nodefilterlocator.java

用Java写的面相对象的数据库管理系统

// Copyright 1997-1999 by softwarebuero m&b (SMB). All rights reserved.
//
// You can redistribute this software and/or modify it under the terms of
// the Ozone Library License version 1 published by softwarebuero m&b (SMB).
//
// $Id: NodeFilterLocator.java,v 1.3 2000/10/28 16:55:25 daniela Exp $

package org.ozoneDB.xml.xpath;

import java.util.Stack;
import java.util.Vector;

import org.w3c.dom.Document;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
import org.w3c.dom.traversal.DocumentTraversal;
import org.w3c.dom.traversal.NodeFilter;
import org.w3c.dom.traversal.TreeWalker;

import org.apache.xalan.xpath.*;
import org.apache.xalan.xpath.xml.*;

/**
 * 
 * This class only compiles if you have a working Xalan 1.0.1 in your classpath!
 * 
 * 
 * @version $Revision: 1.3 $ $Date: 2000/10/28 16:55:25 $
 * @author <a href="http://www.softwarebuero.de">SMB</a>
 */
public class NodeFilterLocator extends SimpleNodeLocator {
    
    protected TreeWalker walker = null;
    protected Stack walkerStack;
    
    protected NodeFilter filter;
    protected DocumentTraversal traversal;
    
    /** The singleton instance of this class.*/
    private static NodeFilterLocator m_locater = null;
    
    
    public NodeFilterLocator( DocumentTraversal traversal, NodeFilter filter ) {
        this.traversal = traversal;
        this.filter = filter;
        this.walkerStack = new Stack();
    }
    
    
    public NodeFilterLocator() {
    }
    
    
    public static XLocator getDefaultLocator() {
        m_locater = null == m_locater ? new NodeFilterLocator() : m_locater;
        return m_locater;
    } 
    
    
    /** need overwrite this method, to build a treewalker stack */
    protected MutableNodeList step( XPath xpath, XPathSupport execContext, Node context, int opPos,
            NodeCallback callback, Object callbackInfo, boolean isSimpleFollowing, boolean stopAtFirst ) 
            throws org.xml.sax.SAXException {
        
        // cerate a new walker with current context node
        walker = traversal.createTreeWalker( context, NodeFilter.SHOW_ALL, filter, true );
        walkerStack.push( walker );
        
        MutableNodeList result = 
                super.step( xpath, execContext, context, opPos, callback, callbackInfo, isSimpleFollowing,
                stopAtFirst );
        
        walker = (TreeWalker)walkerStack.pop();
        
        return result;
    } 
    
    
    /** need to overwrite this method, to call traversal methods */
    protected MutableNodeList findChildren( XPath xpath, XPathSupport execContext, Node context, int opPos,
            int stepType, MutableNodeList subQueryResults, NodeCallback callback, Object callbackInfo,
            boolean isSimpleFollowing, boolean stopAtFirst ) throws org.xml.sax.SAXException {
        
        int argLen = xpath.getArgLengthOfStep( opPos );
        opPos = xpath.getFirstChildPosOfStep( opPos );
        
        // If using a document fragment with references (non-standard)
        // we can not use the next-sibling business at the top level.
        if (Node.DOCUMENT_FRAGMENT_NODE != context.getNodeType()) {
            
            // DOM2-Traversal
            Node c = walker.firstChild();
            
