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
}

func TestIssue8518(t *testing.T) {
	fset := token.NewFileSet()
	imports := make(testImporter)
	conf := Config{
		Error:    func(err error) { t.Log(err) }, // don't exit after first error
		Importer: imports,
	}
	makePkg := func(path, src string) {
		f, err := parser.ParseFile(fset, path, src, 0)
		if err != nil {
			t.Fatal(err)
		}
		pkg, _ := conf.Check(path, fset, []*ast.File{f}, nil) // errors logged via conf.Error
		imports[path] = pkg
	}

	const libSrc = `
package a
import "missing"
const C1 = foo
const C2 = missing.C
`

	const mainSrc = `
package main
import "a"
var _ = a.C1
var _ = a.C2
`

	makePkg("a", libSrc)
	makePkg("main", mainSrc) // don't crash when type-checking this package
}

func TestMultiFileInitOrder(t *testing.T) {
	fset := token.NewFileSet()
	mustParse := func(src string) *ast.File {
		f, err := parser.ParseFile(fset, "main", src, 0)
		if err != nil {
			t.Fatal(err)
		}
		return f
	}

	fileA := mustParse(`package main; var a = 1`)
	fileB := mustParse(`package main; var b = 2`)

	// The initialization order must not depend on the parse
	// order of the files, only on the presentation order to
	// the type-checker.
	for _, test := range []struct {
		files []*ast.File
		want  string
	}{
		{[]*ast.File{fileA, fileB}, "[a = 1 b = 2]"},
		{[]*ast.File{fileB, fileA}, "[b = 2 a = 1]"},
	} {
		var info Info
		if _, err := new(Config).Check("main", fset, test.files, &info); err != nil {
			t.Fatal(err)
		}
		if got := fmt.Sprint(info.InitOrder); got != test.want {
			t.Fatalf("got %s; want %s", got, test.want)
		}
	}
}

func TestExamples(t *testing.T) {
	fset := token.NewFileSet()
	file, err := parser.ParseFile(fset, "test.go", strings.NewReader(exampleTestFile), parser.ParseComments)
	if err != nil {
		t.Fatal(err)
	}
	for i, e := range doc.Examples(file) {
		c := exampleTestCases[i]
		if e.Name != c.Name {
			t.Errorf("got Name == %q, want %q", e.Name, c.Name)
		}
		if w := c.Play; w != "" {
			var g string // hah
			if e.Play == nil {
				g = "<nil>"
			} else {
				var buf bytes.Buffer
				if err := format.Node(&buf, fset, e.Play); err != nil {
					t.Fatal(err)
				}
				g = buf.String()
			}
			if g != w {
				t.Errorf("%s: got Play == %q, want %q", c.Name, g, w)
			}
		}
		if g, w := e.Output, c.Output; g != w {
			t.Errorf("%s: got Output == %q, want %q", c.Name, g, w)
		}
	}
}

func TestFilterDuplicates(t *testing.T) {
	// parse input
	fset := token.NewFileSet()
	file, err := parser.ParseFile(fset, "", input, 0)
	if err != nil {
		t.Fatal(err)
	}

	// create package
	files := map[string]*ast.File{"": file}
	pkg, err := ast.NewPackage(fset, files, nil, nil)
	if err != nil {
		t.Fatal(err)
	}

	// filter
	merged := ast.MergePackageFiles(pkg, ast.FilterFuncDuplicates)

	// pretty-print
	var buf bytes.Buffer
	if err := format.Node(&buf, fset, merged); err != nil {
		t.Fatal(err)
	}
	output := buf.String()

	if output != golden {
		t.Errorf("incorrect output:\n%s", output)
	}
}

func parse(t *testing.T, name, in string) *ast.File {
	file, err := parser.ParseFile(fset, name, in, parser.ParseComments)
	if err != nil {
		t.Fatalf("%s parse: %v", name, err)
	}
	return file
}

// 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 */"})
}

// 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 ExampleConvertAST() {
	fset := token.NewFileSet()
	a, _ := parser.ParseFile(fset, "example.sgo", `
	package example

	type LinkedList struct {
		Head	int
		// For SGo: ?*LinkedList
		Tail	*LinkedList
	}
	`, parser.ParseComments)

	info := &types.Info{
		Defs: map[*ast.Ident]types.Object{},
		Uses: map[*ast.Ident]types.Object{},
	}
	cfg := &types.Config{}
	cfg.Check("", fset, []*ast.File{a}, info)

	importer.ConvertAST(a, info, nil)

	printer.Fprint(os.Stdout, fset, a)
	// Output:
	// package example
	//
	// type LinkedList struct {
	// 	Head	int
	// 	// For SGo: ?*LinkedList
	// 	Tail	?*LinkedList
	// }
}

func TestIssue7245(t *testing.T) {
	src := `
package p
func (T) m() (res bool) { return }
type T struct{} // receiver type after method declaration
`
	f, err := parser.ParseFile(fset, "", src, 0)
	if err != nil {
		t.Fatal(err)
	}

	var conf Config
	defs := make(map[*ast.Ident]Object)
	_, err = conf.Check(f.Name.Name, fset, []*ast.File{f}, &Info{Defs: defs})
	if err != nil {
		t.Fatal(err)
	}

	m := f.Decls[0].(*ast.FuncDecl)
	res1 := defs[m.Name].(*Func).Type().(*Signature).Results().At(0)
	res2 := defs[m.Type.Results.List[0].Names[0]].(*Var)

