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package archiver
import (
"fmt"
"io"
"path/filepath"
"github.com/pierrec/lz4"
)
// Lz4 facilitates LZ4 compression.
type Lz4 struct {
CompressionLevel int
}
// Compress reads in, compresses it, and writes it to out.
func (lz *Lz4) Compress(in io.Reader, out io.Writer) error {
w := lz4.NewWriter(out)
w.Header.CompressionLevel = lz.CompressionLevel
defer w.Close()
_, err := io.Copy(w, in)
return err
}
// Decompress reads in, decompresses it, and writes it to out.
func (lz *Lz4) Decompress(in io.Reader, out io.Writer) error {
r := lz4.NewReader(in)
_, err := io.Copy(out, r)
return err
}
// CheckExt ensures the file extension matches the format.
func (lz *Lz4) CheckExt(filename string) error {
if filepath.Ext(filename) != ".lz4" {
return fmt.Errorf("filename must have a .lz4 extension")
}
return nil
}
func (lz *Lz4) String() string { return "lz4" }
// NewLz4 returns a new, default instance ready to be customized and used.
func NewLz4() *Lz4 {
return &Lz4{
CompressionLevel: 9, // https://github.com/lz4/lz4/blob/1b819bfd633ae285df2dfe1b0589e1ec064f2873/lib/lz4hc.h#L48
}
}
// Compile-time checks to ensure type implements desired interfaces.
var (
_ = Compressor(new(Lz4))
_ = Decompressor(new(Lz4))
)
// DefaultLz4 is a default instance that is conveniently ready to use.
var DefaultLz4 = NewLz4()
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