alvinalexander.com | career | drupal | java | mac | mysql | perl | scala | uml | unix  

Java example source code file (TreeWalkerImpl.java)

This example Java source code file (TreeWalkerImpl.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

dom, node, nodefilter, not_supported_err, string, treewalkerimpl

The TreeWalkerImpl.java Java example source code

/*
 * reserved comment block
 * DO NOT REMOVE OR ALTER!
 */
/*
 * Copyright 1999-2002,2004 The Apache Software Foundation.
 *
 * Licensed 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.xerces.internal.dom;

import org.w3c.dom.DOMException;
import org.w3c.dom.Node;
import org.w3c.dom.traversal.NodeFilter;
import org.w3c.dom.traversal.TreeWalker;

/** This class implements the TreeWalker interface.
 *
 * @xerces.internal
 *
 */

public class TreeWalkerImpl implements TreeWalker {

    //
    // Data
    //

    /** When TRUE, the children of entites references are returned in the iterator. */
    private boolean fEntityReferenceExpansion = false;
    /** The whatToShow mask. */
    int fWhatToShow = NodeFilter.SHOW_ALL;
    /** The NodeFilter reference. */
    NodeFilter fNodeFilter;
    /** The current Node. */
    Node fCurrentNode;
    /** The root Node. */
    Node fRoot;

    //
    // Implementation Note: No state is kept except the data above
    // (fWhatToShow, fNodeFilter, fCurrentNode, fRoot) such that
    // setters could be created for these data values and the
    // implementation will still work.


    //
    // Constructor
    //

    /** Public constructor */
    public TreeWalkerImpl(Node root,
                          int whatToShow,
                          NodeFilter nodeFilter,
                          boolean entityReferenceExpansion) {
        fCurrentNode = root;
        fRoot = root;
        fWhatToShow = whatToShow;
        fNodeFilter = nodeFilter;
        fEntityReferenceExpansion = entityReferenceExpansion;
    }

    public Node getRoot() {
        return fRoot;
    }

    /** Return the whatToShow value */
    public int                getWhatToShow() {
        return fWhatToShow;
    }

    public void setWhatShow(int whatToShow){
        fWhatToShow = whatToShow;
    }
    /** Return the NodeFilter */
    public NodeFilter         getFilter() {
        return fNodeFilter;
    }

    /** Return whether children entity references are included in the iterator. */
    public boolean            getExpandEntityReferences() {
        return fEntityReferenceExpansion;
    }

    /** Return the current Node. */
    public Node               getCurrentNode() {
        return fCurrentNode;
    }
    /** Return the current Node. */
    public void               setCurrentNode(Node node) {
        if (node == null) {
            String msg = DOMMessageFormatter.formatMessage(DOMMessageFormatter.DOM_DOMAIN, "NOT_SUPPORTED_ERR", null);
              throw new DOMException(DOMException.NOT_SUPPORTED_ERR, msg);
        }

        fCurrentNode = node;
    }

    /** Return the parent Node from the current node,
     *  after applying filter, whatToshow.
     *  If result is not null, set the current Node.
     */
    public Node               parentNode() {

        if (fCurrentNode == null) return null;

        Node node = getParentNode(fCurrentNode);
        if (node !=null) {
            fCurrentNode = node;
        }
        return node;

    }

    /** Return the first child Node from the current node,
     *  after applying filter, whatToshow.
     *  If result is not null, set the current Node.
     */
    public Node               firstChild() {

        if (fCurrentNode == null) return null;

        Node node = getFirstChild(fCurrentNode);
        if (node !=null) {
            fCurrentNode = node;
        }
        return node;
    }
    /** Return the last child Node from the current node,
     *  after applying filter, whatToshow.
     *  If result is not null, set the current Node.
     */
    public Node               lastChild() {

        if (fCurrentNode == null) return null;

        Node node = getLastChild(fCurrentNode);
        if (node !=null) {
            fCurrentNode = node;
        }
        return node;
    }

    /** Return the previous sibling Node from the current node,
     *  after applying filter, whatToshow.
     *  If result is not null, set the current Node.
     */
    public Node               previousSibling() {

        if (fCurrentNode == null) return null;

        Node node = getPreviousSibling(fCurrentNode);
        if (node !=null) {
            fCurrentNode = node;
        }
        return node;
    }

    /** Return the next sibling Node from the current node,
     *  after applying filter, whatToshow.
     *  If result is not null, set the current Node.
     */
    public Node               nextSibling(){
        if (fCurrentNode == null) return null;

