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mirror of https://github.com/golang/go synced 2024-11-26 16:57:14 -07:00

go/format: Package format implements standard formatting of Go source.

Package format is a utility package that takes care of
parsing, sorting of imports, and formatting of .go source
using the canonical gofmt formatting parameters.

Use go/format in various clients instead of the lower-level components.

R=r, bradfitz, dave, rogpeppe, rsc
CC=golang-dev
https://golang.org/cl/6852075
This commit is contained in:
Robert Griesemer 2012-11-27 10:29:49 -08:00
parent 51b8edcb37
commit e781b20ac9
6 changed files with 338 additions and 52 deletions

View File

@ -9,8 +9,8 @@ import (
"flag"
"fmt"
"go/ast"
"go/format"
"go/parser"
"go/printer"
"go/scanner"
"go/token"
"io/ioutil"
@ -97,23 +97,11 @@ func main() {
os.Exit(exitCode)
}
const (
tabWidth = 8
parserMode = parser.ParseComments
printerMode = printer.TabIndent | printer.UseSpaces
)
var printConfig = &printer.Config{
Mode: printerMode,
Tabwidth: tabWidth,
}
const parserMode = parser.ParseComments
func gofmtFile(f *ast.File) ([]byte, error) {
var buf bytes.Buffer
ast.SortImports(fset, f)
err := printConfig.Fprint(&buf, fset, f)
if err != nil {
if err := format.Node(&buf, fset, f); err != nil {
return nil, err
}
return buf.Bytes(), nil
@ -211,8 +199,7 @@ var gofmtBuf bytes.Buffer
func gofmt(n interface{}) string {
gofmtBuf.Reset()
err := printConfig.Fprint(&gofmtBuf, fset, n)
if err != nil {
if err := format.Node(&gofmtBuf, fset, n); err != nil {
return "<" + err.Error() + ">"
}
return gofmtBuf.String()

View File

@ -12,6 +12,7 @@ import (
"go/ast"
"go/build"
"go/doc"
"go/format"
"go/printer"
"go/token"
"io"
@ -356,10 +357,8 @@ func example_htmlFunc(funcName string, examples []*doc.Example, fset *token.File
// (use tabs, no comment highlight, etc).
play := ""
if eg.Play != nil && *showPlayground {
ast.SortImports(fset, eg.Play)
var buf bytes.Buffer
err := (&printer.Config{Mode: printer.TabIndent, Tabwidth: 8}).Fprint(&buf, fset, eg.Play)
if err != nil {
if err := format.Node(&buf, fset, eg.Play); err != nil {
log.Print(err)
} else {
play = buf.String()

View File

@ -7,13 +7,9 @@
package main
import (
"bytes"
"encoding/json"
"fmt"
"go/ast"
"go/parser"
"go/printer"
"go/token"
"go/format"
"net/http"
)
@ -40,36 +36,15 @@ type fmtResponse struct {
// standard gofmt formatting, and writes a fmtResponse as a JSON object.
func fmtHandler(w http.ResponseWriter, r *http.Request) {
resp := new(fmtResponse)
body, err := gofmt(r.FormValue("body"))
body, err := format.Source([]byte(r.FormValue("body")))
if err != nil {
resp.Error = err.Error()
} else {
resp.Body = body
resp.Body = string(body)
}
json.NewEncoder(w).Encode(resp)
}
// gofmt takes a Go program, formats it using the standard Go formatting
// rules, and returns it or an error.
func gofmt(body string) (string, error) {
fset := token.NewFileSet()
f, err := parser.ParseFile(fset, "prog.go", body, parser.ParseComments)
if err != nil {
return "", err
}
ast.SortImports(fset, f)
var buf bytes.Buffer
config := printer.Config{
Mode: printer.UseSpaces | printer.TabIndent,
Tabwidth: 8,
}
err = config.Fprint(&buf, fset, f)
if err != nil {
return "", err
}
return buf.String(), nil
}
// disabledHandler serves a 501 "Not Implemented" response.
func disabledHandler(w http.ResponseWriter, r *http.Request) {
w.WriteHeader(http.StatusNotImplemented)

