AntlrParser.java 文件源码

/**
 * Parses the expression using antlr, aborts the parsing on the first error.
 *
 * @param expression
 *            an expression, not {@code null}
 * @return a {@link ParseTree} for further processing
 * @throws ExpressionException
 */
ParseTree parseExpression(String expression) throws ExpressionException {
    if (expression == null) {
        throw new IllegalArgumentException("expression must not be null");
    }
    ANTLRInputStream in = new ANTLRInputStream(expression);
    FunctionExpressionLexer lexer = new CapitulatingFunctionExpressionLexer(in);
    CommonTokenStream tokens = new CommonTokenStream(lexer);
    FunctionExpressionParser parser = new FunctionExpressionParser(tokens);

    parser.removeErrorListeners();
    lexer.removeErrorListeners();
    ExpressionErrorListener listener = new ExpressionErrorListener();
    parser.addErrorListener(listener);
    lexer.addErrorListener(listener);
    parser.setErrorHandler(new CapitulatingErrorStrategy());

    try {
        ParseTree tree = parser.operationExp();
        if (listener.containsError()) {
            throw new ExpressionException(listener.getErrorMessage(), listener.getErrorLine());
        } else {
            return tree;
        }
    } catch (CapitulatingRuntimeException e) {
        if (listener.containsError()) {
            throw new ExpressionException(listener.getErrorMessage(), listener.getErrorLine());
        } else {
            // cannot happen since the parser and lexer always register the error before trying
            // to recover
            throw new ExpressionException("Unknown error");
        }
    }

}