// 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)
}
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")
}
// This tests that uses of existing vars on the LHS of an assignment
// are Uses, not Defs; and also that the (illegal) use of a non-var on
// the LHS of an assignment is a Use nonetheless.
func TestIssue7827(t *testing.T) {
const src = `
package p
func _() {
const w = 1 // defs w
x, y := 2, 3 // defs x, y
w, x, z := 4, 5, 6 // uses w, x, defs z; error: cannot assign to w
_, _, _ = x, y, z // uses x, y, z
}
`
const want = `L3 defs func p._()
L4 defs const w untyped int
L5 defs var x int
L5 defs var y int
L6 defs var z int
L6 uses const w untyped int
L6 uses var x int
L7 uses var x int
L7 uses var y int
L7 uses var z int`
f, err := parser.ParseFile(fset, "", src, 0)
if err != nil {
t.Fatal(err)
}
// don't abort at the first error
conf := Config{Error: func(err error) { t.Log(err) }}
defs := make(map[*ast.Ident]Object)
uses := make(map[*ast.Ident]Object)
_, err = conf.Check(f.Name.Name, fset, []*ast.File{f}, &Info{Defs: defs, Uses: uses})
if s := fmt.Sprint(err); !strings.HasSuffix(s, "cannot assign to w") {
t.Errorf("Check: unexpected error: %s", s)
}
var facts []string
for id, obj := range defs {
if obj != nil {
fact := fmt.Sprintf("L%d defs %s", fset.Position(id.Pos()).Line, obj)
facts = append(facts, fact)
}
}
for id, obj := range uses {
fact := fmt.Sprintf("L%d uses %s", fset.Position(id.Pos()).Line, obj)
facts = append(facts, fact)
}
sort.Strings(facts)
got := strings.Join(facts, "\n")
if got != want {
t.Errorf("Unexpected defs/uses\ngot:\n%s\nwant:\n%s", got, want)
}
}
// 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 TestIssue5770(t *testing.T) {
src := `package p; type S struct{T}`
f, err := parser.ParseFile(fset, "", src, 0)
if err != nil {
t.Fatal(err)
}
conf := Config{Importer: importer.Default([]*ast.File{f})}
_, err = conf.Check(f.Name.Name, fset, []*ast.File{f}, nil) // do not crash
want := "undeclared name: T"
if err == nil || !strings.Contains(err.Error(), want) {
t.Errorf("got: %v; want: %s", err, want)
}
}
// findInterval parses input and returns the [start, end) positions of
// the first occurrence of substr in input. f==nil indicates failure;
// an error has already been reported in that case.
//
func findInterval(t *testing.T, fset *token.FileSet, input, substr string) (f *ast.File, start, end token.Pos) {
f, err := parser.ParseFile(fset, "<input>", input, 0)
if err != nil {
t.Errorf("parse error: %s", err)
return
}
i := strings.Index(input, substr)
if i < 0 {
t.Errorf("%q is not a substring of input", substr)
f = nil
return
}
filePos := fset.File(f.Package)
return f, filePos.Pos(i), filePos.Pos(i + len(substr))
}
func TestIssue5849(t *testing.T) {
src := `
package p
var (
s uint
_ = uint8(8)
_ = uint16(16) << s
_ = uint32(32 << s)
_ = uint64(64 << s + s)
_ = (interface{})("foo")
)`
f, err := parser.ParseFile(fset, "", src, 0)
if err != nil {
t.Fatal(err)
}
var conf Config
types := make(map[ast.Expr]TypeAndValue)
_, err = conf.Check(f.Name.Name, fset, []*ast.File{f}, &Info{Types: types})
if err != nil {
t.Fatal(err)
}
for x, tv := range types {
var want Type
switch x := x.(type) {
case *ast.BasicLit:
switch x.Value {
case `8`:
want = Typ[Uint8]
case `16`:
want = Typ[Uint16]
case `32`:
want = Typ[Uint32]
case `64`:
want = Typ[Uint] // because of "+ s", s is of type uint
case `"foo"`:
want = Typ[String]
}
}
if want != nil && !Identical(tv.Type, want) {
t.Errorf("got %s; want %s", tv.Type, want)
}
}
}
// 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++
}
}
// ExampleMethodSet prints the method sets of various types.
