Golang parser.ParseFile函数代码示例

// format parses src, prints the corresponding AST, verifies the resulting
// src is syntactically correct, and returns the resulting src or an error
// if any.
func format(src []byte, mode checkMode) ([]byte, error) {
	// parse src
	f, err := parser.ParseFile(fset, "", src, parser.ParseComments)
	if err != nil {
		return nil, fmt.Errorf("parse: %s\n%s", err, src)
	}

	// filter exports if necessary
	if mode&export != 0 {
		ast.FileExports(f) // ignore result
		f.Comments = nil   // don't print comments that are not in AST
	}

	// determine printer configuration
	cfg := Config{Tabwidth: tabwidth}
	if mode&rawFormat != 0 {
		cfg.Mode |= RawFormat
	}

	// print AST
	var buf bytes.Buffer
	if err := cfg.Fprint(&buf, fset, f); err != nil {
		return nil, fmt.Errorf("print: %s", err)
	}

	// make sure formatted output is syntactically correct
	res := buf.Bytes()
	if _, err := parser.ParseFile(fset, "", res, 0); err != nil {
		return nil, fmt.Errorf("re-parse: %s\n%s", err, buf.Bytes())
	}

	return res, nil
}

// Verify that the printer produces a correct program
// even if the position information of comments introducing newlines
// is incorrect.
func TestBadComments(t *testing.T) {
	const src = `
// first comment - text and position changed by test
package p
import "fmt"
const pi = 3.14 // rough circle
var (
	x, y, z int = 1, 2, 3
	u, v float64
)
func fibo(n int) {
	if n < 2 {
		return n /* seed values */
	}
	return fibo(n-1) + fibo(n-2)
}
`

	f, err := parser.ParseFile(fset, "", src, parser.ParseComments)
	if err != nil {
		t.Error(err) // error in test
	}

	comment := f.Comments[0].List[0]
	pos := comment.Pos()
	if fset.Position(pos).Offset != 1 {
		t.Error("expected offset 1") // error in test
	}

	testComment(t, f, len(src), &ast.Comment{Slash: pos, Text: "//-style comment"})
	testComment(t, f, len(src), &ast.Comment{Slash: pos, Text: "/*-style comment */"})
	testComment(t, f, len(src), &ast.Comment{Slash: pos, Text: "/*-style \n comment */"})
	testComment(t, f, len(src), &ast.Comment{Slash: pos, Text: "/*-style comment \n\n\n */"})
}

// addFile adds a file to the set. The pkg must be of the form
// "canonical/pkg/path" and the path must be the absolute path to the file. A
// flag indicates whether this file was user-requested or just from following
// the import graph.
func (b *Builder) addFile(pkg string, path string, src []byte, userRequested bool) error {
	p, err := parser.ParseFile(b.fset, path, src, parser.DeclarationErrors|parser.ParseComments)
	if err != nil {
		return err
	}
	dirPath := filepath.Dir(path)
	if prev, found := b.absPaths[pkg]; found {
		if dirPath != prev {
			return fmt.Errorf("package %q (%s) previously resolved to %s", pkg, dirPath, prev)
		}
	} else {
		b.absPaths[pkg] = dirPath
	}
	b.parsed[pkg] = append(b.parsed[pkg], parsedFile{path, p})
	b.userRequested[pkg] = userRequested
	for _, c := range p.Comments {
		position := b.fset.Position(c.End())
		b.endLineToCommentGroup[fileLine{position.Filename, position.Line}] = c
	}

	// We have to get the packages from this specific file, in case the
	// user added individual files instead of entire directories.
	if b.importGraph[pkg] == nil {
		b.importGraph[pkg] = map[string]struct{}{}
	}
	for _, im := range p.Imports {
		importedPath := strings.Trim(im.Path.Value, `"`)
		b.importGraph[pkg][importedPath] = struct{}{}
	}
	return nil
}

// TestLineComments, using a simple test case, checks that consecutive line
// comments are properly terminated with a newline even if the AST position
// information is incorrect.
//
func TestLineComments(t *testing.T) {
	const src = `// comment 1
	// comment 2
	// comment 3
	package main
	`

	fset := token.NewFileSet()
	f, err := parser.ParseFile(fset, "", src, parser.ParseComments)
	if err != nil {
		panic(err) // error in test
	}

	var buf bytes.Buffer
	fset = token.NewFileSet() // use the wrong file set
	Fprint(&buf, fset, f)

	nlines := 0
	for _, ch := range buf.Bytes() {
		if ch == '\n' {
			nlines++
		}
	}

	const expected = 3
	if nlines < expected {
		t.Errorf("got %d, expected %d\n", nlines, expected)
		t.Errorf("result:\n%s", buf.Bytes())
	}
}

func parseFunc(filename, functionname string) (fun *ast.FuncDecl, fset *token.FileSet) {
	fset = token.NewFileSet()
	if file, err := parser.ParseFile(fset, filename, nil, 0); err == nil {
		for _, d := range file.Decls {
			if f, ok := d.(*ast.FuncDecl); ok && f.Name.Name == functionname {
				fun = f
				return
			}
		}
	}
	panic("function not found")
}

