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/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, "print all (including spurious) errors")

 	// layout control
 	comments  = flag.Bool("comments", true, "print comments")
 	tabWidth  = flag.Int("tabwidth", 8, "tab width")
 	tabIndent = flag.Bool("tabs", true, "indent with tabs")

 	// debugging
 	cpuprofile = flag.String("cpuprofile", "", "write cpu profile to this file")
 )

 var (
 	fileSet     = token.NewFileSet() // per process FileSet
 	exitCode    = 0
 	rewrite     func(*ast.File) *ast.File
 	parserMode  parser.Mode
 	printerMode printer.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.Mode(0)
 	if *comments {
 		parserMode |= parser.ParseComments
 	}
 	if *allErrors {
 		parserMode |= parser.SpuriousErrors
 	}
 }

 func initPrinterMode() {
 	printerMode = printer.UseSpaces
 	if *tabIndent {
 		printerMode |= printer.TabIndent
 	}
 }

 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, adjust, err := parse(fileSet, filename, src, stdin)
 	if err != nil {
 		return err
 	}

 	if rewrite != nil {
 		if adjust == nil {
 			file = rewrite(file)
 		} else {
 			fmt.Fprintf(os.Stderr, "warning: rewrite ignored for incomplete programs\n")
 		}
 	}

 	ast.SortImports(fileSet, file)

 	if *simplifyAST {
 		simplify(file)
 	}

 	var buf bytes.Buffer
 	err = (&printer.Config{Mode: printerMode, Tabwidth: *tabWidth}).Fprint(&buf, fileSet, file)
 	if err != nil {
 		return err
 	}
 	res := buf.Bytes()
 	if adjust != nil {
 		res = adjust(src, res)
 	}

 	if !bytes.Equal(src, res) {
 		// formatting has changed
 		if *list {
 			fmt.Fprintln(out, filename)
 		}
 		if *write {
 			err = ioutil.WriteFile(filename, res, 0)
 			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 *tabWidth < 0 {
 		fmt.Fprintf(os.Stderr, "negative tabwidth %d\n", *tabWidth)
 		exitCode = 2
 		return
 	}

 	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()
 	initPrinterMode()
 	initRewrite()

 	if flag.NArg() == 0 {
 		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

 }

 // parse parses src, which was read from filename,
 // as a Go source file or statement list.
 func parse(fset *token.FileSet, filename string, src []byte, stdin bool) (*ast.File, func(orig, src []byte) []byte, error) {
 	// Try as whole source file.
 	file, err := parser.ParseFile(fset, filename, src, parserMode)
 	if err == nil {
 		return file, nil, nil
 	}
 	// If the error is that the source file didn't begin with a
 	// package line and this is standard input, fall through to
 	// try as a source fragment.  Stop and return on any other error.
 	if !stdin || !strings.Contains(err.Error(), "expected 'package'") {
 		return nil, nil, err
 	}

 	// If this is a declaration list, make it a source file
 	// by inserting a package clause.
 	// Insert using a ;, not a newline, so that the line numbers
 	// in psrc match the ones in src.
 	psrc := append([]byte("package p;"), src...)
 	file, err = parser.ParseFile(fset, filename, psrc, parserMode)
 	if err == nil {
 		adjust := func(orig, src []byte) []byte {
 			// Remove the package clause.
 			// Gofmt has turned the ; into a \n.
 			src = src[len("package p\n"):]
 			return matchSpace(orig, src)
 		}
 		return file, adjust, nil
 	}
 	// If the error is that the source file didn't begin with a
 	// declaration, fall through to try as a statement list.
 	// Stop and return on any other error.
 	if !strings.Contains(err.Error(), "expected declaration") {
 		return nil, nil, err
 	}

