text/scanner包函数列表 Constants func TokenString(tok rune) string type Position func (pos *Position) IsValid() bool func (pos Position) String() string type Scanner Scanner用于从io.Reader中读取Unicode字符或词法单元 func (s *Scanner) Init(src io.Reader) *Scanner func (s *Scanner) Next() rune func (s *Scanner) Peek() rune func (s *Scanner) Pos() (pos Position) func (s *Scanner) Scan() rune func (s *Scanner) TokenText() string