blob: 0bc385b5b56072a6c919df20f314f0b285e20f7d [file] [log] [blame]
// 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()
}