refactor encoder package

context/acceptencoder.go

@@ -0,0 +1,137 @@
+// Copyright 2015 beego Author. All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package context
+
+import (
+	"compress/flate"
+	"compress/gzip"
+	"io"
+	"net/http"
+	"os"
+	"strconv"
+	"strings"
+
+	"bytes"
+)
+
+// WriteFile reads from file and writes to writer by the specific encoding(gzip/deflate)
+
+func WriteFile(encoding string, writer io.Writer, file *os.File) (bool, string, error) {
+	return writeLevel(encoding, writer, file, flate.BestCompression)
+}
+
+// WriteBody reads  writes content to writer by the specific encoding(gzip/deflate)
+
+func WriteBody(encoding string, writer io.Writer, content []byte) (bool, string, error) {
+	return writeLevel(encoding, writer, bytes.NewBuffer(content), flate.BestSpeed)
+}
+
+// writeLevel reads from reader,writes to writer by specific encoding and compress level
+// the compress level is defined by deflate package
+
+func writeLevel(encoding string, writer io.Writer, reader io.Reader, level int) (bool, string, error) {
+	var outputWriter io.Writer
+	var err error
+	if cf, ok := encoderMap[encoding]; ok {
+		outputWriter, err = cf.encode(writer, level)
+	} else {
+		encoding = ""
+		outputWriter, err = noneCompress(writer, level)
+	}
+	if err != nil {
+		return false, "", err
+	}
+	if _, err = io.Copy(outputWriter, reader); err != nil {
+		return false, "", err
+	}
+	switch outputWriter.(type) {
+	case io.WriteCloser:
+		outputWriter.(io.WriteCloser).Close()
+	}
+	return encoding != "", encoding, nil
+}
+
+// ParseEncoding will extract the right encoding for response
+// the Accept-Encoding's sec is here:
+// http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html#sec14.3
+
+func ParseEncoding(r *http.Request) string {
+	if r == nil {
+		return ""
+	}
+	return parseEncoding(r)
+}
+
+type q struct {
+	name  string
+	value float64
+}
+
+func noneCompress(wr io.Writer, level int) (io.Writer, error) {
+	return wr, nil
+}
+func gzipCompress(wr io.Writer, level int) (io.Writer, error) {
+	return gzip.NewWriterLevel(wr, level)
+}
+func deflateCompress(wr io.Writer, level int) (io.Writer, error) {
+	return flate.NewWriter(wr, level)
+}
+
+type acceptEncoder struct {
+	name   string
+	encode func(io.Writer, int) (io.Writer, error)
+}
+
+var (
+	encoderMap = map[string]acceptEncoder{ // all the other compress methods will ignore
+		"gzip":     acceptEncoder{"gzip", gzipCompress},
+		"deflate":  acceptEncoder{"deflate", deflateCompress},
+		"*":        acceptEncoder{"gzip", gzipCompress}, // * means any compress will accept,we prefer gzip
+		"identity": acceptEncoder{"", noneCompress},     // identity means none-compress
+	}
+)
+
+func parseEncoding(r *http.Request) string {
+	acceptEncoding := r.Header.Get("Accept-Encoding")
+	if acceptEncoding == "" {
+		return ""
+	}
+	var lastQ q
+	for _, v := range strings.Split(acceptEncoding, ",") {
+		v = strings.TrimSpace(v)
+		if v == "" {
+			continue
+		}
+		vs := strings.Split(v, ";")
+		if len(vs) == 1 {
+			lastQ = q{vs[0], 1}
+			break
+		}
+		if len(vs) == 2 {
+			f, _ := strconv.ParseFloat(strings.Replace(vs[1], "q=", "", -1), 64)
+			if f == 0 {
+				continue
+			}
+			if f > lastQ.value {
+				lastQ = q{vs[0], f}
+			}
+		}
+	}
+	if cf, ok := encoderMap[lastQ.name]; ok {
+		return cf.name
+	} else {
+		return ""
+	}
+}

context/acceptencoder_test.go

@@ -0,0 +1,45 @@
+// Copyright 2015 beego Author. All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package context
+
+import (
+	"net/http"
+	"testing"
+)
+
+func Test_ExtractEncoding(t *testing.T) {
+	if parseEncoding(&http.Request{Header: map[string][]string{"Accept-Encoding": []string{"gzip,deflate"}}}) != "gzip" {
+		t.Fail()
+	}
+	if parseEncoding(&http.Request{Header: map[string][]string{"Accept-Encoding": []string{"deflate,gzip"}}}) != "deflate" {
+		t.Fail()
+	}
+	if parseEncoding(&http.Request{Header: map[string][]string{"Accept-Encoding": []string{"gzip;q=.5,deflate"}}}) != "deflate" {
+		t.Fail()
+	}
+	if parseEncoding(&http.Request{Header: map[string][]string{"Accept-Encoding": []string{"gzip;q=.5,deflate;q=0.3"}}}) != "gzip" {
+		t.Fail()
+	}
+
+	if parseEncoding(&http.Request{Header: map[string][]string{"Accept-Encoding": []string{"gzip;q=0,deflate"}}}) != "deflate" {
+		t.Fail()
+	}
+	if parseEncoding(&http.Request{Header: map[string][]string{"Accept-Encoding": []string{"deflate;q=0.5,gzip;q=0.5,identity"}}}) != "" {
+		t.Fail()
+	}
+	if parseEncoding(&http.Request{Header: map[string][]string{"Accept-Encoding": []string{"*"}}}) != "gzip" {
+		t.Fail()
+	}
+}