	if res1 != res2 {
		t.Errorf("got %s (%p) != %s (%p)", res1, res2, res1, res2)
	}
}

func loadExportsGoPath(dir string) map[string]bool {
	exports := make(map[string]bool)
	buildPkg, err := build.ImportDir(dir, 0)
	if err != nil {
		if strings.Contains(err.Error(), "no buildable Go source files in") {
			return nil
		}
		fmt.Fprintf(os.Stderr, "could not import %q: %v\n", dir, err)
		return nil
	}
	fset := token.NewFileSet()
	for _, files := range [...][]string{buildPkg.GoFiles, buildPkg.CgoFiles} {
		for _, file := range files {
			f, err := parser.ParseFile(fset, filepath.Join(dir, file), nil, 0)
			if err != nil {
				fmt.Fprintf(os.Stderr, "could not parse %q: %v\n", file, err)
				continue
			}
			for name := range f.Scope.Objects {
				if ast.IsExported(name) {
					exports[name] = true
				}
			}
		}
	}
	return exports
}

// For SGo: func(whence string, files ...NamedFile) ([][]byte, []error)
func TranslateFilesFrom(whence string, files ...NamedFile) ([][]byte, []error) {
	var errs []error
	fset := token.NewFileSet()

	cwd, err := os.Getwd()
	if err != nil {
		return nil, []error{err}
	}

	var parsed []*ast.File
	var srcs [][]byte
	for _, named := range files {
		src, err := ioutil.ReadAll(named.File)
		if err != nil {
			errs = append(errs, err)
			continue
		}
		relPath, err := filepath.Rel(cwd, named.Path)
		if err != nil {
			relPath = named.Path
		}
		file, err := parser.ParseFile(fset, relPath, src, parser.ParseComments)
		if err != nil {
			errs = append(errs, err)
			continue
		}
		srcs = append(srcs, src)
		parsed = append(parsed, file)
	}

	// Early typecheck, because fileWithAnnotationComments adds lines and
	// then type errors are reported in the wrong line.
	_, typeErrs := typecheck("translate", fset, whence, parsed...)
	if len(typeErrs) > 0 {
		errs = append(errs, makeErrList(fset, typeErrs))
		return nil, errs
	}

	oldFset := fset
	fset = token.NewFileSet() // fileWithAnnotationComments will reparse.
	for i, p := range parsed {
		var err error
		srcs[i], parsed[i], err = fileWithAnnotationComments(p, fset, oldFset, srcs[i])
		if err != nil {
			errs = append(errs, err)
		}
	}
	if len(errs) > 0 {
		return nil, errs
	}

	info, typeErrs := typecheck("translate", fset, whence, parsed...)
	if len(typeErrs) > 0 {
		errs = append(errs, makeErrList(fset, typeErrs))
		return nil, errs
	}

	return translate(info, srcs, parsed, fset), errs
}

// This example illustrates how to remove a variable declaration
// in a Go program while maintaining correct comment association
// using an ast.CommentMap.
func ExampleCommentMap() {
	// src is the input for which we create the AST that we
	// are going to manipulate.
	src := `
// This is the package comment.
package main

// This comment is associated with the hello constant.
const hello = "Hello, World!" // line comment 1

// This comment is associated with the foo variable.
var foo = hello // line comment 2 

// This comment is associated with the main function.
func main() {
	fmt.Println(hello) // line comment 3
}
`

	// Create the AST by parsing src.
	fset := token.NewFileSet() // positions are relative to fset
	f, err := parser.ParseFile(fset, "src.go", src, parser.ParseComments)
	if err != nil {
		panic(err)
	}

	// Create an ast.CommentMap from the ast.File's comments.
	// This helps keeping the association between comments
	// and AST nodes.
	cmap := ast.NewCommentMap(fset, f, f.Comments)

	// Remove the first variable declaration from the list of declarations.
	f.Decls = removeFirstVarDecl(f.Decls)

	// Use the comment map to filter comments that don't belong anymore
	// (the comments associated with the variable declaration), and create
	// the new comments list.
	f.Comments = cmap.Filter(f).Comments()

	// Print the modified AST.
	var buf bytes.Buffer
	if err := format.Node(&buf, fset, f); err != nil {
		panic(err)
	}
	fmt.Printf("%s", buf.Bytes())

	// output:
	// // This is the package comment.
	// package main
	//
	// // This comment is associated with the hello constant.
	// const hello = "Hello, World!" // line comment 1
	//
	// // This comment is associated with the main function.
	// func main() {
	// 	fmt.Println(hello) // line comment 3
	// }
}

func pkgFor(path, source string, info *Info) (*Package, error) {
	fset := token.NewFileSet()
	f, err := parser.ParseFile(fset, path, source, 0)
	if err != nil {
		return nil, err
	}

	conf := Config{Importer: importer.Default([]*ast.File{f}), AllowUseUninitializedVars: true, AllowUninitializedExprs: true}
	return conf.Check(f.Name.Name, fset, []*ast.File{f}, info)
}

func makePkg(t *testing.T, src string) (*Package, error) {
	fset := token.NewFileSet()
	file, err := parser.ParseFile(fset, filename, src, parser.DeclarationErrors)
	if err != nil {
		return nil, err
	}
	// use the package name as package path
	conf := Config{Importer: importer.Default([]*ast.File{file})}
	return conf.Check(file.Name.Name, fset, []*ast.File{file}, nil)
}