001 /**
002 * JEP - Java Expression Parser JEP is a Java package for parsing and evaluating mathematical expressions. It currently supports user defined
003 * variables, constant, and functions. A number of common mathematical functions and constants are included. Author: Nathan Funk Copyright (C)
004 * 2000 Nathan Funk JEP is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as
005 * published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version. JEP is distributed in the
006 * hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
007 * PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with
008 * JEP; if not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
009 */
010
011 package jigcell.sbml2.jep.function;
012
013 import java.util.Stack;
014 import jigcell.sbml2.FunctionDefinition;
015
016 /**
017 * Function classes extend this class. It is an implementation of the PostfixMathCommandI interface.
018 *
019 * <p>
020 * It includes a numberOfParameters member, that is checked when parsing the expression. This member should be initialized to an appropriate
021 * value for all classes extending this class. If an arbitrary number of parameters should be allowed, initialize this member to -1.
022 * </p>
023 */
024
025 public class PostfixMathCommand extends FunctionDefinition implements PostfixMathCommandI {
026
027 /**
028 * Number of parameters to be used for the next run() invocation. Applies only if the required umber of parameters is variable
029 * (numberOfParameters = -1).
030 */
031
032 protected int curNumberOfParameters;
033
034 /**
035 * Number of parameters a the function requires. Initialize this value to -1 if any number of parameters should be allowed.
036 */
037
038 protected int numberOfParameters;
039
040 /**
041 * Creates a new PostfixMathCommand class.
042 */
043
044 public PostfixMathCommand (int numParameters) {
045 super ();
046 this.numberOfParameters = numParameters;
047 curNumberOfParameters = numParameters;
048 }
049
050 /**
051 * Return the required number of parameters.
052 */
053
054 public int getNumberOfParameters () {
055 return numberOfParameters;
056 }
057
058 /**
059 * Throws an exception because this method should never be called under normal circumstances. Each function should use it's own run() method
060 * for evaluating the function. This includes popping off the parameters from the stack, and pushing the result back on the stack.
061 */
062
063 public void run (Stack s) throws Exception {
064 throw new Exception ("run() method of PostfixMathCommand called");
065 }
066
067 /**
068 * Sets the number of current number of parameters used in the next call of run(). This method is only called when the reqNumberOfParameters
069 * is -1.
070 */
071
072 public void setCurNumberOfParameters (int n) {
073 curNumberOfParameters = n;
074 }
075
076 /**
077 * Convenience method for use with the parser to set the parameters if they have changed.
078 */
079
080 public void setNumberOfParameters (int n) {
081 numberOfParameters = n;
082 curNumberOfParameters = n;
083 }
084
085 /**
086 * Check whether the stack is not null, throw an Exception if it is.
087 */
088
089 protected void checkStack (Stack inStack) throws Exception {
090
091 /* Check if stack is null */
092 if (null == inStack)
093 throw new Exception ("Stack argument null");
094 }
095 }