func ExampleMethodSet() {
// Parse a single source file.
const input = `
package temperature
import "fmt"
type Celsius float64
func (c Celsius) String() string { return fmt.Sprintf("%g°C", c) }
func (c *Celsius) SetF(f float64) { *c = Celsius(f - 32 / 9 * 5) }
`
fset := token.NewFileSet()
f, err := parser.ParseFile(fset, "celsius.go", input, 0)
if err != nil {
log.Fatal(err)
}
// Type-check a package consisting of this file.
// Type information for the imported packages
// comes from $GOROOT/pkg/$GOOS_$GOOARCH/fmt.a.
conf := types.Config{Importer: importer.Default([]*ast.File{f})}
pkg, err := conf.Check("temperature", fset, []*ast.File{f}, nil)
if err != nil {
log.Fatal(err)
}
// Print the method sets of Celsius and *Celsius.
celsius := pkg.Scope().Lookup("Celsius").Type()
for _, t := range []types.Type{celsius, types.NewPointer(celsius)} {
fmt.Printf("Method set of %s:\n", t)
mset := types.NewMethodSet(t)
for i := 0; i < mset.Len(); i++ {
fmt.Println(mset.At(i))
}
fmt.Println()
}
// Output:
// Method set of temperature.Celsius:
// method (temperature.Celsius) String() string
//
// Method set of *temperature.Celsius:
// method (*temperature.Celsius) SetF(f float64)
// method (*temperature.Celsius) String() string
}
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)
}
}
}
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 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 TestImports(t *testing.T) {
fset := token.NewFileSet()
for _, test := range importsTests {
f, err := parser.ParseFile(fset, "test.go", test.in, 0)
if err != nil {
t.Errorf("%s: %v", test.name, err)
continue
}
var got [][]string
for _, group := range Imports(fset, f) {
var b []string
for _, spec := range group {
b = append(b, unquote(spec.Path.Value))
}
got = append(got, b)
}
if !reflect.DeepEqual(got, test.want) {
t.Errorf("Imports(%s)=%v, want %v", test.name, got, test.want)
}
}
}
func parseFiles(t *testing.T, filenames []string) ([]*ast.File, []error) {
var files []*ast.File
var errlist []error
for _, filename := range filenames {
file, err := parser.ParseFile(fset, filename, nil, parser.AllErrors)
if file == nil {
t.Fatalf("%s: %s", filename, err)
}
files = append(files, file)
if err != nil {
if list, _ := err.(scanner.ErrorList); len(list) > 0 {
for _, err := range list {
errlist = append(errlist, err)
}
} else {
errlist = append(errlist, err)
}
}
}
return files, errlist
}
// 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
}
// This example demonstrates how to inspect the AST of a Go program.
func ExampleInspect() {
// src is the input for which we want to inspect the AST.
src := `
package p
const c = 1.0
var X = f(3.14)*2 + c
`
// Create the AST by parsing src.
fset := token.NewFileSet() // positions are relative to fset
f, err := parser.ParseFile(fset, "src.go", src, 0)
if err != nil {
panic(err)
}
// Inspect the AST and print all identifiers and literals.
ast.Inspect(f, func(n ast.Node) bool {
var s string
switch x := n.(type) {
case *ast.BasicLit:
s = x.Value
case *ast.Ident:
s = x.Name
}
if s != "" {
fmt.Printf("%s:\t%s\n", fset.Position(n.Pos()), s)
}
return true
})
// output:
// src.go:2:9: p
// src.go:3:7: c
// src.go:3:11: 1.0
// src.go:4:5: X
// src.go:4:9: f
// src.go:4:11: 3.14
// src.go:4:17: 2
// src.go:4:21: c
}