// Verify that the printer doesn't crash if the AST contains BadXXX nodes.
func TestBadNodes(t *testing.T) {
	const src = "package p\n("
	const res = "package p\nBadDecl\n"
	f, err := parser.ParseFile(fset, "", src, parser.ParseComments)
	if err == nil {
		t.Error("expected illegal program") // error in test
	}
	var buf bytes.Buffer
	Fprint(&buf, fset, f)
	if buf.String() != res {
		t.Errorf("got %q, expected %q", buf.String(), res)
	}
}

func RewriteTypesWithProtobufStructTags(name string, structTags map[string]map[string]string) error {
	fset := token.NewFileSet()
	src, err := ioutil.ReadFile(name)
	if err != nil {
		return err
	}
	file, err := parser.ParseFile(fset, name, src, parser.DeclarationErrors|parser.ParseComments)
	if err != nil {
		return err
	}

	allErrs := []error{}

	// set any new struct tags
	for _, d := range file.Decls {
		if errs := updateStructTags(d, structTags, []string{"protobuf"}); len(errs) > 0 {
			allErrs = append(allErrs, errs...)
		}
	}

	if len(allErrs) > 0 {
		var s string
		for _, err := range allErrs {
			s += err.Error() + "\n"
		}
		return errors.New(s)
	}

	b := &bytes.Buffer{}
	if err := printer.Fprint(b, fset, file); err != nil {
		return err
	}

	body, err := format.Source(b.Bytes())
	if err != nil {
		return fmt.Errorf("%s\n---\nunable to format %q: %v", b, name, err)
	}

	f, err := os.OpenFile(name, os.O_WRONLY|os.O_TRUNC, 0644)
	if err != nil {
		return err
	}
	defer f.Close()
	if _, err := f.Write(body); err != nil {
		return err
	}
	return f.Close()
}

func RewriteGeneratedGogoProtobufFile(name string, packageName string, typeExistsFn func(string) bool, header []byte) error {
	fset := token.NewFileSet()
	src, err := ioutil.ReadFile(name)
	if err != nil {
		return err
	}
	file, err := parser.ParseFile(fset, name, src, parser.DeclarationErrors|parser.ParseComments)
	if err != nil {
		return err
	}
	cmap := ast.NewCommentMap(fset, file, file.Comments)

	// remove types that are already declared
	decls := []ast.Decl{}
	for _, d := range file.Decls {
		if !dropExistingTypeDeclarations(d, typeExistsFn) {
			decls = append(decls, d)
		}
	}
	file.Decls = decls

	// remove unmapped comments
	file.Comments = cmap.Filter(file).Comments()

	b := &bytes.Buffer{}
	b.Write(header)
	if err := printer.Fprint(b, fset, file); err != nil {
		return err
	}

	body, err := format.Source(b.Bytes())
	if err != nil {
		return err
	}

	f, err := os.OpenFile(name, os.O_WRONLY|os.O_TRUNC, 0644)
	if err != nil {
		return err
	}
	defer f.Close()
	if _, err := f.Write(body); err != nil {
		return err
	}
	return f.Close()
}

// testComment verifies that f can be parsed again after printing it
// with its first comment set to comment at any possible source offset.
func testComment(t *testing.T, f *ast.File, srclen int, comment *ast.Comment) {
	f.Comments[0].List[0] = comment
	var buf bytes.Buffer
	for offs := 0; offs <= srclen; offs++ {
		buf.Reset()
		// Printing f should result in a correct program no
		// matter what the (incorrect) comment position is.
		if err := Fprint(&buf, fset, f); err != nil {
			t.Error(err)
		}
		if _, err := parser.ParseFile(fset, "", buf.Bytes(), 0); err != nil {
			t.Fatalf("incorrect program for pos = %d:\n%s", comment.Slash, buf.String())
		}
		// Position information is just an offset.
		// Move comment one byte down in the source.
		comment.Slash++
	}
}

