Overview
| Comment: | Initial implementation of commands/mtf (based on commands/pdc) |
|---|---|
| Downloads: | Tarball | ZIP archive | SQL archive |
| Timelines: | family | ancestors | descendants | both | trunk |
| Files: | files | file ages | folders |
| SHA1: |
e72b637df4da3b4267e03d12fedcf6a0 |
| User & Date: | spaskalev on 2014-12-26 16:02:18 |
| Other Links: | manifest | tags |
Context
|
2014-12-26
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| 21:35 | Added 0dev.org/types, providing aliases that implement sort.Interface for [u]int{8|16|32|64} check-in: 129d90b4a8 user: spaskalev tags: trunk | |
| 16:02 | Initial implementation of commands/mtf (based on commands/pdc) check-in: e72b637df4 user: spaskalev tags: trunk | |
| 15:50 | Initial implementation of package mtf - a move-to-front transform. check-in: ad5c25d9ab user: spaskalev tags: trunk | |
Changes
Added src/0dev.org/commands/mtf/main.go version [b672c1daee].
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package main
import (
iou "0dev.org/ioutil"
mtf "0dev.org/mtf"
"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
}
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