        Node node = getNextSibling(fCurrentNode);
        if (node !=null) {
            fCurrentNode = node;
        }
        return node;
    }

    /** Return the previous Node from the current node,
     *  after applying filter, whatToshow.
     *  If result is not null, set the current Node.
     */
    public Node               previousNode() {
        Node result;

        if (fCurrentNode == null) return null;

        // get sibling
        result = getPreviousSibling(fCurrentNode);
        if (result == null) {
            result = getParentNode(fCurrentNode);
            if (result != null) {
                fCurrentNode = result;
                return fCurrentNode;
            }
            return null;
        }

        // get the lastChild of result.
        Node lastChild  = getLastChild(result);

        Node prev = lastChild ;
        while (lastChild != null) {
          prev = lastChild ;
          lastChild = getLastChild(prev) ;
        }

        lastChild = prev ;

        // if there is a lastChild which passes filters return it.
        if (lastChild != null) {
            fCurrentNode = lastChild;
            return fCurrentNode;
        }

        // otherwise return the previous sibling.
        if (result != null) {
            fCurrentNode = result;
            return fCurrentNode;
        }

        // otherwise return null.
        return null;
    }

    /** Return the next Node from the current node,
     *  after applying filter, whatToshow.
     *  If result is not null, set the current Node.
     */
    public Node               nextNode() {

        if (fCurrentNode == null) return null;

        Node result = getFirstChild(fCurrentNode);

        if (result != null) {
            fCurrentNode = result;
            return result;
        }

        result = getNextSibling(fCurrentNode);

        if (result != null) {
            fCurrentNode = result;
            return result;
        }

        // return parent's 1st sibling.
        Node parent = getParentNode(fCurrentNode);
        while (parent != null) {
            result = getNextSibling(parent);
            if (result != null) {
                fCurrentNode = result;
                return result;
            } else {
                parent = getParentNode(parent);
            }
        }

        // end , return null
        return null;
    }

    /** Internal function.
     *  Return the parent Node, from the input node
     *  after applying filter, whatToshow.
     *  The current node is not consulted or set.
     */
    Node getParentNode(Node node) {

        if (node == null || node == fRoot) return null;

        Node newNode = node.getParentNode();
        if (newNode == null)  return null;

        int accept = acceptNode(newNode);

        if (accept == NodeFilter.FILTER_ACCEPT)
            return newNode;
        else
        //if (accept == NodeFilter.SKIP_NODE) // and REJECT too.
        {
            return getParentNode(newNode);
        }


    }

    /** Internal function.
     *  Return the nextSibling Node, from the input node
     *  after applying filter, whatToshow.
     *  The current node is not consulted or set.
     */
    Node getNextSibling(Node node) {
                return getNextSibling(node, fRoot);
        }

    /** Internal function.
     *  Return the nextSibling Node, from the input node
     *  after applying filter, whatToshow.
     *  NEVER TRAVERSES ABOVE THE SPECIFIED ROOT NODE.
     *  The current node is not consulted or set.
     */
    Node getNextSibling(Node node, Node root) {

        if (node == null || node == root) return null;

        Node newNode = node.getNextSibling();
        if (newNode == null) {

            newNode = node.getParentNode();

            if (newNode == null || newNode == root)  return null;

            int parentAccept = acceptNode(newNode);

            if (parentAccept==NodeFilter.FILTER_SKIP) {
                return getNextSibling(newNode, root);
            }

            return null;
        }

        int accept = acceptNode(newNode);

        if (accept == NodeFilter.FILTER_ACCEPT)
            return newNode;
        else
        if (accept == NodeFilter.FILTER_SKIP) {
            Node fChild = getFirstChild(newNode);
            if (fChild == null) {
                return getNextSibling(newNode, root);
            }
            return fChild;
        }
        else
        //if (accept == NodeFilter.REJECT_NODE)
        {
            return getNextSibling(newNode, root);
        }

    } // getNextSibling(Node node) {

    /** Internal function.
     *  Return the previous sibling Node, from the input node
     *  after applying filter, whatToshow.
     *  The current node is not consulted or set.
     */
    Node getPreviousSibling(Node node) {
                return getPreviousSibling(node, fRoot);
        }

