001/*
002 * Copyright (c) 2005 Einar Pehrson <einar@pehrson.nu>.
003 *
004 * This file is part of
005 * CleanSheets - a spreadsheet application for the Java platform.
006 *
007 * CleanSheets is free software; you can redistribute it and/or modify
008 * it under the terms of the GNU General Public License as published by
009 * the Free Software Foundation; either version 2 of the License, or
010 * (at your option) any later version.
011 *
012 * CleanSheets is distributed in the hope that it will be useful,
013 * but WITHOUT ANY WARRANTY; without even the implied warranty of
014 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
015 * GNU General Public License for more details.
016 *
017 * You should have received a copy of the GNU General Public License
018 * along with CleanSheets; if not, write to the Free Software
019 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
020 */
021package csheets.core.formula;
022
023import java.util.SortedSet;
024
025import csheets.core.Cell;
026import csheets.core.Value;
027
028/**
029 * A reference to one or more cells in a spreadsheet.
030 * @author Einar Pehrson
031 */
032public interface Reference extends Expression, Comparable<Reference> {
033
034        public Value evaluate();
035
036        /**
037         * Returns the cell addresses (or address) that the reference points to.
038         * @return a naturally ordered set of the references' addresses
039         */
040        public SortedSet<Cell> getCells();
041
042        /**
043         * Compares the reference with the given reference for order.
044         * @param reference the reference to be compared
045         * @return a negative integer, zero, or a positive integer as this object is less than, equal to, or greater than the specified object.
046         */
047        public int compareTo(Reference reference);
048}