/* ====================================================================   Copyright 2003-2004   Apache Software Foundation   Licensed 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.poi.hssf.record.formula;/** * defines a Ptg that is an operation instead of an operand * @author  andy */public abstract class OperationPtg extends Ptg{    public final static int TYPE_UNARY    = 0;    public final static int TYPE_BINARY   = 1;    public final static int TYPE_FUNCTION = 2;    public abstract int getType();        /**     *  returns a string representation of the operations     *  the length of the input array should equal the number returned by      *  @see #getNumberOfOperands     *       */    public abstract String toFormulaString(String[] operands);        /**     * The number of operands expected by the operations     */    public abstract int getNumberOfOperands();        public byte getDefaultOperandClass() {return Ptg.CLASS_VALUE;}    }