src/cmd/gofmt/gofmt.go - go - Git at Google

 // 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"
 	"io"
 	"io/ioutil"
 	"os"
 	"os/exec"
 	"path/filepath"
 	"runtime"
 	"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()
 }

 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 {
 	var perm os.FileMode = 0644
 	if in == nil {
 		f, err := os.Open(filename)
 		if err != nil {
 			return err
 		}
 		defer f.Close()
 		fi, err := f.Stat()
 		if err != nil {
 			return err
 		}
 		in = f
 		perm = fi.Mode().Perm()
 	}

 	src, err := ioutil.ReadAll(in)
 	if err != nil {
 		return err
 	}

 	file, sourceAdj, indentAdj, err := 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)
 	}

 	ast.Inspect(file, normalizeNumbers)

 	res, err := 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 {
 			// make a temporary backup before overwriting original
 			bakname, err := backupFile(filename+".", src, perm)
 			if err != nil {
 				return err
 			}
 			err = ioutil.WriteFile(filename, res, perm)
 			if err != nil {
 				os.Rename(bakname, filename)
 				return err
 			}
 			err = os.Remove(bakname)
 			if err != nil {
 				return err
 			}
 		}
 		if *doDiff {
 			data, err := diff(src, res, filename)
 			if err != nil {
 				return fmt.Errorf("computing diff: %s", err)
 			}
 			fmt.Printf("diff -u %s %s\n", filepath.ToSlash(filename+".orig"), filepath.ToSlash(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)
 	}
 	// Don't complain if a file was deleted in the meantime (i.e.
 	// the directory changed concurrently while running gofmt).
 	if err != nil && !os.IsNotExist(err) {
 		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 writeTempFile(dir, prefix string, data []byte) (string, error) {
 	file, err := ioutil.TempFile(dir, prefix)
 	if err != nil {
 		return "", err
 	}
 	_, err = file.Write(data)
 	if err1 := file.Close(); err == nil {
 		err = err1
 	}
 	if err != nil {
 		os.Remove(file.Name())
 		return "", err
 	}
 	return file.Name(), nil
 }

 func diff(b1, b2 []byte, filename string) (data []byte, err error) {
 	f1, err := writeTempFile("", "gofmt", b1)
 	if err != nil {
 		return
 	}
 	defer os.Remove(f1)

 	f2, err := writeTempFile("", "gofmt", b2)
 	if err != nil {
 		return
 	}
 	defer os.Remove(f2)

 	cmd := "diff"
 	if runtime.GOOS == "plan9" {
 		cmd = "/bin/ape/diff"
 	}

 	data, err = exec.Command(cmd, "-u", f1, f2).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.
 		return replaceTempFilename(data, filename)
 	}
 	return
 }

 // replaceTempFilename replaces temporary filenames in diff with actual one.
 //
 // --- /tmp/gofmt316145376	2017-02-03 19:13:00.280468375 -0500
 // +++ /tmp/gofmt617882815	2017-02-03 19:13:00.280468375 -0500
 // ...
 // ->
 // --- path/to/file.go.orig	2017-02-03 19:13:00.280468375 -0500
 // +++ path/to/file.go	2017-02-03 19:13:00.280468375 -0500
 // ...
 func replaceTempFilename(diff []byte, filename string) ([]byte, error) {
 	bs := bytes.SplitN(diff, []byte{'\n'}, 3)
 	if len(bs) < 3 {
 		return nil, fmt.Errorf("got unexpected diff for %s", filename)
 	}
 	// Preserve timestamps.
 	var t0, t1 []byte
 	if i := bytes.LastIndexByte(bs[0], '\t'); i != -1 {
 		t0 = bs[0][i:]
 	}
 	if i := bytes.LastIndexByte(bs[1], '\t'); i != -1 {
 		t1 = bs[1][i:]
 	}
 	// Always print filepath with slash separator.
 	f := filepath.ToSlash(filename)
 	bs[0] = []byte(fmt.Sprintf("--- %s%s", f+".orig", t0))
 	bs[1] = []byte(fmt.Sprintf("+++ %s%s", f, t1))
 	return bytes.Join(bs, []byte{'\n'}), nil
 }

 const chmodSupported = runtime.GOOS != "windows"

