/
unfold.go
76 lines (73 loc) · 2.12 KB
/
unfold.go
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// 2019, Georg Sauthoff <mail@gms.tf>
// SPDX-License-Identifier: GPL-3.0-or-later
package main
import (
"bytes"
"io"
)
type unfold_writer struct {
out io.WriteCloser
state int
}
func new_unfold_writer(out io.WriteCloser) *unfold_writer {
w := new(unfold_writer)
w.out = out
return w
}
func (w *unfold_writer) Close() error {
newline := []byte("\n")
if _, err := w.out.Write(newline); err != nil {
return err
}
return w.out.Close()
}
func (w *unfold_writer) Write(block []byte) (int, error) {
const ( OUTSIDE = iota
IN_FOLD
)
n := len(block)
newline := []byte("\n")
for len(block) != 0 {
switch w.state {
case OUTSIDE:
i := bytes.IndexByte(block, byte('\n'))
if i == -1 {
if _, err := w.out.Write(block); err != nil {
return 0, err
}
block = block[:0]
} else {
if i+1 < len(block) {
if block[i+1] == byte(' ') || block[i+1] == byte('\t') {
if _, err := w.out.Write(block[:i]); err != nil {
return 0, err
}
block = block[i+2:]
} else {
if _, err := w.out.Write(block[:i+1]); err != nil {
return 0, err
}
block = block[i+1:]
}
} else {
if _, err := w.out.Write(block[:i]); err != nil {
return 0, err
}
block = block[i+1:]
w.state = IN_FOLD
}
}
case IN_FOLD:
if block[0] == byte(' ') || block[0] == byte('\t') {
//w.out.Write(block[:1])
block = block[1:]
} else {
if _, err := w.out.Write(newline); err != nil {
return 0, err
}
}
w.state = OUTSIDE
}
}
return n, nil
}