@Test
public void expressionRule() throws Exception {
    DefaultJtwigParserConfiguration config = new DefaultJtwigParserConfiguration();
    ParserContext context = ParserContext.instance(
            ResourceReference.inline("Hello"),
            config,
            config.getAddonParserProviders(),
            config.getUnaryOperators(),
            config.getBinaryOperators(),
            config.getTestExpressionParsers()
    );

    MapSelectionExpressionParser parser = context.parser(MapSelectionExpressionParser.class);

    TracingParseRunner<Expression> runner = new TracingParseRunner<>(parser.ExpressionRule());
    ParsingResult<Expression> result = runner.run("list[position.size]");
    Expression resultValue = result.resultValue;

    System.out.println(resultValue);
}
 

/** Like {@link #toJavaRegex(String)}, but for debugging. */
@SuppressWarnings("unused") // leaving here for future debugging.
@Nonnull
static String debugToJavaRegex(String regex) {
  GroupWildcard parser = Parboiled.createParser(GroupWildcard.class);
  TracingParseRunner<String> runner =
      new TracingParseRunner<String>(parser.TopLevel()).withLog(new StringBuilderSink());
  ParsingResult<String> result = runner.run(regex);
  if (!result.matched) {
    throw new IllegalArgumentException("Unhandled input: " + regex + "\n" + runner.getLog());
  }
  return result.resultValue;
}
 

/** Like {@link #convertToJavaRegex(String)}, but for debugging. */
@SuppressWarnings("unused") // leaving here for future debugging.
@Nonnull
static String debugConvertToJavaRegex(String regex) {
  AsPathRegex parser = Parboiled.createParser(AsPathRegex.class);
  TracingParseRunner<String> runner =
      new TracingParseRunner<String>(parser.TopLevel()).withLog(new StringBuilderSink());
  ParsingResult<String> result = runner.run(regex);
  if (!result.matched) {
    throw new IllegalArgumentException("Unhandled input: " + regex + "\n" + runner.getLog());
  }
  return result.resultValue;
}
 

TestBase() {
    parser = Parboiled.createParser(CfgPropsParboiled.class);
    tracingRunner = new TracingParseRunner(parser.cfgProps());
    reportingRunner = new ReportingParseRunner(parser.cfgProps());
}
 

private TracingParseRunner<J> getTracingParseRunner() {
	Rule parserRootRule = getParserRootRule();
	TracingParseRunner<J> runner = new TracingParseRunner<>(parserRootRule);
	return runner;
}