View File

@ -57,8 +57,8 @@ func contents(name string) string {
return string(file)
}
// format returns a textual representation of the arg, formatted according to its nature.
func format(arg interface{}) string {
// stringFor returns a textual representation of the arg, formatted according to its nature.
func stringFor(arg interface{}) string {
switch arg := arg.(type) {
case int:
return fmt.Sprintf("%d", arg)
@ -87,10 +87,10 @@ func code(file string, arg ...interface{}) (s string, err error) {
// text is already whole file.
command = fmt.Sprintf("code %q", file)
case 1:
command = fmt.Sprintf("code %q %s", file, format(arg[0]))
command = fmt.Sprintf("code %q %s", file, stringFor(arg[0]))
text = oneLine(file, text, arg[0])
case 2:
command = fmt.Sprintf("code %q %s %s", file, format(arg[0]), format(arg[1]))
command = fmt.Sprintf("code %q %s %s", file, stringFor(arg[0]), stringFor(arg[1]))
text = multipleLines(file, text, arg[0], arg[1])
default:
return "", fmt.Errorf("incorrect code invocation: code %q %q", file, arg)

200
src/pkg/go/format/format.go Normal file
View File

@ -0,0 +1,200 @@
// Copyright 2012 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 format implements standard formatting of Go source.
package format
import (
"bytes"
"fmt"
"go/ast"
"go/parser"
"go/printer"
"go/token"
"io"
"strings"
)
var config = printer.Config{Mode: printer.UseSpaces | printer.TabIndent, Tabwidth: 8}
// Node formats node in canonical gofmt style and writes the result to dst.
//
// The node type must be *ast.File, *printer.CommentedNode, []ast.Decl,
// []ast.Stmt, or assignment-compatible to ast.Expr, ast.Decl, ast.Spec,
// or ast.Stmt. Node does not modify node. Imports are not sorted for
// nodes representing partial source files (i.e., if the node is not an
// *ast.File or a *printer.CommentedNode not wrapping an *ast.File).
//
// The function may return early (before the entire result is written)
// and return a formatting error, for instance due to an incorrect AST.
//
func Node(dst io.Writer, fset *token.FileSet, node interface{}) error {
// Determine if we have a complete source file (file != nil).
var file *ast.File
var cnode *printer.CommentedNode
switch n := node.(type) {
case *ast.File:
file = n
case *printer.CommentedNode:
if f, ok := n.Node.(*ast.File); ok {
file = f
cnode = n
}
}
// Sort imports if necessary.
if file != nil && hasUnsortedImports(file) {
// Make a copy of the AST because ast.SortImports is destructive.
// TODO(gri) Do this more efficently.
var buf bytes.Buffer
err := config.Fprint(&buf, fset, file)
if err != nil {
return err
}
file, err = parser.ParseFile(fset, "", buf.Bytes(), parser.ParseComments)
if err != nil {
// We should never get here. If we do, provide good diagnostic.
return fmt.Errorf("format.Node internal error (%s)", err)
}
ast.SortImports(fset, file)
// Use new file with sorted imports.
node = file
if cnode != nil {
node = &printer.CommentedNode{Node: file, Comments: cnode.Comments}
}
}
return config.Fprint(dst, fset, node)
}
// Source formats src in canonical gofmt style and writes the result to dst
// or returns an I/O or syntax error. src is expected to be a syntactically
// correct Go source file, or a list of Go declarations or statements.
//
// If src is a partial source file, the leading and trailing space of src
// is applied to the result (such that it has the same leading and trailing
// space as src), and the formatted src is indented by the same amount as
// the first line of src containing code. Imports are not sorted for partial
// source files.
//
func Source(src []byte) ([]byte, error) {
fset := token.NewFileSet()
node, err := parse(fset, src)
if err != nil {
return nil, err
}
var buf bytes.Buffer
if file, ok := node.(*ast.File); ok {
// Complete source file.
ast.SortImports(fset, file)
err := config.Fprint(&buf, fset, file)
if err != nil {
return nil, err
}
} else {
// Partial source file.
// Determine and prepend leading space.
i, j := 0, 0
for j < len(src) && isSpace(src[j]) {
if src[j] == '\n' {
i = j + 1 // index of last line in leading space
}
j++
}
buf.Write(src[:i])
// Determine indentation of first code line.
// Spaces are ignored unless there are no tabs,
// in which case spaces count as one tab.
indent := 0
hasSpace := false
for _, b := range src[i:j] {
switch b {
case ' ':
hasSpace = true
case '\t':
indent++
}
}
if indent == 0 && hasSpace {
indent = 1
}
// Format the source.
cfg := config
cfg.Indent = indent
err := cfg.Fprint(&buf, fset, node)
if err != nil {
return nil, err
}
// Determine and append trailing space.
i = len(src)
for i > 0 && isSpace(src[i-1]) {
i--
}
buf.Write(src[i:])
}
return buf.Bytes(), nil
}
func hasUnsortedImports(file *ast.File) bool {
for _, d := range file.Decls {
d, ok := d.(*ast.GenDecl)
if !ok || d.Tok != token.IMPORT {
// Not an import declaration, so we're done.
// Imports are always first.
return false
}
if d.Lparen.IsValid() {
// For now assume all grouped imports are unsorted.
// TODO(gri) Should check if they are sorted already.
return true
}
// Ungrouped imports are sorted by default.
}
return false
}
func isSpace(b byte) bool {
return b == ' ' || b == '\t' || b == '\n' || b == '\r'
}
func parse(fset *token.FileSet, src []byte) (interface{}, error) {
// Try as a complete source file.
file, err := parser.ParseFile(fset, "", src, parser.ParseComments)
if err == nil {
return file, nil
}
// If the source is missing a package clause, try as a source fragment; otherwise fail.
if !strings.Contains(err.Error(), "expected 'package'") {
return nil, err
}
// Try as a declaration list by prepending a package clause in front of src.
// Use ';' not '\n' to keep line numbers intact.
psrc := append([]byte("package p;"), src...)
file, err = parser.ParseFile(fset, "", psrc, parser.ParseComments)
if err == nil {
return file.Decls, nil
}
// If the source is missing a declaration, try as a statement list; otherwise fail.
if !strings.Contains(err.Error(), "expected declaration") {
return nil, err
}
// Try as statement list by wrapping a function around src.
fsrc := append(append([]byte("package p; func _() {"), src...), '}')
file, err = parser.ParseFile(fset, "", fsrc, parser.ParseComments)
if err == nil {
return file.Decls[0].(*ast.FuncDecl).Body.List, nil
}
// Failed, and out of options.
return nil, err
}

