/*
 * 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 nokogiri.internals.dom2dtm;

import javax.xml.transform.SourceLocator;
import javax.xml.transform.dom.DOMSource;

import org.apache.xml.dtm.DTM;
import org.apache.xml.dtm.DTMManager;
import org.apache.xml.dtm.DTMWSFilter;
import org.apache.xml.dtm.ref.DTMDefaultBaseIterators;
import org.apache.xml.dtm.ref.DTMManagerDefault;
import org.apache.xml.dtm.ref.ExpandedNameTable;
import org.apache.xml.dtm.ref.IncrementalSAXSource;
import org.apache.xml.res.XMLErrorResources;
import org.apache.xml.res.XMLMessages;
import org.apache.xml.utils.FastStringBuffer;
import org.apache.xml.utils.QName;
import org.apache.xml.utils.StringBufferPool;
import org.apache.xml.utils.TreeWalker;
import org.apache.xml.utils.XMLCharacterRecognizer;
import org.apache.xml.utils.XMLString;
import org.apache.xml.utils.XMLStringFactory;
import org.w3c.dom.Attr;
import org.w3c.dom.Document;
import org.w3c.dom.DocumentType;
import org.w3c.dom.Element;
import org.w3c.dom.Entity;
import org.w3c.dom.NamedNodeMap;
import org.w3c.dom.Node;
import org.xml.sax.ContentHandler;

/** The <code>DOM2DTM</code> class serves up a DOM's contents via the
 * DTM API.
 *
 * Note that it doesn't necessarily represent a full Document
 * tree. You can wrap a DOM2DTM around a specific node and its subtree
 * and the right things should happen. (I don't _think_ we currently
 * support DocumentFrgment nodes as roots, though that might be worth
 * considering.)
 *
 * Note too that we do not currently attempt to track document
 * mutation. If you alter the DOM after wrapping DOM2DTM around it,
 * all bets are off.
 * */
public class DOM2DTM extends DTMDefaultBaseIterators
{
//    static final boolean JJK_DEBUG=false;
//    static final boolean JJK_NEWCODE=true;

    /** Manefest constant
     */
    static final String NAMESPACE_DECL_NS="http://www.w3.org/XML/1998/namespace";

    /** The current position in the DOM tree. Last node examined for
     * possible copying to DTM. */
    transient private Node m_pos;
    /** The current position in the DTM tree. Who children get appended to. */
    private int m_last_parent=0;
    /** The current position in the DTM tree. Who children reference as their
     * previous sib. */
    private int m_last_kid=NULL;

    /** The top of the subtree.
     * %REVIEW%: 'may not be the same as m_context if "//foo" pattern.'
     * */
    transient private Node m_root;

    /** True iff the first element has been processed. This is used to control
     synthesis of the implied xml: namespace declaration node. */
    boolean m_processedFirstElement=false;

    /** true if ALL the nodes in the m_root subtree have been processed;
     * false if our incremental build has not yet finished scanning the
     * DOM tree.  */
    transient private boolean m_nodesAreProcessed;

    /** The node objects.  The instance part of the handle indexes
     * directly into this vector.  Each DTM node may actually be
     * composed of several DOM nodes (for example, if logically-adjacent
     * Text/CDATASection nodes in the DOM have been coalesced into a
     * single DTM Text node); this table points only to the first in
     * that sequence. */
    protected final java.util.List<Node> m_nodes = new java.util.ArrayList<Node>(12);

    /**
     * Construct a DOM2DTM object from a DOM node.
     *
     * @param mgr The DTMManager who owns this DTM.
     * @param domSource the DOM source that this DTM will wrap.
     * @param dtmIdentity The DTM identity ID for this DTM.
     * @param whiteSpaceFilter The white space filter for this DTM, which may
     *                         be null.
     * @param xstringfactory XMLString factory for creating character content.
     * @param doIndexing true if the caller considers it worth it to use
     *                   indexing schemes.
     */
    public DOM2DTM(DTMManager mgr, DOMSource domSource,
                   int dtmIdentity, DTMWSFilter whiteSpaceFilter,
                   XMLStringFactory xstringfactory,
                   boolean doIndexing)
    {
        super(mgr, domSource, dtmIdentity, whiteSpaceFilter,
            xstringfactory, doIndexing);

        // Initialize DOM navigation
        m_pos=m_root = domSource.getNode();
        // Initialize DTM navigation
        m_last_parent=m_last_kid=NULL;
        m_last_kid=addNode(m_root, m_last_parent,m_last_kid, NULL);

        // Apparently the domSource root may not actually be the
        // Document node. If it's an Element node, we need to immediately
        // add its attributes. Adapted from nextNode().
        // %REVIEW% Move this logic into addNode and recurse? Cleaner!
        //
        // (If it's an EntityReference node, we're probably in
        // seriously bad trouble. For now
        // I'm just hoping nobody is ever quite that foolish... %REVIEW%)
        //
        // %ISSUE% What about inherited namespaces in this case?
        // Do we need to special-case initialize them into the DTM model?
        if(ELEMENT_NODE == m_root.getNodeType())
        {
            NamedNodeMap attrs=m_root.getAttributes();
            int attrsize=(attrs==null) ? 0 : attrs.getLength();
            if(attrsize>0)
            {
                int attrIndex=NULL; // start with no previous sib
                for(int i=0;i<attrsize;++i)
                {
                    // No need to force nodetype in this case;
                    // addNode() will take care of switching it from
                    // Attr to Namespace if necessary.
                    attrIndex=addNode(attrs.item(i),0,attrIndex,NULL);
                    m_firstch.setElementAt(DTM.NULL,attrIndex);
                }
                // Terminate list of attrs, and make sure they aren't
                // considered children of the element
                m_nextsib.setElementAt(DTM.NULL,attrIndex);

