Ejemplo n.º 1
0
func (s *Scanner) scanNumber() *token.Token {
	start := s.chOffset
	for s.isDigit(s.ch) {
		s.next()
	}
	return token.NewToken(token.NUMBER, string(s.src[start:s.chOffset]))
}
Ejemplo n.º 2
0
func (s *Scanner) Next() (tok *token.Token) {
next:
	if s.savedTok != nil {
		tok = s.savedTok
		s.savedTok = nil
	} else {
		s.skipWhitespace()

		switch ch := s.ch; {
		case s.isLetter(ch):
			tok = s.scanName()
		case s.isDigit(ch):
			tok = s.scanNumber()
		case ch == '"':
			tok = s.scanStringConst()
		case ch == '\n':
			s.state = maybesemi
			goto next
		default:
			tok = s.scanOperator(ch)
		}

		switch s.state {
		case maybeinsert:
			if isDoStart(tok) {
				s.savedTok = tok
				tok = token.NewToken(token.DO, "do")
				s.state = normal
			} else if !isCommandEnd(tok) {
				s.state = normal
			}
		case maybesemi:
			if isSemiStart(tok) {
				s.savedTok = tok
				tok = token.NewToken(token.SEMICOLON, ";")
			}
			s.state = normal
		case normal:
			if isCommandEnd(tok) {
				s.state = maybeinsert
			}
		}
	}

	return
}
Ejemplo n.º 3
0
func (s *Scanner) scanStringConst() *token.Token {
	start := s.offset - 1
	s.next()
	for s.ch != '"' {
		s.next()
	}
	s.next()
	return token.NewToken(token.STRINGCONST, string(s.src[start:s.chOffset]))
}
Ejemplo n.º 4
0
func (s *Scanner) scanName() *token.Token {
	// 2.1.2 Hardware Conventions and Preprocessor Rules
	// (a)

	// (1) A name is either a single small letter or a sequence of letters
	// and digits starting with a capital letter. The character immediately
	// following a name may not be a letter or a digit.
	start := s.chOffset
	for s.isLetter(s.ch) || s.isDigit(s.ch) {
		s.next()
	}
	str := s.src[start:s.chOffset]

	// (2) A sequence of two or more small letters which is not part of a NAME,
	// SECTBRA, SECTKET or STRINGCONST is a reserved system word and may be used
	// to represent a canonical symbol.
	kind := token.NAME
	literal := string(str)
	if len(str) > 1 {
		kind = token.LookupName(literal)
	}
	return token.NewToken(kind, literal)
}
Ejemplo n.º 5
0
func (s *Scanner) scanOperator(ch rune) *token.Token {
	kind := token.ILLEGAL
	lit := string(ch)
	s.next()

	switch ch {
	case '/':
		if s.ch == '/' {
			s.next()
			kind, lit = token.COMMENT, s.scanComment()
		} else {
			kind = token.DIV
		}
	case '+':
		kind, lit = token.PLUS, "+"
	case '-':
		if s.ch == '>' {
			s.next()
			kind, lit = token.COND, "->"
		} else {
			kind = token.MINUS
		}
	case '=':
		kind = token.EQ
	case '!':
		if s.ch == '=' {
			s.next()
			kind, lit = token.NE, "!="
		} else {
			kind = token.NOT
		}
	case '<':
		switch s.ch {
		case '=':
			s.next()
			kind, lit = token.LE, "<="
		case '<':
			s.next()
			kind, lit = token.LSHIFT, "<<"
		default:
			kind = token.LS
		}
	case '>':
		switch s.ch {
		case '=':
			s.next()
			kind, lit = token.GE, ">="
		case '>':
			s.next()
			kind, lit = token.RSHIFT, ">>"
		default:
			kind = token.GR
		}
	case '&':
		kind = token.LOGAND
	case '|':
		kind = token.LOGOR
	case ',':
		kind = token.COMMA
	case ':':
		if s.ch == '=' {
			kind, lit = token.ASS, ":="
		} else {
			kind = token.COLON
		}
	case '$':
		switch s.ch {
		case '(':
			s.next()
			kind, lit = token.SECTBRA, "$("
		case ')':
			s.next()
			kind, lit = token.SECTKET, "$)"
		}
	case '(':
		kind = token.RBRA
	case ')':
		kind = token.RKET
	case '[':
		kind = token.SBRA
	case ']':
		kind = token.SKET
	case ';':
		kind = token.SEMICOLON
	case '*':
		kind = token.STAR
	case -1:
		kind, lit = token.EOF, ""
	}

	return token.NewToken(kind, lit)
}
Ejemplo n.º 6
0
		t.Errorf("bad token: got '%s', expected '%s'", tok, etok)
	}
}

func assertTokensEqualSource(t *testing.T, toks []*token.Token, str string) {
	var s Scanner
	s.Init([]byte(str))
	for _, etok := range toks {
		tok := s.Next()
		assertTokensEqual(t, tok, etok)
	}

}

var test_single_token = [...]*token.Token{
	token.NewToken(token.EOF, ""),
	token.NewToken(token.COMMENT, "// this is a BCPL a comment!\n"),

	// Names.
	token.NewToken(token.NAME, "Global"),
	token.NewToken(token.NAME, "Let"),
	token.NewToken(token.NAME, "a"),
	token.NewToken(token.NAME, "Z"),

	// Numbers.
	token.NewToken(token.NUMBER, "1"),
	token.NewToken(token.NUMBER, "98765"),

	// String constants.
	token.NewToken(token.STRINGCONST, "\"foo bar baz\n\""),