    /** Internal function.
     *  Return the previousSibling Node, from the input node
     *  after applying filter, whatToshow.
         *  NEVER TRAVERSES ABOVE THE SPECIFIED ROOT NODE.
     *  The current node is not consulted or set.
     */
    Node getPreviousSibling(Node node, Node root) {

        if (node == null || node == root) return null;

        Node newNode = node.getPreviousSibling();
        if (newNode == null) {

            newNode = node.getParentNode();
            if (newNode == null || newNode == root)  return null;

            int parentAccept = acceptNode(newNode);

            if (parentAccept==NodeFilter.FILTER_SKIP) {
                return getPreviousSibling(newNode, root);
            }

            return null;
        }

        int accept = acceptNode(newNode);

        if (accept == NodeFilter.FILTER_ACCEPT)
            return newNode;
        else
        if (accept == NodeFilter.FILTER_SKIP) {
            Node fChild =  getLastChild(newNode);
            if (fChild == null) {
                return getPreviousSibling(newNode, root);
            }
            return fChild;
        }
        else
        //if (accept == NodeFilter.REJECT_NODE)
        {
            return getPreviousSibling(newNode, root);
        }

    } // getPreviousSibling(Node node) {

    /** Internal function.
     *  Return the first child Node, from the input node
     *  after applying filter, whatToshow.
     *  The current node is not consulted or set.
     */
    Node getFirstChild(Node node) {
        if (node == null) return null;

        if ( !fEntityReferenceExpansion
             && node.getNodeType() == Node.ENTITY_REFERENCE_NODE)
            return null;
        Node newNode = node.getFirstChild();
        if (newNode == null)  return null;
        int accept = acceptNode(newNode);

        if (accept == NodeFilter.FILTER_ACCEPT)
            return newNode;
        else
        if (accept == NodeFilter.FILTER_SKIP
            && newNode.hasChildNodes())
        {
            Node fChild = getFirstChild(newNode);

            if (fChild == null) {
                return getNextSibling(newNode, node);
            }
            return fChild;
        }
        else
        //if (accept == NodeFilter.REJECT_NODE)
        {
            return getNextSibling(newNode, node);
        }


    }

    /** Internal function.
     *  Return the last child Node, from the input node
     *  after applying filter, whatToshow.
     *  The current node is not consulted or set.
     */
    Node getLastChild(Node node) {

        if (node == null) return null;

        if ( !fEntityReferenceExpansion
             && node.getNodeType() == Node.ENTITY_REFERENCE_NODE)
            return null;

        Node newNode = node.getLastChild();
        if (newNode == null)  return null;

        int accept = acceptNode(newNode);

        if (accept == NodeFilter.FILTER_ACCEPT)
            return newNode;
        else
        if (accept == NodeFilter.FILTER_SKIP
            && newNode.hasChildNodes())
        {
            Node lChild = getLastChild(newNode);
            if (lChild == null) {
                return getPreviousSibling(newNode, node);
            }
            return lChild;
        }
        else
        //if (accept == NodeFilter.REJECT_NODE)
        {
            return getPreviousSibling(newNode, node);
        }


    }

    /** Internal function.
     *  The node whatToShow and the filter are combined into one result. */
    short acceptNode(Node node) {
        /***
         7.1.2.4. Filters and whatToShow flags

         Iterator and TreeWalker apply whatToShow flags before applying Filters. If a node is rejected by the
         active whatToShow flags, a Filter will not be called to evaluate that node. When a node is rejected by
         the active whatToShow flags, children of that node will still be considered, and Filters may be called to
         evaluate them.
         ***/

        if (fNodeFilter == null) {
            if ( ( fWhatToShow & (1 << node.getNodeType()-1)) != 0) {
                return NodeFilter.FILTER_ACCEPT;
            } else {
                return NodeFilter.FILTER_SKIP;
            }
        } else {
            if ((fWhatToShow & (1 << node.getNodeType()-1)) != 0 ) {
                return fNodeFilter.acceptNode(node);
            } else {
                // What to show has failed. See above excerpt from spec.
                // Equivalent to FILTER_SKIP.
                return NodeFilter.FILTER_SKIP;
            }
        }
    }
}

Other Java examples (source code examples)

Here is a short list of links related to this Java TreeWalkerImpl.java source code file:

... this post is sponsored by my books ...

#1 New Release!

FP Best Seller

 

new blog posts

 

Copyright 1998-2021 Alvin Alexander, alvinalexander.com
All Rights Reserved.

A percentage of advertising revenue from
pages under the /java/jwarehouse URI on this website is
paid back to open source projects.