documentnavigator.java

XML的解析、编译、查询等技术的JAVA源代码。

package org.jaxen.dom;

/*
 * $Header: /home/projects/jaxen/scm/jaxen/src/java/main/org/jaxen/dom/DocumentNavigator.java,v 1.56 2006/07/03 13:08:43 elharo Exp $
 * $Revision: 1.56 $
 * $Date: 2006/07/03 13:08:43 $
 *
 * ====================================================================
 *
 * Copyright 2000-2005 bob mcwhirter & James Strachan.
 * All rights reserved.
 *
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met:
 * 
 *   * Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 * 
 *   * 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.
 * 
 *   * Neither the name of the Jaxen Project nor the names of its
 *     contributors may be used to endorse or promote products derived 
 *     from this software without specific prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
 * IS" AND ANY EXPRESS 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 COPYRIGHT OWNER
 * OR 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 Jaxen Project and was originally
 * created by bob mcwhirter <[e-mail]> and
 * James Strachan <[e-mail]>.  For more information on the
 * Jaxen Project, please see <http://www.jaxen.org/>.
 *
 * $Id: DocumentNavigator.java,v 1.56 2006/07/03 13:08:43 elharo Exp $
*/

import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;

import java.io.IOException;
import java.util.HashMap;
import java.util.Iterator;
import java.util.NoSuchElementException;

import org.jaxen.DefaultNavigator;
import org.jaxen.FunctionCallException;
import org.jaxen.Navigator;
import org.jaxen.XPath;
import org.jaxen.JaxenConstants;
import org.w3c.dom.Attr;
import org.w3c.dom.Document;
import org.w3c.dom.NamedNodeMap;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
import org.w3c.dom.ProcessingInstruction;
import org.xml.sax.SAXException;

/** Interface for navigating around the W3C DOM Level 2 object model.
 *
 *  <p>
 *  This class is not intended for direct usage, but is
 *  used by the Jaxen engine during evaluation.
 *  </p>
 *
 *  <p>This class implements the {@link org.jaxen.DefaultNavigator} interface
 *  for the Jaxen XPath library.  This adapter allows the Jaxen
 *  library to be used to execute XPath queries against any object tree
 *  that implements the DOM level 2 interfaces.</p>
 *
 *  <p>Note: DOM level 2 does not include a node representing an XPath
 *  namespace node.  This navigator will return namespace nodes
 *  as instances of the custom {@link NamespaceNode} class, and
 *  users will have to check result sets to locate and isolate
 *  these.</p>
 *
 *  @author David Megginson
 *  @author James Strachan
 *
 *  @see XPath
 *  @see NamespaceNode
 */
public class DocumentNavigator extends DefaultNavigator
{

    
    ////////////////////////////////////////////////////////////////////
    // Constants.
    ////////////////////////////////////////////////////////////////////

    /**
     * 
     */
    private static final long serialVersionUID = 8460943068889528115L; 
    
    private final static DocumentNavigator SINGLETON = new DocumentNavigator();


    
    ////////////////////////////////////////////////////////////////////
    // Constructor.
    ////////////////////////////////////////////////////////////////////


    /**
     * Default constructor.
     */
    public DocumentNavigator ()
    {
    }


    /**
     * Get a constant DocumentNavigator for efficiency.
     *
     * @return a constant instance of a DocumentNavigator.
     */
    public static Navigator getInstance ()
    {
        return SINGLETON;
    }


    
    ////////////////////////////////////////////////////////////////////
    // Implementation of org.jaxen.DefaultNavigator.
    ////////////////////////////////////////////////////////////////////


    /**
     * Get an iterator over all of this node's children.
     *
     * @param contextNode the context node for the child axis.
     * @return a possibly-empty iterator (not null)
     */
    public Iterator getChildAxisIterator (Object contextNode)
    {
        return new NodeIterator ((Node)contextNode) {
                protected Node getFirstNode (Node node)
                {
                    return node.getFirstChild();
                }
                protected Node getNextNode (Node node)
                {
                    return node.getNextSibling();
                }
            };
    }


    /**
     * Get a (single-member) iterator over this node's parent.
     *
     * @param contextNode the context node for the parent axis
     * @return a possibly-empty iterator (not null)
     */
    public Iterator getParentAxisIterator (Object contextNode)
    {
        Node node = (Node)contextNode;

        if (node.getNodeType() == Node.ATTRIBUTE_NODE) {
            return new NodeIterator (node) {
                    protected Node getFirstNode (Node n)
                    {
                        // We can assume castability here because we've already
                        // tested the node type.
                        return ((Attr)n).getOwnerElement();
                    }
                    protected Node getNextNode (Node n) {
                        return null;
                    }
                };
        } else {
            return new NodeIterator (node) {
                    protected Node getFirstNode (Node n)
                    {
                        return n.getParentNode();
                    }
                    protected Node getNextNode (Node n) {
                        return null;
                    }
                };
        }
    }
    