            while (null != c) {
                if (XPath.MATCH_SCORE_NONE != nodeTest( xpath, execContext, c, opPos, argLen, stepType )) {
                    // or else call execute method.  If no execute method,
                    // add the node.
                    // subQueryResults.addNode(c);
                    if (isSimpleFollowing && null != callback) {
                        execContext.incrementContextNodePosition( c );
                        if (predicate( xpath, execContext, c, opPos + argLen )) {
                            callback.processLocatedNode( execContext, c, callbackInfo );
                            if (stopAtFirst) {
                                break;
                            } 
                        } 
                    } else {
                        subQueryResults = addNode( subQueryResults, c );
                    } 
                } 
                // DOM2-Traversal
                c = walker.nextSibling();
            } 
        } else {
            // DOM2-Traversal
            Node c = walker.firstChild();
            while (null != c) {
                if (XPath.MATCH_SCORE_NONE != nodeTest( xpath, execContext, c, opPos, argLen, stepType )) {
                    // subQueryResults.addNode(c);
                    if (isSimpleFollowing && null != callback) {
                        execContext.incrementContextNodePosition( c );
                        if (predicate( xpath, execContext, c, opPos + argLen )) {
                            callback.processLocatedNode( execContext, c, callbackInfo );
                            if (stopAtFirst) {
                                break;
                            } 
                        } 
                    } else {
                        subQueryResults = addNode( subQueryResults, c );
                    } 
                } 
                // DOM2-Traversal
                c = walker.nextSibling();
            } 
        } 
        return subQueryResults;
    } 
    
    
    /** need overwrite this method, to call traversal methods */
    protected MutableNodeList findDescendants( XPath xpath, XPathSupport execContext, Node context, int opPos,
            int stepType, MutableNodeList subQueryResults, NodeCallback callback, Object callbackInfo,
            boolean isSimpleFollowing, boolean stopAtFirst ) throws org.xml.sax.SAXException {
        
        //        return super.findDescendants (xpath, execContext, context, opPos, stepType,
        //            subQueryResults, callback, callbackInfo, isSimpleFollowing, stopAtFirst);
        
        int argLen = xpath.getArgLengthOfStep( opPos );
        opPos = xpath.getFirstChildPosOfStep( opPos );
        
        Node savedNode = walker.getCurrentNode();
        Node pos = savedNode;
        
        // If using a document fragment with references (non-standard)
        // we can not use the next-sibling business at the top level.
        if (Node.DOCUMENT_FRAGMENT_NODE != context.getNodeType()) {
            while (null != pos) {
                if (stepType == XPath.FROM_DESCENDANTS_OR_SELF || context != pos) {
                    if (XPath.MATCH_SCORE_NONE != nodeTest( xpath, execContext, pos, opPos, argLen, stepType )) {
                        // subQueryResults.addNode(pos);
                        if (isSimpleFollowing && null != callback) {
                            execContext.incrementContextNodePosition( pos );
                            if (predicate( xpath, execContext, pos, opPos + argLen )) {
                                callback.processLocatedNode( execContext, pos, callbackInfo );
                                if (stopAtFirst) {
                                    break;
                                } 
                            } 
                        } else {
                            subQueryResults = addNode( subQueryResults, pos );
                        } 
                    } 
                } 
                // Node nextNode = pos.getFirstChild();
                Node nextNode = walker.firstChild();
                while (null == nextNode) {
                    if (context.equals( pos )) {
                        break;
                    } 
                    // nextNode = pos.getNextSibling ();
                    nextNode = walker.nextSibling();
                    if (null == nextNode) {
                        // pos = pos.getParentNode();
                        pos = walker.parentNode();
                        if (pos == null || context.equals( pos )) {
                            nextNode = null;
                            break;
                        } 
                    } 
                } 
                pos = nextNode;
            } 
        } else {
            NodeList children = context.getChildNodes();
            int n = children.getLength();
            for (int i = 0; i < n; i++) {
                pos = children.item( i );
                context = pos;
                while (null != pos) {
                    if (stepType == XPath.FROM_DESCENDANTS_OR_SELF || !context.equals( pos )) {
                        if (XPath.MATCH_SCORE_NONE != nodeTest( xpath, execContext, pos, opPos, argLen, stepType )) {
                            if (isSimpleFollowing && null != callback) {
                                execContext.incrementContextNodePosition( pos );
                                if (predicate( xpath, execContext, pos, opPos + argLen )) {
                                    callback.processLocatedNode( execContext, pos, callbackInfo );
                                    if (stopAtFirst) {
                                        break;
                                    } 
                                } 
                            } else {