org.vesalainen.parser.util.Recoverable Maven / Gradle / Ivy

Go to download

Show more of this group Show more artifacts with this name
Show all versions of lpg Show documentation

Java Lookahead Parser Generator. Generator produces LALR(k) parsers. Grammar rules are entered using annotations. Rule annotation can be attached to reducer method, which keeps rule and it's action together.

The newest version!

/*
 * Copyright (C) 2014 Timo Vesalainen
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program 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 for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see .
 */

package org.vesalainen.parser.util;

import java.io.IOException;

/**
 * Recoverable is an interface used by the parser. In case of syntax error or
 * other problem while parsing, the parser check the existence of method 
 * annotated with @RecoverMethod. If the method exist it is called. 
 * 
 * If @RecoverMethod
 * doesn't exist, InputReader searches for InputStream or Reader class implementing
 * Recoverable interface. If found it calls it's recover method. If the method return's
 * true the parser continues at the start of the grammar. If it return's false it throws
 * exception.
 * 
 * 
Note that parser often encloses input which practically hides the Recoverable input. If
 * that happens, a warning is printed to stderr during compilation.
 * 
 * In most cases using @RecoverMethod is easier. 
 * 
 * @author Timo Vesalainen
 */
public interface Recoverable
{
    /**
     * If returns true, the parser is able to continue parsing in grammar start.
     * @param msg Error message
     * @param source Error source
     * @param line Line number in source
     * @param column Column number
     * @return 
     * @throws java.io.IOException 
     */
   boolean recover(String msg, String source, int line, int column) throws IOException; 
}