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214package main
import (
"bufio"
"bytes"
"fmt"
"io"
"io/ioutil"
"os"
"os/exec"
"regexp"
"strconv"
"unicode/utf8"
"9fans.net/go/acme"
)
func doApply(win *acme.Win, origBody, newBody []byte) error {
bodyFile, err := ioutil.TempFile("", "")
if err != nil {
return err
}
defer os.Remove(bodyFile.Name())
defer bodyFile.Close()
if _, err := bodyFile.Write(origBody); err != nil {
return err
}
bodyFile.Seek(0, 0)
cmd := exec.Command("diff", bodyFile.Name(), "-")
cmd.Stdin = bytes.NewReader(newBody)
cmd.Stderr = os.Stderr
diffOut, err := cmd.StdoutPipe()
if err != nil {
return err
}
if err := cmd.Start(); err != nil {
return fmt.Errorf("cannot start diff: %v", err)
}
// TODO this doesn't appear to have the desired effect -
// changes made after "nomark" don't seem to be undoable.
// if _, err := win.Write("ctl", []byte("nomark")); err != nil {
// return err
// }
// defer win.Write("ctl", []byte("mark"))
err = apply(diffOut, func(addr string, data []byte) error {
if _, err := win.Write("addr", []byte(addr)); err != nil {
return fmt.Errorf("cannot set address %q: %v", addr, err)
}
if err := writeData(win, data); err != nil {
return fmt.Errorf("cannot write data: %v", err)
}
return nil
})
if err != nil {
return err
}
return nil
}
func writeData(win *acme.Win, data []byte) error {
if len(data) == 0 {
_, err := win.Write("data", nil)
return err
}
for len(data) > 0 {
d := data
if len(d) > 8000 {
d = trimIncompleteRune(d[0:8000])
}
n, err := win.Write("data", d)
if err != nil {
return err
}
data = data[n:]
}
return nil
}
// trimIncompleteRune returns b with any trailing
// incomplete rune sliced off.
func trimIncompleteRune(b []byte) []byte {
i := len(b) - utf8.UTFMax
if i < 0 {
i = 0
}
lastStart := len(b)
for ; i < len(b); i++ {
if r, n := utf8.DecodeRune(b[i:]); r != utf8.RuneError || n > 1 {
lastStart = len(b)
continue
}
if utf8.RuneStart(b[i]) {
lastStart = i
}
}
return b[0:lastStart]
}
func quote(s string) string {
s = strconv.Quote(s)
return s[1 : len(s)-1]
}
var cmdPat = regexp.MustCompile(`^([0-9]+)(,([0-9]+))?([acd])([0-9]+)(,([0-9]+))?$`)
type diffOp struct {
n1, n2, n3, n4 int
op rune
}
func apply(diffOut io.Reader, edit func(addr string, data []byte) error) error {
scan := bufio.NewScanner(diffOut)
var buf []byte
offset := 0
for scan.Scan() {
op, err := parseDiffOp(scan.Text())
if err != nil {
return err
}
if op.op == 'c' || op.op == 'd' {
if err := eatLines(scan, "< ", op.n2-op.n1+1); err != nil {
return err
}
}
if op.op == 'c' {
if err := eatLines(scan, "---", 1); err != nil {
return err
}
}
buf = buf[:0]
if op.op != 'd' {
for i := op.n3; i <= op.n4; i++ {
if !scan.Scan() {
return io.ErrUnexpectedEOF
}
line := scan.Bytes()
if !bytes.HasPrefix(line, []byte("> ")) {
return fmt.Errorf("expected line starting with '> ', got %q", line)
}
buf = append(buf, line[2:]...)
buf = append(buf, '\n')
}
}
var addr string
if op.n1 == op.n2 {
addr = fmt.Sprintf("%d", op.n1+offset)
if op.op == 'a' {
addr += "+#0"
}
} else {
addr = fmt.Sprintf("%d,%d", op.n1+offset, op.n2+offset)
if op.op == 'a' {
return fmt.Errorf("append with multiple line source")
}
}
if err := edit(addr, buf); err != nil {
return err
}
switch op.op {
case 'a':
offset += op.n4 - op.n3 + 1
case 'd':
offset -= op.n2 - op.n1 + 1
case 'c':
offset += (op.n4 - op.n3 + 1) - (op.n2 - op.n1 + 1)
}
}
return nil
}
func eatLines(scan *bufio.Scanner, prefix string, n int) error {
bprefix := []byte(prefix)
for i := 0; i < n; i++ {
if !scan.Scan() {
return io.ErrUnexpectedEOF
}
if !bytes.HasPrefix(scan.Bytes(), bprefix) {
return fmt.Errorf("line %q does not have expected prefix %q", scan.Bytes(), bprefix)
}
}
return nil
}
func parseDiffOp(cmd string) (diffOp, error) {
var op diffOp
r := cmdPat.FindStringSubmatch(cmd)
if len(r) == 0 {
return op, fmt.Errorf("%q is not a valid diff operation", cmd)
}
op.n1 = atoi(r[1])
if r[3] != "" {
op.n2 = atoi(r[3])
} else {
op.n2 = op.n1
}
op.op = rune(r[4][0])
op.n3 = atoi(r[5])
if r[7] != "" {
op.n4 = atoi(r[7])
} else {
op.n4 = op.n3
}
return op, nil
}
func atoi(s string) int {
n, err := strconv.Atoi(s)
if err != nil {
panic(fmt.Errorf("unexpected bad number %q", s))
}
return n
}