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 * Copyright (c) 2015, 2017, Oracle and/or its affiliates. All rights reserved.
 */
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/**
 * 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.
 */
package com.sun.org.apache.xpath.internal.functions;

import com.sun.org.apache.xml.internal.dtm.DTM;
import com.sun.org.apache.xml.internal.utils.QName;
import com.sun.org.apache.xpath.internal.NodeSetDTM;
import com.sun.org.apache.xpath.internal.XPathContext;
import com.sun.org.apache.xpath.internal.objects.XNodeSet;
import com.sun.org.apache.xpath.internal.objects.XObject;
import com.sun.org.apache.xpath.internal.res.XPATHErrorResources;
import java.util.List;
import javax.xml.transform.TransformerException;
import org.w3c.dom.Document;
import org.w3c.dom.Node;

Execute the XML Signature here() function.
@LastModified
: Oct 2017/**
 * Execute the XML Signature here() function.
 *
 * @LastModified: Oct 2017
 */
public final class FuncHere extends Function {

    private static final long serialVersionUID = 4328660760070034592L;

    @Override
    public XObject execute(XPathContext xctxt) throws TransformerException {
        Node xpathOwnerNode = (Node)xctxt.getOwnerObject();
        if (xpathOwnerNode == null) {
            return null;
        }

        int xpathOwnerNodeDTM = xctxt.getDTMHandleFromNode(xpathOwnerNode);
        int currentNode = xctxt.getCurrentNode();
        DTM dtm = xctxt.getDTM(currentNode);
        int docContext = dtm.getDocument();

        if (docContext == DTM.NULL) {
            error(xctxt, XPATHErrorResources.ER_CONTEXT_HAS_NO_OWNERDOC, null);
        }

        // check whether currentNode and the node containing the XPath
        // expression are in the same document
        Document currentDoc = getOwnerDocument(dtm.getNode(currentNode));
        Document xpathOwnerDoc = getOwnerDocument(xpathOwnerNode);

        if (currentDoc != xpathOwnerDoc) {
            throw new TransformerException("Owner documents differ");
        }

        XNodeSet nodes = new XNodeSet(xctxt.getDTMManager());
        NodeSetDTM nodeSet = nodes.mutableNodeset();

        int hereNode = DTM.NULL;

        switch (dtm.getNodeType(xpathOwnerNodeDTM)) {

            case Node.ATTRIBUTE_NODE:
            case Node.PROCESSING_INSTRUCTION_NODE: {
                // returns a node-set containing the attribute /  processing
                // instruction node
                hereNode = xpathOwnerNodeDTM;
                nodeSet.addNode(hereNode);
                break;
            }
            case Node.TEXT_NODE : {
                // returns a node-set containing the parent element of the
                // text node that directly bears the XPath expression
                hereNode = dtm.getParent(xpathOwnerNodeDTM);
                nodeSet.addNode(hereNode);
                break;
            }
            default :
                break;
        }

        /** $todo$ Do I have to do this detach() call? */
        nodeSet.detach();

        return nodes;
    }

    private static Document getOwnerDocument(Node node) {
        if (node.getNodeType() == Node.DOCUMENT_NODE) {
            return (Document)node;
        }
        return node.getOwnerDocument();
    }

    @Override
    public void fixupVariables(List<QName> vars, int globalsSize) { }
}