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// Licensed to the Apache Software Foundation (ASF) under one
// or more contributor license agreements. See the NOTICE file
// distributed with this work for additional information
// regarding copyright ownership. The ASF licenses this file
// to you 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 compress
import (
"bytes"
"io"
"github.com/andybalholm/brotli"
"github.com/apache/arrow/go/v13/parquet/internal/debug"
)
type brotliCodec struct{}
func (brotliCodec) NewReader(r io.Reader) io.ReadCloser {
return io.NopCloser(brotli.NewReader(r))
}
func (b brotliCodec) EncodeLevel(dst, src []byte, level int) []byte {
if level == DefaultCompressionLevel {
level = brotli.DefaultCompression
}
maxlen := int(b.CompressBound(int64(len(src))))
if dst == nil || cap(dst) < maxlen {
dst = make([]byte, 0, maxlen)
}
buf := bytes.NewBuffer(dst[:0])
w := brotli.NewWriterLevel(buf, level)
_, err := w.Write(src)
if err != nil {
panic(err)
}
if err := w.Close(); err != nil {
panic(err)
}
return buf.Bytes()
}
func (b brotliCodec) Encode(dst, src []byte) []byte {
return b.EncodeLevel(dst, src, brotli.DefaultCompression)
}
func (brotliCodec) Decode(dst, src []byte) []byte {
rdr := brotli.NewReader(bytes.NewReader(src))
if dst != nil {
var (
sofar = 0
n = -1
err error = nil
)
for n != 0 && err == nil {
n, err = rdr.Read(dst[sofar:])
sofar += n
}
if err != nil && err != io.EOF {
panic(err)
}
return dst[:sofar]
}
dst, err := io.ReadAll(rdr)
if err != nil {
panic(err)
}
return dst
}
// taken from brotli/enc/encode.c:1426
// BrotliEncoderMaxCompressedSize
func (brotliCodec) CompressBound(len int64) int64 {
// [window bits / empty metadata] + N * [uncompressed] + [last empty]
debug.Assert(len > 0, "brotli compressbound should be > 0")
nlarge := len >> 14
overhead := 2 + (4 * nlarge) + 3 + 1
result := len + overhead
if len == 0 {
return 2
}
if result < len {
return 0
}
return len
}
func (brotliCodec) NewWriter(w io.Writer) io.WriteCloser {
return brotli.NewWriter(w)
}
func (brotliCodec) NewWriterLevel(w io.Writer, level int) (io.WriteCloser, error) {
if level == DefaultCompressionLevel {
level = brotli.DefaultCompression
}
return brotli.NewWriterLevel(w, level), nil
}
func init() {
codecs[Codecs.Brotli] = brotliCodec{}
}
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