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// Copyright 2009 The Go Authors. All rights reserved.
// Copyright 2012 The Gorilla Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package rpc
import (
"compress/flate"
"compress/gzip"
"io"
"net/http"
"strings"
"unicode"
)
// gzipWriter writes and closes the gzip writer.
type gzipWriter struct {
w *gzip.Writer
}
func (gw *gzipWriter) Write(p []byte) (n int, err error) {
defer gw.w.Close()
return gw.w.Write(p)
}
// gzipEncoder implements the gzip compressed http encoder.
type gzipEncoder struct {
}
func (enc *gzipEncoder) Encode(w http.ResponseWriter) io.Writer {
w.Header().Set("Content-Encoding", "gzip")
return &gzipWriter{gzip.NewWriter(w)}
}
// flateWriter writes and closes the flate writer.
type flateWriter struct {
w *flate.Writer
}
func (fw *flateWriter) Write(p []byte) (n int, err error) {
defer fw.w.Close()
return fw.w.Write(p)
}
// flateEncoder implements the flate compressed http encoder.
type flateEncoder struct {
}
func (enc *flateEncoder) Encode(w http.ResponseWriter) io.Writer {
fw, err := flate.NewWriter(w, flate.DefaultCompression)
if err != nil {
return w
}
w.Header().Set("Content-Encoding", "deflate")
return &flateWriter{fw}
}
// CompressionSelector generates the compressed http encoder.
type CompressionSelector struct {
}
// acceptedEnc returns the first compression type in "Accept-Encoding" header
// field of the request.
func acceptedEnc(req *http.Request) string {
encHeader := req.Header.Get("Accept-Encoding")
if encHeader == "" {
return ""
}
encTypes := strings.FieldsFunc(encHeader, func(r rune) bool {
return unicode.IsSpace(r) || r == ','
})
for _, enc := range encTypes {
if enc == "gzip" || enc == "deflate" {
return enc
}
}
return ""
}
// Select method selects the correct compression encoder based on http HEADER.
func (_ *CompressionSelector) Select(r *http.Request) Encoder {
switch acceptedEnc(r) {
case "gzip":
return &gzipEncoder{}
case "flate":
return &flateEncoder{}
}
return DefaultEncoder
}
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