 // backupFile writes data to a new file named filename<number> with permissions perm,
 // with <number randomly chosen such that the file name is unique. backupFile returns
 // the chosen file name.
 func backupFile(filename string, data []byte, perm os.FileMode) (string, error) {
 	// create backup file
 	f, err := ioutil.TempFile(filepath.Dir(filename), filepath.Base(filename))
 	if err != nil {
 		return "", err
 	}
 	bakname := f.Name()
 	if chmodSupported {
 		err = f.Chmod(perm)
 		if err != nil {
 			f.Close()
 			os.Remove(bakname)
 			return bakname, err
 		}
 	}

 	// write data to backup file
 	_, err = f.Write(data)
 	if err1 := f.Close(); err == nil {
 		err = err1
 	}

 	return bakname, err
 }

 // normalizeNumbers rewrites base prefixes and exponents to
 // use lower-case letters, and removes leading 0's from
 // integer imaginary literals. It leaves hexadecimal digits
 // alone.
 func normalizeNumbers(n ast.Node) bool {
 	lit, _ := n.(*ast.BasicLit)
 	if lit == nil || (lit.Kind != token.INT && lit.Kind != token.FLOAT && lit.Kind != token.IMAG) {
 		return true
 	}
 	if len(lit.Value) < 2 {
 		return false // only one digit (common case) - nothing to do
 	}
 	// len(lit.Value) >= 2

 	// We ignore lit.Kind because for lit.Kind == token.IMAG the literal may be an integer
 	// or floating-point value, decimal or not. Instead, just consider the literal pattern.
 	x := lit.Value
 	switch x[:2] {
 	default:
 		// 0-prefix octal, decimal int, or float (possibly with 'i' suffix)
 		if i := strings.LastIndexByte(x, 'E'); i >= 0 {
 			x = x[:i] + "e" + x[i+1:]
 			break
 		}
 		// remove leading 0's from integer (but not floating-point) imaginary literals
 		if x[len(x)-1] == 'i' && strings.IndexByte(x, '.') < 0 && strings.IndexByte(x, 'e') < 0 {
 			x = strings.TrimLeft(x, "0_")
 			if x == "i" {
 				x = "0i"
 			}
 		}
 	case "0X":
 		x = "0x" + x[2:]
 		fallthrough
 	case "0x":
 		// possibly a hexadecimal float
 		if i := strings.LastIndexByte(x, 'P'); i >= 0 {
 			x = x[:i] + "p" + x[i+1:]
 		}
 	case "0O":
 		x = "0o" + x[2:]
 	case "0o":
 		// nothing to do
 	case "0B":
 		x = "0b" + x[2:]
 	case "0b":
 		// nothing to do
 	}

 	lit.Value = x
 	return false
 }
	// 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"
	"io"
	"io/ioutil"
	"os"
	"os/exec"
	"path/filepath"
	"runtime"
	"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()
	}

	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 {
	var perm os.FileMode = 0644
	if in == nil {
	f, err := os.Open(filename)
	if err != nil {
	return err
	}
	defer f.Close()
	fi, err := f.Stat()
	if err != nil {
	return err
	}
	in = f
	perm = fi.Mode().Perm()
	}

	src, err := ioutil.ReadAll(in)
	if err != nil {
	return err
	}

	file, sourceAdj, indentAdj, err := 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)
	}

	ast.Inspect(file, normalizeNumbers)

	res, err := 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 {
	// make a temporary backup before overwriting original
	bakname, err := backupFile(filename+".", src, perm)
	if err != nil {
	return err
	}
	err = ioutil.WriteFile(filename, res, perm)
	if err != nil {
	os.Rename(bakname, filename)
	return err
	}
	err = os.Remove(bakname)
	if err != nil {
	return err
	}
	}
	if *doDiff {
	data, err := diff(src, res, filename)
	if err != nil {
	return fmt.Errorf("computing diff: %s", err)
	}
	fmt.Printf("diff -u %s %s\n", filepath.ToSlash(filename+".orig"), filepath.ToSlash(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)
	}
	// Don't complain if a file was deleted in the meantime (i.e.
	// the directory changed concurrently while running gofmt).
	if err != nil && !os.IsNotExist(err) {
	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 writeTempFile(dir, prefix string, data []byte) (string, error) {
	file, err := ioutil.TempFile(dir, prefix)
	if err != nil {
	return "", err
	}
	_, err = file.Write(data)
	if err1 := file.Close(); err == nil {
	err = err1
	}
	if err != nil {
	os.Remove(file.Name())
	return "", err
	}
	return file.Name(), nil
	}

	func diff(b1, b2 []byte, filename string) (data []byte, err error) {
	f1, err := writeTempFile("", "gofmt", b1)
	if err != nil {
	return
	}
	defer os.Remove(f1)

	f2, err := writeTempFile("", "gofmt", b2)
	if err != nil {
	return
	}
	defer os.Remove(f2)

	cmd := "diff"
	if runtime.GOOS == "plan9" {
	cmd = "/bin/ape/diff"
	}

	data, err = exec.Command(cmd, "-u", f1, f2).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.
	return replaceTempFilename(data, filename)
	}
	return
	}

