/*
 * Copyright 1999-2006 Sun Microsystems, Inc.  All Rights Reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Sun designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Sun in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
 * CA 95054 USA or visit www.sun.com if you need additional information or
 * have any questions.
 */

package java.util.regex;

import sun.security.action.GetPropertyAction;


/**
 * Unchecked exception thrown to indicate a syntax error in a
 * regular-expression pattern.
 *
 * @author  unascribed
 * @since 1.4
 * @spec JSR-51
 */

public class PatternSyntaxException
    extends IllegalArgumentException
{

    private final String desc;
    private final String pattern;
    private final int index;

    /**
     * Constructs a new instance of this class.
     *
     * @param  desc
     *         A description of the error
     *
     * @param  regex
     *         The erroneous pattern
     *
     * @param  index
     *         The approximate index in the pattern of the error,
     *         or <tt>-1</tt> if the index is not known
     */
    public PatternSyntaxException(String desc, String regex, int index) {
        this.desc = desc;
        this.pattern = regex;
        this.index = index;
    }

    /**
     * Retrieves the error index.
     *
     * @return  The approximate index in the pattern of the error,
     *         or <tt>-1</tt> if the index is not known
     */
    public int getIndex() {
        return index;
    }

    /**
     * Retrieves the description of the error.
     *
     * @return  The description of the error
     */
    public String getDescription() {
        return desc;
    }

    /**
     * Retrieves the erroneous regular-expression pattern.
     *
     * @return  The erroneous pattern
     */
    public String getPattern() {
        return pattern;
    }

    private static final String nl =
        java.security.AccessController
            .doPrivileged(new GetPropertyAction("line.separator"));

    /**
     * Returns a multi-line string containing the description of the syntax
     * error and its index, the erroneous regular-expression pattern, and a
     * visual indication of the error index within the pattern.
     *
     * @return  The full detail message
     */
    public String getMessage() {
        StringBuffer sb = new StringBuffer();
        sb.append(desc);
        if (index >= 0) {
            sb.append(" near index ");
            sb.append(index);
        }
        sb.append(nl);
        sb.append(pattern);
        if (index >= 0) {
            sb.append(nl);
            for (int i = 0; i < index; i++) sb.append(' ');
            sb.append('^');
        }
        return sb.toString();
    }

}