s
}
func (rw *responseWriter) Write(b []byte) (int, error) {
if !rw.Written() {
// The status will be StatusOK if WriteHeader has not been called yet
rw.WriteHeader(http.StatusOK)
}
size, err := rw.ResponseWriter.Write(b)
rw.size += size
return size, err
}
func (rw *responseWriter) Status() int {
return rw.status
}
func (rw *responseWriter) Size() int {
return rw.size
}
func (rw *responseWriter) Written() bool {
return rw.status != 0
}
func (rw *responseWriter) Before(before BeforeFunc) {
rw.beforeFuncs = append(rw.beforeFuncs, before)
}
func (rw *responseWriter) Hijack() (net.Conn, *bufio.ReadWriter, error) {
hijacker, ok := rw.ResponseWriter.(http.Hijacker)
if !ok {
return nil, nil, fmt.Errorf("the ResponseWriter doesn't support the Hijacker interface")
}
return hijacker.Hijack()
}
func (rw *responseWriter) callBefore() {
for i := len(rw.beforeFuncs) - 1; i >= 0; i-- {
rw.beforeFuncs[i](rw)
}
}
func (rw *responseWriter) Flush() {
flusher, ok := rw.ResponseWriter.(http.Flusher)
if ok {
flusher.Flush()
}
}
type closeNotifyResponseWriter struct {
responseWriter
closeNotifier http.CloseNotifier
}
func (rw *closeNotifyResponseWriter) CloseNotify() <-chan bool {
return rw.closeNotifier.CloseNotify()
}