File size: 971 Bytes
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package main
import (
"bytes"
"io"
)
type prefixer struct {
prefix string
out io.Writer
buf []byte
}
func NewPrefixer(out io.Writer, prefix string) io.Writer {
return &prefixer{
out: out,
prefix: prefix,
}
}
func (w *prefixer) writePrefix() error {
_, err := io.WriteString(w.out, w.prefix+" | ")
return err
}
func (w *prefixer) Write(p []byte) (int, error) {
var n int
for {
l := bytes.IndexByte(p, '\n')
if l == -1 {
w.buf = append(w.buf, p...)
return n + len(p), nil
}
w.buf = append(w.buf, p[:l+1]...)
n += l + 1
err := w.writePrefix()
if err != nil {
return n, err
}
// replace yarn escape sequences
w.buf = bytes.ReplaceAll(w.buf, []byte("\x1b[2K"), nil)
w.buf = bytes.ReplaceAll(w.buf, []byte("\x1b[1G"), nil)
_, err = w.out.Write(w.buf)
if err != nil {
return n, err
}
w.buf = w.buf[:0]
_, err = w.out.Write([]byte("\x1b[0m"))
if err != nil {
return n, err
}
p = p[l+1:]
}
}
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