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// Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package main
import (
"bytes"
"flag"
"fmt"
"go/ast"
"go/parser"
"go/printer"
"go/scanner"
"go/token"
"internal/format"
"io"
"io/ioutil"
"os"
"os/exec"
"path/filepath"
"runtime/pprof"
"strings"
)
var (
// main operation modes
list = flag.Bool("l", false, "list files whose formatting differs from gofmt's")
write = flag.Bool("w", false, "write result to (source) file instead of stdout")
rewriteRule = flag.String("r", "", "rewrite rule (e.g., 'a[b:len(a)] -> a[b:]')")
simplifyAST = flag.Bool("s", false, "simplify code")
doDiff = flag.Bool("d", false, "display diffs instead of rewriting files")
allErrors = flag.Bool("e", false, "report all errors (not just the first 10 on different lines)")
// debugging
cpuprofile = flag.String("cpuprofile", "", "write cpu profile to this file")
)
const (
tabWidth = 8
printerMode = printer.UseSpaces | printer.TabIndent
)
var (
fileSet = token.NewFileSet() // per process FileSet
exitCode = 0
rewrite func(*ast.File) *ast.File
parserMode parser.Mode
)
func report(err error) {
scanner.PrintError(os.Stderr, err)
exitCode = 2
}
func usage() {
fmt.Fprintf(os.Stderr, "usage: gofmt [flags] [path ...]\n")
flag.PrintDefaults()
os.Exit(2)
}
func initParserMode() {
parserMode = parser.ParseComments
if *allErrors {
parserMode |= parser.AllErrors
}
}
func isGoFile(f os.FileInfo) bool {
// ignore non-Go files
name := f.Name()
return !f.IsDir() && !strings.HasPrefix(name, ".") && strings.HasSuffix(name, ".go")
}
// If in == nil, the source is the contents of the file with the given filename.
func processFile(filename string, in io.Reader, out io.Writer, stdin bool) error {
if in == nil {
f, err := os.Open(filename)
if err != nil {
return err
}
defer f.Close()
in = f
}
src, err := ioutil.ReadAll(in)
if err != nil {
return err
}
file, sourceAdj, indentAdj, err := format.Parse(fileSet, filename, src, stdin)
if err != nil {
return err
}
if rewrite != nil {
if sourceAdj == nil {
file = rewrite(file)
} else {
fmt.Fprintf(os.Stderr, "warning: rewrite ignored for incomplete programs\n")
}
}
ast.SortImports(fileSet, file)
if *simplifyAST {
simplify(file)
}
res, err := format.Format(fileSet, file, sourceAdj, indentAdj, src, printer.Config{Mode: printerMode, Tabwidth: tabWidth})
if err != nil {
return err
}
if !bytes.Equal(src, res) {
// formatting has changed
if *list {
fmt.Fprintln(out, filename)
}
if *write {
err = ioutil.WriteFile(filename, res, 0644)
if err != nil {
return err
}
}
if *doDiff {
data, err := diff(src, res)
if err != nil {
return fmt.Errorf("computing diff: %s", err)
}
fmt.Printf("diff %s gofmt/%s\n", filename, filename)
out.Write(data)
}
}
if !*list && !*write && !*doDiff {
_, err = out.Write(res)
}
return err
}
func visitFile(path string, f os.FileInfo, err error) error {
if err == nil && isGoFile(f) {
err = processFile(path, nil, os.Stdout, false)
}
if err != nil {
report(err)
}
return nil
}
func walkDir(path string) {
filepath.Walk(path, visitFile)
}
func main() {
// call gofmtMain in a separate function
// so that it can use defer and have them
// run before the exit.
gofmtMain()
os.Exit(exitCode)
}
func gofmtMain() {
flag.Usage = usage
flag.Parse()
if *cpuprofile != "" {
f, err := os.Create(*cpuprofile)
if err != nil {
fmt.Fprintf(os.Stderr, "creating cpu profile: %s\n", err)
exitCode = 2
return
}
defer f.Close()
pprof.StartCPUProfile(f)
defer pprof.StopCPUProfile()
}
initParserMode()
initRewrite()
if flag.NArg() == 0 {
if *write {
fmt.Fprintln(os.Stderr, "error: cannot use -w with standard input")
exitCode = 2
return
}
if err := processFile("<standard input>", os.Stdin, os.Stdout, true); err != nil {
report(err)
}
return
}
for i := 0; i < flag.NArg(); i++ {
path := flag.Arg(i)
switch dir, err := os.Stat(path); {
case err != nil:
report(err)
case dir.IsDir():
walkDir(path)
default:
if err := processFile(path, nil, os.Stdout, false); err != nil {
report(err)
}
}
}
}
func diff(b1, b2 []byte) (data []byte, err error) {
f1, err := ioutil.TempFile("", "gofmt")
if err != nil {
return
}
defer os.Remove(f1.Name())
defer f1.Close()
f2, err := ioutil.TempFile("", "gofmt")
if err != nil {
return
}
defer os.Remove(f2.Name())
defer f2.Close()
f1.Write(b1)
f2.Write(b2)
data, err = exec.Command("diff", "-u", f1.Name(), f2.Name()).CombinedOutput()
if len(data) > 0 {
// diff exits with a non-zero status when the files don't match.
// Ignore that failure as long as we get output.
err = nil
}
return
}
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