    
    /** 
     * Return the XPath parent of this DOM node.
     * XPath has slightly different definition of parent than DOM does.
     * In particular, the parent of an attribute is not null.
     * 
     * @param o 
     * 
     * @return the parent of the specified node; or null if
     *     the node does not have a parent
     */
    public Object getParentNode(Object o) {
        Node node = (Node) o;
        if (node.getNodeType() == Node.ATTRIBUTE_NODE) {
            return ((Attr) node).getOwnerElement();
        }
        return node.getParentNode();
    }


    /**
     * Get an iterator over all following siblings.
     *
     * @param contextNode the context node for the sibling iterator
     * @return a possibly-empty iterator (not null)
     */
    public Iterator getFollowingSiblingAxisIterator (Object contextNode)
    {
        return new NodeIterator ((Node)contextNode) {
                protected Node getFirstNode (Node node)
                {
                    return getNextNode(node);
                }
                protected Node getNextNode (Node node) {
                    return node.getNextSibling();
                }
            };
    }


    /**
     * Get an iterator over all preceding siblings.
     *
     * @param contextNode the context node for the preceding sibling axis
     * @return a possibly-empty iterator (not null)
     */
    public Iterator getPrecedingSiblingAxisIterator (Object contextNode)
    {
        return new NodeIterator ((Node)contextNode) {
                protected Node getFirstNode (Node node)
                {
                    return getNextNode(node);
                }
                protected Node getNextNode (Node node) {
                    return node.getPreviousSibling();
                }
            };
    }


    /**
     * Get an iterator over all following nodes, depth-first.
     *
     * @param contextNode the context node for the following axis
     * @return a possibly-empty iterator (not null)
     */
    public Iterator getFollowingAxisIterator (Object contextNode)
    {
        return new NodeIterator ((Node)contextNode) {
                protected Node getFirstNode (Node node)
                {
                    if (node == null) {
                        return null;
                    }
                    else {
                        Node sibling = node.getNextSibling();
                        if (sibling == null) {
                            return getFirstNode(node.getParentNode());
                        }
                        else {
                            return sibling;
                        }
                    }
                }
                protected Node getNextNode (Node node) {
                    if (node == null) {
                        return null;
                    }
                    else {
                        Node n = node.getFirstChild();
                        if (n == null) n = node.getNextSibling();
                        if (n == null) return getFirstNode(node.getParentNode());
                        else return n;
                    }
                }
            };
    }


    /**
     * Get an iterator over all attributes.
     *
     * @param contextNode the context node for the attribute axis
     * @return a possibly-empty iterator (not null)
     */
    public Iterator getAttributeAxisIterator (Object contextNode)
    {
        if (isElement(contextNode)) {
            return new AttributeIterator((Node)contextNode);
        } 
        else {
            return JaxenConstants.EMPTY_ITERATOR;
        }
    }


    /**
     * Get an iterator over all declared namespaces.
     *
     * <p>Note: this iterator is not live: it takes a snapshot
     * and that snapshot remains static during the life of
     * the iterator (i.e. it won't reflect subsequent changes
     * to the DOM).</p>
     * 
     * <p>
     * In the event that the DOM is inconsistent; for instance a 
     * <code>pre:foo</code> element is declared by DOM to be in the 
     * http://www.a.com/ namespace but also has an 
     * <code>xmlns:pre="http://www.b.com"</code> attribute; then only 
     * one of the namespaces will be counted. This will be the intrinsic
     * namespace of the <code>Element</code> or <code>Attr</code> object
     * rather than the one provide by the contradictory namespace 
     * declaration attribute. In the event of a contradiction between two
     * attributes on the same element--e.g. <code>pre:foo</code> in the
     * http://www.a.com/ namespace and <code>pre:bar</code> in the 
     * http://www.b.com/ namespace--it is undefined which namespace
     * will be returned. 
     * </p>
     *
     * @param contextNode the context node for the namespace axis
     * @return a possibly-empty iterator (not null)
     */
    public Iterator getNamespaceAxisIterator (Object contextNode)
    {
        // Only elements have namespace nodes
        if (isElement(contextNode)) {

            HashMap nsMap = new HashMap();

            // Starting at the current node, walk
            // up to the root, noting the namespace
            // declarations in scope.
            for (Node n = (Node) contextNode;
                 n != null;
                 n = n.getParentNode()) {