func TestStmtLists(t *testing.T) {
	for _, src := range stmts {
		file, err := parser.ParseFile(fset, "", "package p; func _() {"+src+"}", parser.ParseComments)
		if err != nil {
			panic(err) // error in test
		}

		var buf bytes.Buffer
		err = Fprint(&buf, fset, file.Decls[0].(*ast.FuncDecl).Body.List) // only print statements
		if err != nil {
			panic(err) // error in test
		}

		out := buf.String()
		if out != src {
			t.Errorf("\ngot : %q\nwant: %q\n", out, src)
		}
	}
}

func TestDeclLists(t *testing.T) {
	for _, src := range decls {
		file, err := parser.ParseFile(fset, "", "package p;"+src, parser.ParseComments)
		if err != nil {
			panic(err) // error in test
		}

		var buf bytes.Buffer
		err = Fprint(&buf, fset, file.Decls) // only print declarations
		if err != nil {
			panic(err) // error in test
		}

		out := buf.String()
		if out != src {
			t.Errorf("\ngot : %q\nwant: %q\n", out, src)
		}
	}
}

// cannot initialize in init because (printer) Fprint launches goroutines.
func initialize() {
	const filename = "testdata/parser.go"

	src, err := ioutil.ReadFile(filename)
	if err != nil {
		log.Fatalf("%s", err)
	}

	file, err := parser.ParseFile(fset, filename, src, parser.ParseComments)
	if err != nil {
		log.Fatalf("%s", err)
	}

	var buf bytes.Buffer
	testprint(&buf, file)
	if !bytes.Equal(buf.Bytes(), src) {
		log.Fatalf("print error: %s not idempotent", filename)
	}

	testfile = file
}

func TestBaseIndent(t *testing.T) {
	// The testfile must not contain multi-line raw strings since those
	// are not indented (because their values must not change) and make
	// this test fail.
	const filename = "printer.go"
	src, err := ioutil.ReadFile(filename)
	if err != nil {
		panic(err) // error in test
	}

	file, err := parser.ParseFile(fset, filename, src, 0)
	if err != nil {
		panic(err) // error in test
	}

	var buf bytes.Buffer
	for indent := 0; indent < 4; indent++ {
		buf.Reset()
		(&Config{Tabwidth: tabwidth, Indent: indent}).Fprint(&buf, fset, file)
		// all code must be indented by at least 'indent' tabs
		lines := bytes.Split(buf.Bytes(), []byte{'\n'})
		for i, line := range lines {
			if len(line) == 0 {
				continue // empty lines don't have indentation
			}
			n := 0
			for j, b := range line {
				if b != '\t' {
					// end of indentation
					n = j
					break
				}
			}
			if n < indent {
				t.Errorf("line %d: got only %d tabs; want at least %d: %q", i, n, indent, line)
			}
		}
	}
}

func ExampleParseFile() {
	fset := token.NewFileSet() // positions are relative to fset

	// Parse the file containing this very example
	// but stop after processing the imports.
	f, err := parser.ParseFile(fset, "example_test.go", nil, parser.ImportsOnly)
	if err != nil {
		fmt.Println(err)
		return
	}

	// Print the imports from the file's AST.
	for _, s := range f.Imports {
		fmt.Println(s.Path.Value)
	}

	// output:
	//
	// "fmt"
	// "k8s.io/kubernetes/third_party/golang/go/parser"
	// "k8s.io/kubernetes/third_party/golang/go/token"
}

func TestCommentMap(t *testing.T) {
	fset := token.NewFileSet()
	f, err := parser.ParseFile(fset, "", src, parser.ParseComments)
	if err != nil {
		t.Fatal(err)
	}
	cmap := NewCommentMap(fset, f, f.Comments)

	// very correct association of comments
	for n, list := range cmap {
		key := fmt.Sprintf("%2d: %T", fset.Position(n.Pos()).Line, n)
		got := ctext(list)
		want := res[key]
		if got != want {
			t.Errorf("%s: got %q; want %q", key, got, want)
		}
	}

	// verify that no comments got lost
	if n := len(cmap.Comments()); n != len(f.Comments) {
		t.Errorf("got %d comment groups in map; want %d", n, len(f.Comments))
	}

	// support code to update test:
	// set genMap to true to generate res map
	const genMap = false
	if genMap {
		out := make([]string, 0, len(cmap))
		for n, list := range cmap {
			out = append(out, fmt.Sprintf("\t\"%2d: %T\":\t%q,", fset.Position(n.Pos()).Line, n, ctext(list)))
		}
		sort.Strings(out)
		for _, s := range out {
			fmt.Println(s)
		}
	}
}