Package org.antlr.v4.runtime

Interface TokenSource

  • All Known Implementing Classes:
    Lexer, LexerInterpreter, ListTokenSource, XPathLexer
    public interface TokenSource
    A source of tokens must provide a sequence of tokens via nextToken() and also must reveal it's source of characters; CommonToken's text is computed from a CharStream; it only store indices into the char stream.

    Errors from the lexer are never passed to the parser. Either you want to keep going or you do not upon token recognition error. If you do not want to continue lexing then you do not want to continue parsing. Just throw an exception not under RecognitionException and Java will naturally toss you all the way out of the recognizers. If you want to continue lexing then you should not throw an exception to the parser--it has already requested a token. Keep lexing until you get a valid one. Just report errors and keep going, looking for a valid token.

    • Method Detail

      • nextToken

        Token nextToken()
        Return a Token object from your input stream (usually a CharStream). Do not fail/return upon lexing error; keep chewing on the characters until you get a good one; errors are not passed through to the parser.

      • getLine

        int getLine()
        Get the line number for the current position in the input stream. The first line in the input is line 1.
        Returns:
        The line number for the current position in the input stream, or 0 if the current token source does not track line numbers.

      • getCharPositionInLine

        int getCharPositionInLine()
        Get the index into the current line for the current position in the input stream. The first character on a line has position 0.
        Returns:
        The line number for the current position in the input stream, or -1 if the current token source does not track character positions.

      • getInputStream

        CharStream getInputStream()
        Get the CharStream from which this token source is currently providing tokens.
        Returns:
        The CharStream associated with the current position in the input, or null if no input stream is available for the token source.

      • getSourceName

        String getSourceName()
        Gets the name of the underlying input source. This method returns a non-null, non-empty string. If such a name is not known, this method returns IntStream.UNKNOWN_SOURCE_NAME.

      • setTokenFactory

        void setTokenFactory​(TokenFactory<?> factory)
        Set the TokenFactory this token source should use for creating Token objects from the input.
        Parameters:
        factory - The TokenFactory to use for creating tokens.

      • getTokenFactory

        TokenFactory<?> getTokenFactory()
        Gets the TokenFactory this token source is currently using for creating Token objects from the input.
        Returns:
        The TokenFactory currently used by this token source.