de.betterform.xml.xforms.xpath.saxon.function.Changed.java Source code

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Here is the source code for de.betterform.xml.xforms.xpath.saxon.function.Changed.java

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/*
 * Copyright (c) 2012. betterFORM Project - http://www.betterform.de
 * Licensed under the terms of BSD License
 */

package de.betterform.xml.xforms.xpath.saxon.function;

import de.betterform.xml.dom.DOMUtil;
import de.betterform.xml.xforms.exception.XFormsException;
import de.betterform.xml.xpath.impl.saxon.XPathUtil;
import net.sf.saxon.dom.NodeWrapper;
import net.sf.saxon.expr.XPathContext;
import net.sf.saxon.om.Item;
import net.sf.saxon.trans.XPathException;
import net.sf.saxon.value.BooleanValue;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.w3c.dom.Document;
import org.w3c.dom.Node;

public class Changed extends XFormsFunction {
    private static final long serialVersionUID = -8152654592543207734L;
    private static Log LOGGER = LogFactory.getLog(Changed.class);

    /**
     * Evaluate in a general context
     */
    public Item evaluateItem(XPathContext xpathContext) throws XPathException {

        Item item = argument[0].evaluateItem(xpathContext);
        if (item != null) {
            Node node = (Node) ((NodeWrapper) item).getUnderlyingNode();
            String xpath = DOMUtil.getCanonicalPath(node);
            //            String currentValue = (String) argument[0].evaluateAsString(xpathContext);
            String currentValue = DOMUtil.getTextNodeAsString(node);

            de.betterform.xml.xforms.model.Instance owner = (de.betterform.xml.xforms.model.Instance) node
                    .getOwnerDocument().getDocumentElement().getUserData("instance");
            String initialValue = null;
            try {
                Document initial = owner.getInitialInstance();
                if (LOGGER.isDebugEnabled()) {
                    LOGGER.debug("Initial Instance: START:");
                    DOMUtil.prettyPrintDOM(initial);
                    LOGGER.debug("\nInitial Instance: STOP");
                }

                initialValue = XPathUtil.evaluateAsString(initial, xpath);
            } catch (XFormsException e) {
                throw new XPathException("initial Instance couldn't be fetched", e);
            }

            if (currentValue.equals(initialValue)) {
                return BooleanValue.FALSE;
            } else {
                return BooleanValue.TRUE;
            }
        } else {
            LOGGER.warn("Item for " + xpathContext.toString() + " couldn't be found");
            return BooleanValue.FALSE;
        }

    }

}