/* * reserved comment block * DO NOT REMOVE OR ALTER! */ /* * Copyright 1999-2004 The 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. */ /* * $Id: Function.java,v 1.2.4.1 2005/09/14 20:18:43 jeffsuttor Exp $ */ package com.sun.org.apache.xpath.internal.functions; import com.sun.org.apache.xalan.internal.res.XSLMessages; import com.sun.org.apache.xpath.internal.Expression; import com.sun.org.apache.xpath.internal.ExpressionOwner; import com.sun.org.apache.xpath.internal.XPathContext; import com.sun.org.apache.xpath.internal.XPathVisitor; import com.sun.org.apache.xpath.internal.compiler.Compiler; import com.sun.org.apache.xpath.internal.objects.XObject; /** * This is a superclass of all XPath functions. This allows two * ways for the class to be called. One method is that the * super class processes the arguments and hands the results to * the derived class, the other method is that the derived * class may process it's own arguments, which is faster since * the arguments don't have to be added to an array, but causes * a larger code footprint. * @xsl.usage advanced */ public abstract class Function extends Expression { static final long serialVersionUID = 6927661240854599768L; /** * Set an argument expression for a function. This method is called by the * XPath compiler. * * @param arg non-null expression that represents the argument. * @param argNum The argument number index. * * @throws WrongNumberArgsException If the argNum parameter is beyond what * is specified for this function. */ public void setArg(Expression arg, int argNum) throws WrongNumberArgsException { // throw new WrongNumberArgsException(XSLMessages.createXPATHMessage("zero", null)); reportWrongNumberArgs(); } /** * Check that the number of arguments passed to this function is correct. * This method is meant to be overloaded by derived classes, to check for * the number of arguments for a specific function type. This method is * called by the compiler for static number of arguments checking. * * @param argNum The number of arguments that is being passed to the function. * * @throws WrongNumberArgsException */ public void checkNumberArgs(int argNum) throws WrongNumberArgsException { if (argNum != 0) reportWrongNumberArgs(); } /** * Constructs and throws a WrongNumberArgException with the appropriate * message for this function object. This method is meant to be overloaded * by derived classes so that the message will be as specific as possible. * * @throws WrongNumberArgsException */ protected void reportWrongNumberArgs() throws WrongNumberArgsException { throw new WrongNumberArgsException(XSLMessages.createXPATHMessage("zero", null)); } /** * Execute an XPath function object. The function must return * a valid object. * @param xctxt The execution current context. * @return A valid XObject. * * @throws javax.xml.transform.TransformerException */ public XObject execute(XPathContext xctxt) throws javax.xml.transform.TransformerException { // Programmer's assert. (And, no, I don't want the method to be abstract). System.out.println("Error! Function.execute should not be called!"); return null; } /** * Call the visitors for the function arguments. */ public void callArgVisitors(XPathVisitor visitor) { } /** * @see com.sun.org.apache.xpath.internal.XPathVisitable#callVisitors(ExpressionOwner, XPathVisitor) */ public void callVisitors(ExpressionOwner owner, XPathVisitor visitor) { if(visitor.visitFunction(owner, this)) { callArgVisitors(visitor); } } /** * @see Expression#deepEquals(Expression) */ public boolean deepEquals(Expression expr) { if(!isSameClass(expr)) return false; return true; } /** * This function is currently only being used by Position() * and Last(). See respective functions for more detail. */ public void postCompileStep(Compiler compiler) { // no default action } }