	// replaceTempFilename replaces temporary filenames in diff with actual one.
	//
	// --- /tmp/gofmt316145376 2017-02-03 19:13:00.280468375 -0500
	// +++ /tmp/gofmt617882815 2017-02-03 19:13:00.280468375 -0500
	// ...
	// ->
	// --- path/to/file.go.orig 2017-02-03 19:13:00.280468375 -0500
	// +++ path/to/file.go 2017-02-03 19:13:00.280468375 -0500
	// ...
	func replaceTempFilename(diff []byte, filename string) ([]byte, error) {
	bs := bytes.SplitN(diff, []byte{'\n'}, 3)
	if len(bs) < 3 {
	return nil, fmt.Errorf("got unexpected diff for %s", filename)
	}
	// Preserve timestamps.
	var t0, t1 []byte
	if i := bytes.LastIndexByte(bs[0], '\t'); i != -1 {
	t0 = bs[0][i:]
	}
	if i := bytes.LastIndexByte(bs[1], '\t'); i != -1 {
	t1 = bs[1][i:]
	}
	// Always print filepath with slash separator.
	f := filepath.ToSlash(filename)
	bs[0] = []byte(fmt.Sprintf("--- %s%s", f+".orig", t0))
	bs[1] = []byte(fmt.Sprintf("+++ %s%s", f, t1))
	return bytes.Join(bs, []byte{'\n'}), nil
	}

	const chmodSupported = runtime.GOOS != "windows"

	// backupFile writes data to a new file named filename<number> with permissions perm,
	// with <number randomly chosen such that the file name is unique. backupFile returns
	// the chosen file name.
	func backupFile(filename string, data []byte, perm os.FileMode) (string, error) {
	// create backup file
	f, err := ioutil.TempFile(filepath.Dir(filename), filepath.Base(filename))
	if err != nil {
	return "", err
	}
	bakname := f.Name()
	if chmodSupported {
	err = f.Chmod(perm)
	if err != nil {
	f.Close()
	os.Remove(bakname)
	return bakname, err
	}
	}

	// write data to backup file
	_, err = f.Write(data)
	if err1 := f.Close(); err == nil {
	err = err1
	}

	return bakname, err
	}

	// normalizeNumbers rewrites base prefixes and exponents to
	// use lower-case letters, and removes leading 0's from
	// integer imaginary literals. It leaves hexadecimal digits
	// alone.
	func normalizeNumbers(n ast.Node) bool {
	lit, _ := n.(*ast.BasicLit)
	if lit == nil \|\| (lit.Kind != token.INT && lit.Kind != token.FLOAT && lit.Kind != token.IMAG) {
	return true
	}
	if len(lit.Value) < 2 {
	return false // only one digit (common case) - nothing to do
	}
	// len(lit.Value) >= 2

	// We ignore lit.Kind because for lit.Kind == token.IMAG the literal may be an integer
	// or floating-point value, decimal or not. Instead, just consider the literal pattern.
	x := lit.Value
	switch x[:2] {
	default:
	// 0-prefix octal, decimal int, or float (possibly with 'i' suffix)
	if i := strings.LastIndexByte(x, 'E'); i >= 0 {
	x = x[:i] + "e" + x[i+1:]
	break
	}
	// remove leading 0's from integer (but not floating-point) imaginary literals
	if x[len(x)-1] == 'i' && strings.IndexByte(x, '.') < 0 && strings.IndexByte(x, 'e') < 0 {
	x = strings.TrimLeft(x, "0_")
	if x == "i" {
	x = "0i"
	}
	}
	case "0X":
	x = "0x" + x[2:]
	fallthrough
	case "0x":
	// possibly a hexadecimal float
	if i := strings.LastIndexByte(x, 'P'); i >= 0 {
	x = x[:i] + "p" + x[i+1:]
	}
	case "0O":
	x = "0o" + x[2:]
	case "0o":
	// nothing to do
	case "0B":
	x = "0b" + x[2:]
	case "0b":
	// nothing to do
	}

	lit.Value = x
	return false
	}