| /* |
| * Licensed to the Apache Software Foundation (ASF) under one |
| * or more contributor license agreements. See the NOTICE file |
| * distributed with this work for additional information |
| * regarding copyright ownership. The ASF licenses this file |
| * to you 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 468655 2006-10-28 07:12:06Z minchau $ |
| */ |
| package org.apache.xpath.functions; |
| |
| import org.apache.xalan.res.XSLMessages; |
| import org.apache.xpath.Expression; |
| import org.apache.xpath.ExpressionOwner; |
| import org.apache.xpath.XPathContext; |
| import org.apache.xpath.XPathVisitor; |
| import org.apache.xpath.compiler.Compiler; |
| import org.apache.xpath.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 org.apache.xpath.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 |
| } |
| } |