go/src/cmd/gofmt/internal.go

// parse parses src, which was read from the named file,
// as a Go source file, declaration, or statement list.
func parse(fset *token.FileSet, filename string, src []byte, fragmentOk bool) (
	file *ast.File,
	sourceAdj func(src []byte, indent int) []byte,
	indentAdj int,
	err error,
) { … }

// format formats the given package file originally obtained from src
// and adjusts the result based on the original source via sourceAdj
// and indentAdj.
func format(
	fset *token.FileSet,
	file *ast.File,
	sourceAdj func(src []byte, indent int) []byte,
	indentAdj int,
	src []byte,
	cfg printer.Config,
) ([]byte, error) { … }

// isSpace reports whether the byte is a space character.
// isSpace defines a space as being among the following bytes: ' ', '\t', '\n' and '\r'.
func isSpace(b byte) bool { … }