 	// If this is a statement list, make it a source file
 	// by inserting a package clause and turning the list
 	// into a function body.  This handles expressions too.
 	// Insert using a ;, not a newline, so that the line numbers
 	// in fsrc match the ones in src.
 	fsrc := append(append([]byte("package p; func _() {"), src...), '}')
 	file, err = parser.ParseFile(fset, filename, fsrc, parserMode)
 	if err == nil {
 		adjust := func(orig, src []byte) []byte {
 			// Remove the wrapping.
 			// Gofmt has turned the ; into a \n\n.
 			src = src[len("package p\n\nfunc _() {"):]
 			src = src[:len(src)-len("}\n")]
 			// Gofmt has also indented the function body one level.
 			// Remove that indent.
 			src = bytes.Replace(src, []byte("\n\t"), []byte("\n"), -1)
 			return matchSpace(orig, src)
 		}
 		return file, adjust, nil
 	}

 	// Failed, and out of options.
 	return nil, nil, err
 }

 func cutSpace(b []byte) (before, middle, after []byte) {
 	i := 0
 	for i < len(b) && (b[i] == ' ' || b[i] == '\t' || b[i] == '\n') {
 		i++
 	}
 	j := len(b)
 	for j > 0 && (b[j-1] == ' ' || b[j-1] == '\t' || b[j-1] == '\n') {
 		j--
 	}
 	if i <= j {
 		return b[:i], b[i:j], b[j:]
 	}
 	return nil, nil, b[j:]
 }

 // matchSpace reformats src to use the same space context as orig.
 // 1) If orig begins with blank lines, matchSpace inserts them at the beginning of src.
 // 2) matchSpace copies the indentation of the first non-blank line in orig
 //    to every non-blank line in src.
 // 3) matchSpace copies the trailing space from orig and uses it in place
 //   of src's trailing space.
 func matchSpace(orig []byte, src []byte) []byte {
 	before, _, after := cutSpace(orig)
 	i := bytes.LastIndex(before, []byte{'\n'})
 	before, indent := before[:i+1], before[i+1:]

 	_, src, _ = cutSpace(src)

 	var b bytes.Buffer
 	b.Write(before)
 	for len(src) > 0 {
 		line := src
 		if i := bytes.IndexByte(line, '\n'); i >= 0 {
 			line, src = line[:i+1], line[i+1:]
 		} else {
 			src = nil
 		}
 		if len(line) > 0 && line[0] != '\n' { // not blank
 			b.Write(indent)
 		}
 		b.Write(line)
 	}
 	b.Write(after)
 	return b.Bytes()
 }
	// 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/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, "print all (including spurious) errors")

	// layout control
	comments = flag.Bool("comments", true, "print comments")
	tabWidth = flag.Int("tabwidth", 8, "tab width")
	tabIndent = flag.Bool("tabs", true, "indent with tabs")

	// debugging
	cpuprofile = flag.String("cpuprofile", "", "write cpu profile to this file")
	)

	var (
	fileSet = token.NewFileSet() // per process FileSet
	exitCode = 0
	rewrite func(ast.File) ast.File
	parserMode parser.Mode
	printerMode printer.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.Mode(0)
	if *comments {
	parserMode \|= parser.ParseComments
	}
	if *allErrors {
	parserMode \|= parser.SpuriousErrors
	}
	}

	func initPrinterMode() {
	printerMode = printer.UseSpaces
	if *tabIndent {
	printerMode \|= printer.TabIndent
	}
	}

	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, adjust, err := parse(fileSet, filename, src, stdin)
	if err != nil {
	return err
	}

	if rewrite != nil {
	if adjust == nil {
	file = rewrite(file)
	} else {
	fmt.Fprintf(os.Stderr, "warning: rewrite ignored for incomplete programs\n")
	}
	}

	ast.SortImports(fileSet, file)

	if *simplifyAST {
	simplify(file)
	}

	var buf bytes.Buffer
	err = (&printer.Config{Mode: printerMode, Tabwidth: *tabWidth}).Fprint(&buf, fileSet, file)
	if err != nil {
	return err
	}
	res := buf.Bytes()
	if adjust != nil {
	res = adjust(src, res)
	}

	if !bytes.Equal(src, res) {
	// formatting has changed
	if *list {
	fmt.Fprintln(out, filename)
	}
	if *write {
	err = ioutil.WriteFile(filename, res, 0)
	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 *tabWidth < 0 {
	fmt.Fprintf(os.Stderr, "negative tabwidth %d\n", *tabWidth)
	exitCode = 2
	return
	}

