DescriptiveErrorStrategy.java 文件源码

protected String createNoViableAlternativeErrorMessage(Parser recognizer, NoViableAltException e) {
    TokenStream tokens = recognizer.getInputStream();
    String input;
    if (tokens != null) {
        if (e.getStartToken().getType() == Token.EOF) {
            input = "<EOF>";
        } else {
            input = charStream.getText(Interval.of(e.getStartToken().getStartIndex(), e.getOffendingToken().getStopIndex()));
        }
    } else {
        input = "<unknown input>";
    }

    return "Unexpected input: " + escapeWSAndQuote(input);
}