- /*
- * The Apache Software License, Version 1.1
- *
- *
- * Copyright (c) 1999 The Apache Software Foundation. All rights
- * reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- *
- * 1. Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer.
- *
- * 2. Redistributions in binary form must reproduce the above copyright
- * notice, this list of conditions and the following disclaimer in
- * the documentation and/or other materials provided with the
- * distribution.
- *
- * 3. The end-user documentation included with the redistribution,
- * if any, must include the following acknowledgment:
- * "This product includes software developed by the
- * Apache Software Foundation (http://www.apache.org/)."
- * Alternately, this acknowledgment may appear in the software itself,
- * if and wherever such third-party acknowledgments normally appear.
- *
- * 4. The names "Xalan" and "Apache Software Foundation" must
- * not be used to endorse or promote products derived from this
- * software without prior written permission. For written
- * permission, please contact apache@apache.org.
- *
- * 5. Products derived from this software may not be called "Apache",
- * nor may "Apache" appear in their name, without prior written
- * permission of the Apache Software Foundation.
- *
- * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
- * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
- * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
- * DISCLAIMED. IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
- * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
- * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
- * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
- * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
- * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
- * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
- * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
- * SUCH DAMAGE.
- * ====================================================================
- *
- * This software consists of voluntary contributions made by many
- * individuals on behalf of the Apache Software Foundation and was
- * originally based on software copyright (c) 1999, Lotus
- * Development Corporation., http://www.lotus.com. For more
- * information on the Apache Software Foundation, please see
- * <http://www.apache.org/>.
- */
- package org.apache.xpath.functions;
-
- //import org.w3c.dom.Node;
-
- import javax.xml.transform.TransformerException;
- 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;
-
- /**
- * <meta name="usage" content="advanced"/>
- * 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.
- */
- 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
- }
- }