View File

@ -0,0 +1,125 @@
// Copyright 2012 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 format
import (
"bytes"
"go/parser"
"go/token"
"io/ioutil"
"strings"
"testing"
)
const testfile = "format_test.go"
func diff(t *testing.T, dst, src []byte) {
line := 1
offs := 0 // line offset
for i := 0; i < len(dst) && i < len(src); i++ {
d := dst[i]
s := src[i]
if d != s {
t.Errorf("dst:%d: %s\n", line, dst[offs:i+1])
t.Errorf("src:%d: %s\n", line, src[offs:i+1])
return
}
if s == '\n' {
line++
offs = i + 1
}
}
if len(dst) != len(src) {
t.Errorf("len(dst) = %d, len(src) = %d\nsrc = %q", len(dst), len(src), src)
}
}
func TestNode(t *testing.T) {
src, err := ioutil.ReadFile(testfile)
if err != nil {
t.Fatal(err)
}
fset := token.NewFileSet()
file, err := parser.ParseFile(fset, testfile, src, parser.ParseComments)
if err != nil {
t.Fatal(err)
}
var buf bytes.Buffer
if err = Node(&buf, fset, file); err != nil {
t.Fatal("Node failed:", err)
}
diff(t, buf.Bytes(), src)
}
func TestSource(t *testing.T) {
src, err := ioutil.ReadFile(testfile)
if err != nil {
t.Fatal(err)
}
res, err := Source(src)
if err != nil {
t.Fatal("Source failed:", err)
}
diff(t, res, src)
}
// Test cases that are expected to fail are marked by the prefix "ERROR".
var tests = []string{
// declaration lists
`import "go/format"`,
"var x int",
"var x int\n\ntype T struct{}",
// statement lists
"x := 0",
"f(a, b, c)\nvar x int = f(1, 2, 3)",
// indentation, leading and trailing space
"\tx := 0\n\tgo f()",
"\tx := 0\n\tgo f()\n\n\n",
"\n\t\t\n\n\tx := 0\n\tgo f()\n\n\n",
"\n\t\t\n\n\t\t\tx := 0\n\t\t\tgo f()\n\n\n",
"\n\t\t\n\n\t\t\tx := 0\n\t\t\tconst s = `\nfoo\n`\n\n\n", // no indentation inside raw strings
// erroneous programs
"ERRORvar x",
"ERROR1 + 2 +",
"ERRORx := 0",
}
func String(s string) (string, error) {
res, err := Source([]byte(s))
if err != nil {
return "", err
}
return string(res), nil
}
func TestPartial(t *testing.T) {
for _, src := range tests {
if strings.HasPrefix(src, "ERROR") {
// test expected to fail
src = src[5:] // remove ERROR prefix
res, err := String(src)
if err == nil && res == src {
t.Errorf("formatting succeeded but was expected to fail:\n%q", src)
}
} else {
// test expected to succeed
res, err := String(src)
if err != nil {
t.Errorf("formatting failed (%s):\n%q", err, src)
} else if res != src {
t.Errorf("formatting incorrect:\nsource: %q\nresult: %q", src, res)
}
}
}
}