	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()
	initPrinterMode()
	initRewrite()

	if flag.NArg() == 0 {
	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

	}

	// parse parses src, which was read from filename,
	// as a Go source file or statement list.
	func parse(fset token.FileSet, filename string, src []byte, stdin bool) (ast.File, func(orig, src []byte) []byte, error) {
	// Try as whole source file.
	file, err := parser.ParseFile(fset, filename, src, parserMode)
	if err == nil {
	return file, nil, nil
	}
	// If the error is that the source file didn't begin with a
	// package line and this is standard input, fall through to
	// try as a source fragment. Stop and return on any other error.
	if !stdin \|\| !strings.Contains(err.Error(), "expected 'package'") {
	return nil, nil, err
	}

	// If this is a declaration list, make it a source file
	// by inserting a package clause.
	// Insert using a ;, not a newline, so that the line numbers
	// in psrc match the ones in src.
	psrc := append([]byte("package p;"), src...)
	file, err = parser.ParseFile(fset, filename, psrc, parserMode)
	if err == nil {
	adjust := func(orig, src []byte) []byte {
	// Remove the package clause.
	// Gofmt has turned the ; into a \n.
	src = src[len("package p\n"):]
	return matchSpace(orig, src)
	}
	return file, adjust, nil
	}
	// If the error is that the source file didn't begin with a
	// declaration, fall through to try as a statement list.
	// Stop and return on any other error.
	if !strings.Contains(err.Error(), "expected declaration") {
	return nil, nil, err
	}

	// If this is a statement list, make it a source file
	// by inserting a package clause and turning the list
	// into a function body. This handles expressions too.
	// Insert using a ;, not a newline, so that the line numbers
	// in fsrc match the ones in src.
	fsrc := append(append([]byte("package p; func _() {"), src...), '}')
	file, err = parser.ParseFile(fset, filename, fsrc, parserMode)
	if err == nil {
	adjust := func(orig, src []byte) []byte {
	// Remove the wrapping.
	// Gofmt has turned the ; into a \n\n.
	src = src[len("package p\n\nfunc _() {"):]
	src = src[:len(src)-len("}\n")]
	// Gofmt has also indented the function body one level.
	// Remove that indent.
	src = bytes.Replace(src, []byte("\n\t"), []byte("\n"), -1)
	return matchSpace(orig, src)
	}
	return file, adjust, nil
	}

	// Failed, and out of options.
	return nil, nil, err
	}

	func cutSpace(b []byte) (before, middle, after []byte) {
	i := 0
	for i < len(b) && (b[i] == ' ' \|\| b[i] == '\t' \|\| b[i] == '\n') {
	i++
	}
	j := len(b)
	for j > 0 && (b[j-1] == ' ' \|\| b[j-1] == '\t' \|\| b[j-1] == '\n') {
	j--
	}
	if i <= j {
	return b[:i], b[i:j], b[j:]
	}
	return nil, nil, b[j:]
	}

	// matchSpace reformats src to use the same space context as orig.
	// 1) If orig begins with blank lines, matchSpace inserts them at the beginning of src.
	// 2) matchSpace copies the indentation of the first non-blank line in orig
	// to every non-blank line in src.
	// 3) matchSpace copies the trailing space from orig and uses it in place
	// of src's trailing space.
	func matchSpace(orig []byte, src []byte) []byte {
	before, _, after := cutSpace(orig)
	i := bytes.LastIndex(before, []byte{'\n'})
	before, indent := before[:i+1], before[i+1:]

	_, src, _ = cutSpace(src)

	var b bytes.Buffer
	b.Write(before)
	for len(src) > 0 {
	line := src
	if i := bytes.IndexByte(line, '\n'); i >= 0 {
	line, src = line[:i+1], line[i+1:]
	} else {
	src = nil
	}
	if len(line) > 0 && line[0] != '\n' { // not blank
	b.Write(indent)
	}
	b.Write(line)
	}
	b.Write(after)
	return b.Bytes()
	}