lucene/expressions/src/java/org/apache/lucene/expressions/js/JavascriptParserErrorStrategy.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.lucene.expressions.js;


import java.text.ParseException;

import org.antlr.v4.runtime.DefaultErrorStrategy;
import org.antlr.v4.runtime.InputMismatchException;
import org.antlr.v4.runtime.NoViableAltException;
import org.antlr.v4.runtime.Parser;
import org.antlr.v4.runtime.RecognitionException;
import org.antlr.v4.runtime.Token;

/**
 * Allows for proper error handling in the ANTLR 4 parser
 */
class JavascriptParserErrorStrategy extends DefaultErrorStrategy {
  /**
   * Ensures the ANTLR parser will throw an exception after the first error
   *
   * @param recognizer the parser being used
   * @param re the original exception from the parser
   */
  @Override
  public void recover(Parser recognizer, RecognitionException re) {
    Token token = re.getOffendingToken();
    String message;

    if (token == null) {
      message = "error " + getTokenErrorDisplay(token);
    } else if (re instanceof InputMismatchException) {
       message = "unexpected token " + getTokenErrorDisplay(token) +
           " on line (" + token.getLine() + ") position (" + token.getCharPositionInLine() + ")" +
           " was expecting one of " + re.getExpectedTokens().toString(recognizer.getVocabulary());
    } else if (re instanceof NoViableAltException) {
      if (token.getType() == JavascriptParser.EOF) {
        message = "unexpected end of expression";
      } else {
        message = "invalid sequence of tokens near " + getTokenErrorDisplay(token) +
            " on line (" + token.getLine() + ") position (" + token.getCharPositionInLine() + ")";
      }
    } else {
      message = " unexpected token near " + getTokenErrorDisplay(token) +
          " on line (" + token.getLine() + ") position (" + token.getCharPositionInLine() + ")";
    }

    ParseException parseException = new ParseException(message, token.getStartIndex());
    parseException.initCause(re);
    throw new RuntimeException(parseException);
  }

  /**
   * Ensures the ANTLR parser will throw an exception after the first error
   *
   * @param recognizer the parser being used
   * @return no actual return value
   * @throws RecognitionException not used as a ParseException wrapped in a RuntimeException is thrown instead
   */
  @Override
  public Token recoverInline(Parser recognizer) throws RecognitionException {
    Token token = recognizer.getCurrentToken();
    String message = "unexpected token " + getTokenErrorDisplay(token) +
        " on line (" + token.getLine() + ") position (" + token.getCharPositionInLine() + ")" +
        " was expecting one of " + recognizer.getExpectedTokens().toString(recognizer.getVocabulary());
    ParseException parseException = new ParseException(message, token.getStartIndex());
    throw new RuntimeException(parseException);
  }

  /**
   * Do not allow syncing after errors to ensure the ANTLR parser will throw an exception
   *
   * @param recognizer the parser being used
   */
  @Override
  public void sync(Parser recognizer) {
  }
}