func (s *Scanner) Next() rune {

	s.b.Reset()

	ch := s.next()

	for unicode.IsSpace(ch) {
		ch = s.next()
	}

	tok := ch

	switch {

	default:
		tok = Undefined
		ch = s.next()

	case ch == EOF:
		break

	case isOperator(ch):
		tok = Operator
		ch = s.scanOperator(ch)

	case isDelimiter(ch):
		tok = Delimiter
		s.b.WriteRune(ch)
		ch = s.next()

	case isNameDelimiter(ch):
		tok = IdentifierDelimiter
		s.b.WriteRune(ch)
		ch = s.next()

	case isIdentifier(ch):
		tok = Identifier
		s.b.WriteRune(ch)
		ch = s.scanAlpha()

	case isSingleQuote(ch):
		tok = String
		ch = s.scanQuotedIdentifier(ch)

	case isDoubleQuote(ch):
		tok = QuotedIdentifier
		ch = s.scanQuotedIdentifier(ch)

	case isQuestionMark(ch):
		tok = Variable
		ch = s.next()

	case isColon(ch):
		ch = s.peek()
		if isDigit(ch) {
			tok = PosVariable
			ch = s.scanNumeric()
		} else {
			tok = NamedVariable
			ch = s.scanAlpha()
		}

	case isNumber(ch):
		tok = Number
		ch = s.scanNumber()
	}

	s.ch = ch
	s.rd.UnreadRune()

	if ch == Error {
		return ch
	}

	return tok
}
func (s *Scanner) Next() rune {

	s.b.Reset()

	ch := s.next()

	for unicode.IsSpace(ch) {
		ch = s.next()
	}

	tok := ch

	switch {

	default:
		tok = Undefined
		ch = s.next()

	case ch == EOF:
		break

	case isOperator(ch):
		tok = Operator
		ch = s.scanOperator(ch)

	case isDelimiter(ch):
		tok = Delimiter
		s.b.WriteRune(ch)
		ch = s.next()

	case isNameDelimiter(ch):
		tok = IdentifierDelimiter
		s.b.WriteRune(ch)
		ch = s.next()

	case isIdentifier(ch):
		tok = Identifier
		s.b.WriteRune(ch)
		ch = s.scanAlpha()

	case isSingleQuote(ch):
		tok = String
		ch = s.scanQuotedIdentifier(ch)

	case isDoubleQuote(ch):
		tok = QuotedIdentifier
		ch = s.scanQuotedIdentifier(ch)

	case isQuestionMark(ch):
		tok = Variable
		ch = s.next()

	case isColon(ch):
		ch = s.peek()
		if isDigit(ch) {
			tok = PosVariable
			ch = s.scanNumeric()
		} else {
			tok = NamedVariable
			ch = s.scanAlpha()
		}

	case isNumber(ch):
		tok = Number
		ch = s.scanNumber()
	}

	s.ch = ch
	s.rd.UnreadRune()

	if ch == Error {
		return ch
	}

	return tok
}
func ( s * Scanner ) Next ( ) rune { s . b . Reset ( ) ch := s . next ( ) for unicode . IsSpace ( ch ) { ch = s . next ( ) } tok := ch switch { default : tok = Undefined ch = s . next ( ) case ch == EOF : break case isOperator ( ch ) : tok = Operator ch = s . scanOperator ( ch ) case isDelimiter ( ch ) : tok = Delimiter s . b . WriteRune ( ch ) ch = s . next ( ) case isNameDelimiter ( ch ) : tok = IdentifierDelimiter s . b . WriteRune ( ch ) ch = s . next ( ) case isIdentifier ( ch ) : tok = Identifier s . b . WriteRune ( ch ) ch = s . scanAlpha ( ) case isSingleQuote ( ch ) : tok = String ch = s . scanQuotedIdentifier ( ch ) case isDoubleQuote ( ch ) : tok = QuotedIdentifier ch = s . scanQuotedIdentifier ( ch ) case isQuestionMark ( ch ) : tok = Variable ch = s . next ( ) case isColon ( ch ) : ch = s . peek ( ) if isDigit ( ch ) { tok = PosVariable ch = s . scanNumeric ( ) } else { tok = NamedVariable ch = s . scanAlpha ( ) } case isNumber ( ch ) : tok = Number ch = s . scanNumber ( ) } s . ch = ch s . rd . UnreadRune ( ) if ch == Error { return ch } return tok }
// Next returns the next Token.
Next returns the next Token .