RELEASE_2_1_13/src/java/org/apache/cocoon/components/xpointer/parser/ParseException.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.cocoon.components.xpointer.parser;

/**
 * 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.
 */
public 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.
     */
    public String getMessage() {
        if (!specialConstructor) {
            return super.getMessage();
        }
        StringBuffer expected = new StringBuffer();
        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.append(tokenImage[expectedTokenSequences[i][j]]);
                expected.append(" ");
            }
            if (expectedTokenSequences[i][expectedTokenSequences[i].length - 1]
                != 0) {
                expected.append("...");
            }
            expected.append(eol);
            expected.append("    ");
        }
        StringBuffer retval = new StringBuffer("Encountered \"");
        Token tok = currentToken.next;
        for (int i = 0; i < maxSize; i++) {
            if (i != 0)
                retval.append(" ");
            if (tok.kind == 0) {
                retval.append(tokenImage[0]);
                break;
            }
            retval.append(add_escapes(tok.image));
            tok = tok.next;
        }
        retval.append("\" at line ");
        retval.append(currentToken.next.beginLine);
        retval.append(", column ");
        retval.append(currentToken.next.beginColumn);
        retval.append(".");
        retval.append(eol);
        retval.append("Was expecting");
        if (expectedTokenSequences.length != 1) {
            retval.append(" one of");
        }
        retval.append(":");
        retval.append(eol);
        retval.append("    ");
        retval.append(expected);
        return retval.toString();
    }

    /**
     * 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) {
        StringBuffer retval = new StringBuffer();
        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" + s.substring(s.length() - 4, s.length()));
                    } else {
                        retval.append(ch);
                    }
                    continue;
            }
        }
        return retval.toString();
    }

}