package main
import (
mtf "0dev.org/encoding/mtf"
iou "0dev.org/ioutil"
"fmt"
"io"
"os"
)
func main() {
var code int
switch {
case len(os.Args) == 1:
code = transform(os.Stdout, os.Stdin)
case len(os.Args) == 2 && os.Args[1] == "-d":
code = reverse(os.Stdout, os.Stdin)
default:
fmt.Fprintln(os.Stdout, "Usage: mtf [-d]")
}
os.Exit(code)
}
// Transforms the data according to the move-to-front algorithm
// I/O is buffered for better performance
func transform(output io.Writer, input io.Reader) int {
var (
err error
buffer io.Writer = iou.SizedWriter(output, 4096)
encoder io.Writer = mtf.Encoder(buffer)
)
_, err = io.Copy(encoder, input)
if err != nil {
fmt.Fprintln(os.Stderr, "Error while encoding.\n", err)
return 1
}
// Flush the buffer
_, err = buffer.Write(nil)
if err != nil {
fmt.Fprintln(os.Stderr, "Error while flushing output buffer.\n", err)
return 1
}
return 0
}
// Reverses MTF`ed data and writes back the original bytes
// I/O is buffered for better performance
func reverse(output io.Writer, input io.Reader) int {
var (
err error
decoder io.Reader = mtf.Decoder(iou.SizedReader(input, 4096))
)
_, err = io.Copy(output, decoder)
if err != nil {
fmt.Fprintln(os.Stderr, "Error while decoding.\n", err)
return 1
}
return 0
}