- /*
- * 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 1.13 2004/02/17 04:34:00 minchau 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
- {
-
- /**
- * 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 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
- }
- }