/*  OpeningBook - Interface to define the functionality of a opening book.  Copyright (C) 2003 The Java-Chess team <info@java-chess.de>  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 2  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, write to the Free Software  Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.*/ package de.java_chess.javaChess.engine.opening_book;import antlr.*;import de.java_chess.javaChess.ply.*;import java.io.File;import java.io.IOException;/** * This interface defines the functionality of a opening book. */public interface OpeningBook {    // Methods    /**     * Advance the game by one user ply.     *     * @param ply The ply from the user.     */    void doUserPly( Ply ply);    /**     * Get the next ply from the opening book, if there is     * one available, or null if not.     *     * @return The next ply from the opening book, or null      *         if there's no ply available.     */    AnalyzedPly getOpeningBookPly();    /**     * Reset the opening book to the initial piece position.     */    void reset();    /**     * Add a opening in PGN format to the opening book and return     * the error status.     *     * @param file The File to add to the opening book.     */    void addPGNopening( File file);}