http://xmlgraphics.apache.org/fop/: Apache FOP (Formatting Objects Processor) is the world's first print formatter driven by XSL formatting objects (XSL-FO) and the world's first output independent formatter. It is a Java application that reads a formatting object (FO) tree and renders the resulting pages to a specified output. Output formats currently supported include PDF, PCL, PS, AFP, TIFF, PNG, SVG, XML (area tree representation), Print, AWT and TXT. The primary output target is PDF. (Apache Software Foundation) 
/*
 * 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: FunctionBase.java 1547372 2013-12-03 12:44:41Z vhennebert $ */

package org.apache.fop.fo.expr;

import org.apache.fop.datatypes.PercentBase;
import org.apache.fop.fo.properties.Property;
import org.apache.fop.fo.properties.StringProperty;


Abstract Base class for XSL-FO functions

/**
 * Abstract Base class for XSL-FO functions
 */
public abstract class FunctionBase implements Function {

    
{@inheritDoc} 
/** {@inheritDoc} */
    public int getOptionalArgsCount() {
        return 0;
    }

    
{@inheritDoc} 
/** {@inheritDoc} */
    public Property getOptionalArgDefault(int index, PropertyInfo pi) throws PropertyException {
        if (index >= getOptionalArgsCount()) {
            PropertyException e = new PropertyException(
                    new IndexOutOfBoundsException("illegal optional argument index"));
            e.setPropertyInfo(pi);
            throw e;
        } else {
            return null;
        }
    }

    
{@inheritDoc} 
/** {@inheritDoc} */
    public boolean hasVariableArgs() {
        return false;
    }

    
{@inheritDoc} 
/** {@inheritDoc} */
    public PercentBase getPercentBase() {
        return null;
    }

    
Params:
  • pi – property information instance that applies to property being evaluated
Returns:string property whose value is name of property being evaluated
/**
     * @param pi property information instance that applies to property being evaluated
     * @return string property whose value is name of property being evaluated
     */
    protected final Property getPropertyName(PropertyInfo pi) {
        return StringProperty.getInstance(pi.getPropertyMaker().getName());
    }
}