How to use

seek

method

in

org.antlr.v4.runtime.CommonTokenStream

private ParserRuleContext getParseTree(final String sql) {
 final SqlBaseLexer sqlBaseLexer = new SqlBaseLexer(
   new CaseInsensitiveStream(CharStreams.fromString(sql)));
 final CommonTokenStream tokenStream = new CommonTokenStream(sqlBaseLexer);
 final SqlBaseParser sqlBaseParser = new SqlBaseParser(tokenStream);
 sqlBaseLexer.removeErrorListeners();
 sqlBaseLexer.addErrorListener(ERROR_LISTENER);
 sqlBaseParser.removeErrorListeners();
 sqlBaseParser.addErrorListener(ERROR_LISTENER);
 final Function<SqlBaseParser, ParserRuleContext> parseFunction = SqlBaseParser::statements;
 try {
  // first, try parsing with potentially faster SLL mode
  sqlBaseParser.getInterpreter().setPredictionMode(PredictionMode.SLL);
  return parseFunction.apply(sqlBaseParser);
 } catch (final ParseCancellationException ex) {
  // if we fail, parse with LL mode
  tokenStream.seek(0); // rewind input stream
  sqlBaseParser.reset();
  sqlBaseParser.getInterpreter().setPredictionMode(PredictionMode.LL);
  return parseFunction.apply(sqlBaseParser);
 }
}

public void switchToFullLL() {
  // First rewind the token stream
  this.tokens.seek(0);
  // Use full (custom) error reporting now
  this.parser.setErrorHandler(new ErrorStrategy4());
  this.parser.addErrorListener(this);
  // Now try full LL(*)
  this.parser.getInterpreter().setPredictionMode(PredictionMode.LL);
}

private Node invokeParser(String name, String sql,
  Function<SqlBaseParser, ParserRuleContext> parseFunction) {
  try {
    SqlBaseLexer lexer = new SqlBaseLexer(
      new CaseInsensitiveStream(new ANTLRInputStream(sql)));
    CommonTokenStream tokenStream = new CommonTokenStream(lexer);
    SqlBaseParser parser = new SqlBaseParser(tokenStream);
    parser.addParseListener(new PostProcessor(Arrays.asList(parser.getRuleNames())));
    lexer.removeErrorListeners();
    lexer.addErrorListener(ERROR_LISTENER);
    parser.removeErrorListeners();
    parser.addErrorListener(ERROR_LISTENER);
    ParserRuleContext tree;
    try {
      // first, try parsing with potentially faster SLL mode
      parser.getInterpreter().setPredictionMode(PredictionMode.SLL);
      tree = parseFunction.apply(parser);
    } catch (ParseCancellationException ex) {
      // if we fail, parse with LL mode
      tokenStream.seek(0); // rewind input stream
      parser.reset();
      parser.getInterpreter().setPredictionMode(PredictionMode.LL);
      tree = parseFunction.apply(parser);
    }
    return new AstBuilder().visit(tree);
  } catch (StackOverflowError e) {
    throw new ParsingException(name + " is too large (stack overflow while parsing)");
  }
}

tokenStream.seek(0); // rewind input stream
parser.reset();

private ParseTree parse(LiquidLexer lexer) {
  lexer.removeErrorListeners();
  lexer.addErrorListener(new BaseErrorListener(){
    @Override
    public void syntaxError(Recognizer<?, ?> recognizer, Object offendingSymbol, int line, int charPositionInLine, String msg, RecognitionException e) {
      throw new RuntimeException(String.format("lexer error on line %s, index %s", line, charPositionInLine), e);
    }
  });
  CommonTokenStream tokens = new CommonTokenStream(lexer);
  LiquidParser parser = new LiquidParser(tokens);
  parser.removeErrorListeners();
  parser.addErrorListener(new BaseErrorListener(){
    @Override
    public void syntaxError(Recognizer<?, ?> recognizer, Object offendingSymbol, int line, int charPositionInLine, String msg, RecognitionException e) {
      throw new RuntimeException(String.format("parser error on line %s, index %s", line, charPositionInLine), e);
    }
  });
  
  parser.getInterpreter().setPredictionMode(PredictionMode.SLL);
  try {
    return parser.parse();
  } catch (Exception e) {
    tokens.seek(0);
    parser.reset();
    parser.getInterpreter().setPredictionMode(PredictionMode.LL);
    return parser.parse();
  }
}

this.tokens.seek(0);