001/*
002 * Copyright (c) 2012-2017 Institut National des Sciences Appliquées de Lyon (INSA-Lyon)
003 *
004 * All rights reserved. This program and the accompanying materials
005 * are made available under the terms of the Eclipse Public License v1.0
006 * which accompanies this distribution, and is available at
007 * http://www.eclipse.org/legal/epl-v10.html
008 */
009package org.eclipse.golo.compiler.parser;
010
011import static gololang.Messages.message;
012
013/**
014 * This exception is thrown when parse errors are encountered.
015 * You can explicitly create objects of this exception type by
016 * calling the method generateParseException in the generated
017 * parser.
018 *
019 * You can modify this class to customize your error reporting
020 * mechanisms so long as you retain the public fields.
021 */
022public class ParseException extends Exception {
023
024  /**
025   * The version identifier for this Serializable class.
026   * Increment only if the <i>serialized</i> form of the
027   * class changes.
028   */
029  private static final long serialVersionUID = 1L;
030
031  /**
032   * The end of line string for this machine.
033   */
034  protected static String EOL = System.getProperty("line.separator", "\n");
035
036  /**
037   * This constructor is used by the method "generateParseException"
038   * in the generated parser.  Calling this constructor generates
039   * a new object of this type with the fields "currentToken",
040   * "expectedTokenSequences", and "tokenImage" set.
041   */
042  public ParseException(Token currentTokenVal,
043                        int[][] expectedTokenSequencesVal,
044                        String[] tokenImageVal
045  ) {
046    super(initialise(currentTokenVal, expectedTokenSequencesVal, tokenImageVal));
047    currentToken = currentTokenVal;
048    expectedTokenSequences = expectedTokenSequencesVal;
049    tokenImage = tokenImageVal;
050  }
051
052  /**
053   * The following constructors are for use by you for whatever
054   * purpose you can think of.  Constructing the exception in this
055   * manner makes the exception behave in the normal way - i.e., as
056   * documented in the class "Throwable".  The fields "errorToken",
057   * "expectedTokenSequences", and "tokenImage" do not contain
058   * relevant information.  The JavaCC generated code does not use
059   * these constructors.
060   */
061
062  public ParseException() {
063    super();
064  }
065
066  /**
067   * Constructor with message.
068   */
069  public ParseException(String message) {
070    super(message);
071  }
072
073
074  /**
075   * This is the last token that has been consumed successfully.  If
076   * this object has been created due to a parse error, the token
077   * followng this token will (therefore) be the first error token.
078   */
079  public Token currentToken;
080
081  /**
082   * Each entry in this array is an array of integers.  Each array
083   * of integers represents a sequence of tokens (by their ordinal
084   * values) that is expected at this point of the parse.
085   */
086  public int[][] expectedTokenSequences;
087
088  /**
089   * This is a reference to the "tokenImage" array of the generated
090   * parser within which the parse error occurred.  This array is
091   * defined in the generated ...Constants interface.
092   */
093  public String[] tokenImage;
094
095  /**
096   * It uses "currentToken" and "expectedTokenSequences" to generate a parse
097   * error message and returns it.  If this object has been created
098   * due to a parse error, and you do not catch it (it gets thrown
099   * from the parser) the correct error message
100   * gets displayed.
101   */
102  private static String initialise(Token currentToken,
103                                   int[][] expectedTokenSequences,
104                                   String[] tokenImage) {
105
106    StringBuffer expected = new StringBuffer();
107    int maxSize = 0;
108    for (int i = 0; i < expectedTokenSequences.length; i++) {
109      if (maxSize < expectedTokenSequences[i].length) {
110        maxSize = expectedTokenSequences[i].length;
111      }
112      for (int j = 0; j < expectedTokenSequences[i].length; j++) {
113        expected.append(tokenImage[expectedTokenSequences[i][j]]).append(' ');
114      }
115      if (expectedTokenSequences[i][expectedTokenSequences[i].length - 1] != 0) {
116        expected.append("...");
117      }
118      expected.append(EOL).append("    ");
119    }
120    String retval = message("unexpected_token");
121    Token tok = currentToken.next;
122    for (int i = 0; i < maxSize; i++) {
123      if (i != 0) retval += " ";
124      if (tok.kind == 0) {
125        retval += tokenImage[0];
126        break;
127      }
128      retval += " " + tokenImage[tok.kind];
129      retval += " `";
130      retval += add_escapes(tok.image);
131      retval += "` ";
132      tok = tok.next;
133    }
134    retval += message("source_position", currentToken.next.beginLine, currentToken.next.beginColumn);
135
136    return retval;
137  }
138
139  /**
140   * Used to convert raw characters to their escaped version
141   * when these raw version cannot be used as part of an ASCII
142   * string literal.
143   */
144  static String add_escapes(String str) {
145    StringBuffer retval = new StringBuffer();
146    char ch;
147    for (int i = 0; i < str.length(); i++) {
148      switch (str.charAt(i)) {
149        case '\b':
150          retval.append("\\b");
151          continue;
152        case '\t':
153          retval.append("\\t");
154          continue;
155        case '\n':
156          retval.append("\\n");
157          continue;
158        case '\f':
159          retval.append("\\f");
160          continue;
161        case '\r':
162          retval.append("\\r");
163          continue;
164        case '\"':
165          retval.append("\\\"");
166          continue;
167        case '\'':
168          retval.append("\\\'");
169          continue;
170        case '\\':
171          retval.append("\\\\");
172          continue;
173        default:
174          if ((ch = str.charAt(i)) < 0x20 || ch > 0x7e) {
175            String s = "0000" + Integer.toString(ch, 16);
176            retval.append("\\u" + s.substring(s.length() - 4, s.length()));
177          } else {
178            retval.append(ch);
179          }
180          continue;
181      }
182    }
183    return retval.toString();
184  }
185
186}