StringTemplate.java 文件源码

public static StringTemplate fromString(String pattern) {
    class DescriptiveErrorListener extends BaseErrorListener {
        public List<String> errors = new ArrayList<>();

        @Override
        public void syntaxError(Recognizer<?, ?> recognizer, Object offendingSymbol,
                                int line, int charPositionInLine,
                                String msg, RecognitionException e) {
            errors.add(String.format("%d:%d: %s", line, charPositionInLine, msg));
        }
    }

    final DescriptiveErrorListener error_listener = new DescriptiveErrorListener();

    final StringSubstitutionLexer lexer = new StringSubstitutionLexer(CharStreams.fromString(pattern));
    lexer.removeErrorListeners();
    lexer.addErrorListener(error_listener);
    final StringSubstitutionParser parser = new StringSubstitutionParser(new UnbufferedTokenStream(lexer));
    parser.removeErrorListeners();
    parser.addErrorListener(error_listener);

    parser.setErrorHandler(new BailErrorStrategy());
    final StringSubstitutionParser.ExprContext result = parser.expr();
    if (result.exception != null)
        throw new IllegalArgumentException("errors during parsing: " + pattern, result.exception);
    else if (!error_listener.errors.isEmpty())
        throw new IllegalArgumentException("syntax errors during parsing:\n" + String.join("\n", error_listener.errors.stream().map(s -> "  " + s).collect(Collectors.toList())));
    return result.s;
}