Walker.java 文件源码

private void setupPicky(PainlessParser parser) {
    // Diagnostic listener invokes syntaxError on other listeners for ambiguity issues,
    parser.addErrorListener(new DiagnosticErrorListener(true));
    // a second listener to fail the test when the above happens.
    parser.addErrorListener(new BaseErrorListener() {
        @Override
        public void syntaxError(final Recognizer<?,?> recognizer, final Object offendingSymbol, final int line,
                                final int charPositionInLine, final String msg, final RecognitionException e) {
            throw new AssertionError("line: " + line + ", offset: " + charPositionInLine +
                ", symbol:" + offendingSymbol + " " + msg);
        }
    });

    // Enable exact ambiguity detection (costly). we enable exact since its the default for
    // DiagnosticErrorListener, life is too short to think about what 'inexact ambiguity' might mean.
    parser.getInterpreter().setPredictionMode(PredictionMode.LL_EXACT_AMBIG_DETECTION);
}