func ExampleFprint() {
// Parse source file and extract the AST without comments for
// this function, with position information referring to the
// file set fset.
funcAST, fset := parseFunc("example_test.go", "ExampleFprint")
// Print the function body into buffer buf.
// The file set is provided to the printer so that it knows
// about the original source formatting and can add additional
// line breaks where they were present in the source.
var buf bytes.Buffer
printer.Fprint(&buf, fset, funcAST.Body)
// Remove braces {} enclosing the function body, unindent,
// and trim leading and trailing white space.
s := buf.String()
s = s[1 : len(s)-1]
s = strings.TrimSpace(strings.Replace(s, "\n\t", "\n", -1))
// Print the cleaned-up body text to stdout.
fmt.Println(s)
// output:
// funcAST, fset := parseFunc("example_test.go", "ExampleFprint")
//
// var buf bytes.Buffer
// printer.Fprint(&buf, fset, funcAST.Body)
//
// s := buf.String()
// s = s[1 : len(s)-1]
// s = strings.TrimSpace(strings.Replace(s, "\n\t", "\n", -1))
//
// fmt.Println(s)
}
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()
}
func rewriteFile(name string, header []byte, rewriteFn func(*token.FileSet, *ast.File) error) 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
}
if err := rewriteFn(fset, file); err != nil {
return err
}
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()
}
func nodeFmt(node interface{}, fset *token.FileSet) string {
var buf bytes.Buffer
printer.Fprint(&buf, fset, node)
return strings.Replace(strings.TrimSpace(buf.String()), "\n", "\n\t", -1)
}