fop/src/java/org/apache/fop/fo/expr/BodyStartFunction.java

/*
 * $Id: BodyStartFunction.java,v 1.4 2003/03/05 21:59:47 jeremias Exp $
 * ============================================================================
 *                    The Apache Software License, Version 1.1
 * ============================================================================
 *
 * Copyright (C) 1999-2003 The Apache Software Foundation. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without modifica-
 * tion, 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 "FOP" 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.
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 * 5. Products derived from this software may not be called "Apache", nor may
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 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED WARRANTIES,
 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
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 * APACHE SOFTWARE FOUNDATION OR ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
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 * 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 created by
 * James Tauber <jtauber@jtauber.com>. For more information on the Apache
 * Software Foundation, please see <http://www.apache.org/>.
 */
package org.apache.fop.fo.expr;

import org.apache.fop.datatypes.Numeric;
import org.apache.fop.fo.Constants;
import org.apache.fop.fo.FONode;
import org.apache.fop.fo.flow.ListItem;
import org.apache.fop.fo.properties.Property;

/**
 * Class corresponding to the body-start Property Value function. See Sec.
 * 5.10.4 of the XSL-FO spec.
 */
public class BodyStartFunction extends FunctionBase {

    /**
     * @return 0 (there are no arguments for body-start)
     */
    public int nbArgs() {
        return 0;
    }

    /**
     * @param args array of arguments (none are used, but this is required by
     * the Function interface)
     * @param pInfo PropertyInfo object to be evaluated
     * @return numeric object containing the calculated body-start value
     * @throws PropertyException if called from outside of an fo:list-item
     */
    public Property eval(Property[] args,
                         PropertyInfo pInfo) throws PropertyException {
        Numeric distance =
            pInfo.getPropertyList().get(Constants.PR_PROVISIONAL_DISTANCE_BETWEEN_STARTS).getNumeric();

        FONode item = pInfo.getFO();
        while (item != null && !(item instanceof ListItem)) {
            item = item.getParent();
        }
        if (item == null) {
            throw new PropertyException("body-start() called from outside an fo:list-item");
        }

        Numeric startIndent =
            ((ListItem)item).propertyList.get(Constants.PR_START_INDENT).getNumeric();

        return (Property) NumericOp.addition(distance, startIndent);
    }

}