123 lines
2.6 KiB
Go
123 lines
2.6 KiB
Go
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package internal
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import (
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"bytes"
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"compress/gzip"
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"errors"
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"io"
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)
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// NewContentEncoder returns a ContentEncoder for the encoding type.
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func NewContentEncoder(encoding string) (ContentEncoder, error) {
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switch encoding {
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case "gzip":
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return NewGzipEncoder()
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case "identity", "":
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return NewIdentityEncoder(), nil
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default:
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return nil, errors.New("invalid value for content_encoding")
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}
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}
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// NewContentDecoder returns a ContentDecoder for the encoding type.
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func NewContentDecoder(encoding string) (ContentDecoder, error) {
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switch encoding {
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case "gzip":
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return NewGzipDecoder()
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case "identity", "":
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return NewIdentityDecoder(), nil
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default:
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return nil, errors.New("invalid value for content_encoding")
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}
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}
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// ContentEncoder applies a wrapper encoding to byte buffers.
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type ContentEncoder interface {
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Encode([]byte) ([]byte, error)
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}
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// GzipEncoder compresses the buffer using gzip at the default level.
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type GzipEncoder struct {
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writer *gzip.Writer
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buf *bytes.Buffer
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}
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func NewGzipEncoder() (*GzipEncoder, error) {
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var buf bytes.Buffer
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return &GzipEncoder{
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writer: gzip.NewWriter(&buf),
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buf: &buf,
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}, nil
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}
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func (e *GzipEncoder) Encode(data []byte) ([]byte, error) {
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e.buf.Reset()
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e.writer.Reset(e.buf)
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_, err := e.writer.Write(data)
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if err != nil {
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return nil, err
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}
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err = e.writer.Close()
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if err != nil {
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return nil, err
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}
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return e.buf.Bytes(), nil
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}
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// IdentityEncoder is a null encoder that applies no transformation.
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type IdentityEncoder struct{}
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func NewIdentityEncoder() *IdentityEncoder {
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return &IdentityEncoder{}
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}
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func (*IdentityEncoder) Encode(data []byte) ([]byte, error) {
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return data, nil
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}
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// ContentDecoder removes a wrapper encoding from byte buffers.
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type ContentDecoder interface {
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Decode([]byte) ([]byte, error)
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}
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// GzipDecoder decompresses buffers with gzip compression.
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type GzipDecoder struct {
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reader *gzip.Reader
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buf *bytes.Buffer
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}
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func NewGzipDecoder() (*GzipDecoder, error) {
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return &GzipDecoder{
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reader: new(gzip.Reader),
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buf: new(bytes.Buffer),
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}, nil
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}
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func (d *GzipDecoder) Decode(data []byte) ([]byte, error) {
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d.reader.Reset(bytes.NewBuffer(data))
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d.buf.Reset()
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_, err := d.buf.ReadFrom(d.reader)
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if err != nil && err != io.EOF {
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return nil, err
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}
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err = d.reader.Close()
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if err != nil {
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return nil, err
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}
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return d.buf.Bytes(), nil
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}
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// IdentityDecoder is a null decoder that returns the input.
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type IdentityDecoder struct{}
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func NewIdentityDecoder() *IdentityDecoder {
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return &IdentityDecoder{}
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}
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func (*IdentityDecoder) Decode(data []byte) ([]byte, error) {
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return data, nil
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}
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