java/engine/org/apache/derby/impl/sql/compile/ParseException.java

/*

   Derby - Class org.apache.derby.impl.sql.compile.ParseException

   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.derby.impl.sql.compile;

/**
 * This exception is thrown when parse errors are encountered.
 * You can explicitly create objects of this exception type by
 * calling the method generateParseException in the generated
 * parser.
 *
 * You can modify this class to customize your error reporting
 * mechanisms so long as you retain the public fields.
 */
class ParseException extends Exception {

  /**
   * This constructor is used by the method "generateParseException"
   * in the generated parser.  Calling this constructor generates
   * a new object of this type with the fields "currentToken",
   * "expectedTokenSequences", and "tokenImage" set.  The boolean
   * flag "specialConstructor" is also set to true to indicate that
   * this constructor was used to create this object.
   * This constructor calls its super class with the empty string
   * to force the "toString" method of parent class "Throwable" to
   * print the error message in the form:
   *     ParseException: <result of getMessage>
   */
  public ParseException(Token currentTokenVal,
                        int[][] expectedTokenSequencesVal,
                        String[] tokenImageVal
                       )
  {
    super("");
    specialConstructor = true;
    currentToken = currentTokenVal;
    expectedTokenSequences = expectedTokenSequencesVal;
    tokenImage = tokenImageVal;
  }

  /**
   * The following constructors are for use by you for whatever
   * purpose you can think of.  Constructing the exception in this
   * manner makes the exception behave in the normal way - i.e., as
   * documented in the class "Throwable".  The fields "errorToken",
   * "expectedTokenSequences", and "tokenImage" do not contain
   * relevant information.  The JavaCC generated code does not use
   * these constructors.
   */

  public ParseException() {
    super();
    specialConstructor = false;
  }

  public ParseException(String message) {
    super(message);
    specialConstructor = false;
  }

  /**
   * This variable determines which constructor was used to create
   * this object and thereby affects the semantics of the
   * "getMessage" method (see below).
   */
  protected boolean specialConstructor;

  /**
   * This is the last token that has been consumed successfully.  If
   * this object has been created due to a parse error, the token
   * followng this token will (therefore) be the first error token.
   */
  public Token currentToken;

  /**
   * Each entry in this array is an array of integers.  Each array
   * of integers represents a sequence of tokens (by their ordinal
   * values) that is expected at this point of the parse.
   */
  public int[][] expectedTokenSequences;

  /**
   * This is a reference to the "tokenImage" array of the generated
   * parser within which the parse error occurred.  This array is
   * defined in the generated ...Constants interface.
   */
  public String[] tokenImage;

  /**
   * This method has the standard behavior when this object has been
   * created using the standard constructors.  Otherwise, it uses
   * "currentToken" and "expectedTokenSequences" to generate a parse
   * error message and returns it.  If this object has been created
   * due to a parse error, and you do not catch it (it gets thrown
   * from the parser), then this method is called during the printing
   * of the final stack trace, and hence the correct error message
   * gets displayed.
   */
  @Override
  public String getMessage() {
    if (!specialConstructor) {
      return super.getMessage();
    }
    String expected = "";
    int maxSize = 0;
    for (int i = 0; i < expectedTokenSequences.length; i++) {
      if (maxSize < expectedTokenSequences[i].length) {
        maxSize = expectedTokenSequences[i].length;
      }
      for (int j = 0; j < expectedTokenSequences[i].length; j++) {
        expected += tokenImage[expectedTokenSequences[i][j]] + " ";
      }
      if (expectedTokenSequences[i][expectedTokenSequences[i].length - 1] != 0) {
        expected += "...";
      }
      expected += eol + "    ";
    }
    String retval = "Encountered \"";
    Token tok = currentToken.next;
    for (int i = 0; i < maxSize; i++) {
      if (i != 0) retval += " ";
      if (tok.kind == 0) {
        retval += tokenImage[0];
        break;
      }
      retval += add_escapes(tok.image);
      tok = tok.next;
    }
    retval += "\" at line " + currentToken.next.beginLine + ", column " + currentToken.next.beginColumn;
 /*
  * For output compatibility with previous releases, do not report expected tokens.
  *
    retval += "." + eol;
    if (expectedTokenSequences.length == 1) {
      retval += "Was expecting:" + eol + "    ";
    } else {
      retval += "Was expecting one of:" + eol + "    ";
    }
    retval += expected;
  */
    return retval;
  }

  /**
   * The end of line string for this machine.
   */
  protected String eol = System.getProperty("line.separator", "\n");

  /**
   * Used to convert raw characters to their escaped version
   * when these raw version cannot be used as part of an ASCII
   * string literal.
   */
  protected String add_escapes(String str) {
      StringBuilder retval = new StringBuilder();
      char ch;
      for (int i = 0; i < str.length(); i++) {
        switch (str.charAt(i))
        {
           case 0 :
              continue;
           case '\b':
              retval.append("\\b");
              continue;
           case '\t':
              retval.append("\\t");
              continue;
           case '\n':
              retval.append("\\n");
              continue;
           case '\f':
              retval.append("\\f");
              continue;
           case '\r':
              retval.append("\\r");
              continue;
           case '\"':
              retval.append("\\\"");
              continue;
           case '\'':
              retval.append("\\\'");
              continue;
           case '\\':
              retval.append("\\\\");
              continue;
           default:
              if ((ch = str.charAt(i)) < 0x20 || ch > 0x7e) {
                 String s = "0000" + Integer.toString(ch, 16);
                 retval.append("\\u");
                 retval.append(s.substring(s.length() - 4, s.length()));
              } else {
                 retval.append(ch);
              }
              continue;
        }
      }
      return retval.toString();
   }

}