func ExampleScanner_Scan() { // src is the input that we want to tokenize. src := []byte(`[profile "A"] color = blue ; Comment`) // Initialize the scanner. var s scanner.Scanner fset := token.NewFileSet() // positions are relative to fset file := fset.AddFile("", fset.Base(), len(src)) // register input "file" s.Init(file, src, nil /* no error handler */, scanner.ScanComments) // Repeated calls to Scan yield the token sequence found in the input. for { pos, tok, lit := s.Scan() if tok == token.EOF { break } fmt.Printf("%s\t%q\t%q\n", fset.Position(pos), tok, lit) } // output: // 1:1 "[" "" // 1:2 "IDENT" "profile" // 1:10 "STRING" "\"A\"" // 1:13 "]" "" // 1:14 "\n" "" // 2:1 "IDENT" "color" // 2:7 "=" "" // 2:9 "STRING" "blue" // 2:14 "COMMENT" "; Comment" }
func readInto(config interface{}, fset *token.FileSet, file *token.File, src []byte) error { var s scanner.Scanner var errs scanner.ErrorList s.Init(file, src, func(p token.Position, m string) { errs.Add(p, m) }, 0) sect, sectsub := "", "" pos, tok, lit := s.Scan() errfn := func(msg string) error { return fmt.Errorf("%s: %s", fset.Position(pos), msg) } for { if errs.Len() > 0 { return errs.Err() } switch tok { case token.EOF: return nil case token.EOL, token.COMMENT: pos, tok, lit = s.Scan() case token.LBRACK: pos, tok, lit = s.Scan() if errs.Len() > 0 { return errs.Err() } if tok != token.IDENT { return errfn("expected section name") } sect, sectsub = lit, "" pos, tok, lit = s.Scan() if errs.Len() > 0 { return errs.Err() } if tok == token.STRING { sectsub = unquote(lit) if sectsub == "" { return errfn("empty subsection name") } pos, tok, lit = s.Scan() if errs.Len() > 0 { return errs.Err() } } if tok != token.RBRACK { if sectsub == "" { return errfn("expected subsection name or right bracket") } return errfn("expected right bracket") } pos, tok, lit = s.Scan() if tok != token.EOL && tok != token.EOF && tok != token.COMMENT { return errfn("expected EOL, EOF, or comment") } case token.IDENT: if sect == "" { return errfn("expected section header") } n := lit pos, tok, lit = s.Scan() if errs.Len() > 0 { return errs.Err() } blank, v := tok == token.EOF || tok == token.EOL || tok == token.COMMENT, "" if !blank { if tok != token.ASSIGN { return errfn("expected '='") } pos, tok, lit = s.Scan() if errs.Len() > 0 { return errs.Err() } if tok != token.STRING { return errfn("expected value") } v = unquote(lit) pos, tok, lit = s.Scan() if errs.Len() > 0 { return errs.Err() } if tok != token.EOL && tok != token.EOF && tok != token.COMMENT { return errfn("expected EOL, EOF, or comment") } } err := set(config, sect, sectsub, n, blank, v) if err != nil { return err } default: if sect == "" { return errfn("expected section header") } return errfn("expected section header or variable declaration") } } panic("never reached") }