                // IMPORTANT: This does NOT change m_last_parent or m_last_kid!
            } // if attrs exist
        } //if(ELEMENT_NODE)

        // Initialize DTM-completed status
        m_nodesAreProcessed = false;
    }

    /**
     * Construct the node map from the node.
     *
     * @param node The node that is to be added to the DTM.
     * @param parentIndex The current parent index.
     * @param previousSibling The previous sibling index.
     * @param forceNodeType If not DTM.NULL, overrides the DOM node type.
     *	Used to force nodes to Text rather than CDATASection when their
     *	coalesced value includes ordinary Text nodes (current DTM behavior).
     *
     * @return The index identity of the node that was added.
     */
    protected int addNode(Node node, int parentIndex,
                          int previousSibling, int forceNodeType)
    {
        int nodeIndex = m_nodes.size();

        // Have we overflowed a DTM Identity's addressing range?
        if(m_dtmIdent.size() == (nodeIndex>>>DTMManager.IDENT_DTM_NODE_BITS))
        {
            try
            {
                if(m_mgr==null)
                    throw new ClassCastException();

                // Handle as Extended Addressing
                DTMManagerDefault mgrD=(DTMManagerDefault)m_mgr;
                int id=mgrD.getFirstFreeDTMID();
                mgrD.addDTM(this,id,nodeIndex);
                m_dtmIdent.addElement(id<<DTMManager.IDENT_DTM_NODE_BITS);
            }
            catch(ClassCastException e)
            {
                // %REVIEW% Wrong error message, but I've been told we're trying
                // not to add messages right not for I18N reasons.
                // %REVIEW% Should this be a Fatal Error?
                error(XMLMessages.createXMLMessage(XMLErrorResources.ER_NO_DTMIDS_AVAIL, null));//"No more DTM IDs are available";
            }
        }

        m_size++;
        // ensureSize(nodeIndex);

        int type;
        if(NULL==forceNodeType)
            type = node.getNodeType();
        else
            type=forceNodeType;

        // %REVIEW% The Namespace Spec currently says that Namespaces are
        // processed in a non-namespace-aware manner, by matching the
        // QName, even though there is in fact a namespace assigned to
        // these nodes in the DOM. If and when that changes, we will have
        // to consider whether we check the namespace-for-namespaces
        // rather than the node name.
        //
        // %TBD% Note that the DOM does not necessarily explicitly declare
        // all the namespaces it uses. DOM Level 3 will introduce a
        // namespace-normalization operation which reconciles that, and we
        // can request that users invoke it or otherwise ensure that the
        // tree is namespace-well-formed before passing the DOM to Xalan.
        // But if they don't, what should we do about it? We probably
        // don't want to alter the source DOM (and may not be able to do
        // so if it's read-only). The best available answer might be to
        // synthesize additional DTM Namespace Nodes that don't correspond
        // to DOM Attr Nodes.
        if (Node.ATTRIBUTE_NODE == type)
        {
            String name = node.getNodeName();

            if (name.startsWith("xmlns:") || name.equals("xmlns"))
            {
                type = DTM.NAMESPACE_NODE;
            }
        }

        m_nodes.add(node);

        m_firstch.setElementAt(NOTPROCESSED,nodeIndex);
        m_nextsib.setElementAt(NOTPROCESSED,nodeIndex);
        m_prevsib.setElementAt(previousSibling,nodeIndex);
        m_parent.setElementAt(parentIndex,nodeIndex);

        if(DTM.NULL != parentIndex &&
            type != DTM.ATTRIBUTE_NODE &&
            type != DTM.NAMESPACE_NODE)
        {
            // If the DTM parent had no children, this becomes its first child.
            if(NOTPROCESSED == m_firstch.elementAt(parentIndex))
                m_firstch.setElementAt(nodeIndex,parentIndex);
        }

        String nsURI = node.getNamespaceURI();

        // Deal with the difference between Namespace spec and XSLT
        // definitions of local name. (The former says PIs don't have
        // localnames; the latter says they do.)
        String localName =  (type == Node.PROCESSING_INSTRUCTION_NODE) ?
            node.getNodeName() :
            node.getLocalName();

        // Hack to make DOM1 sort of work...
        if(((type == Node.ELEMENT_NODE) || (type == Node.ATTRIBUTE_NODE))
            && null == localName)
            localName = node.getNodeName(); // -sb

        ExpandedNameTable exnt = m_expandedNameTable;

        // %TBD% Nodes created with the old non-namespace-aware DOM
        // calls createElement() and createAttribute() will never have a
        // localname. That will cause their expandedNameID to be just the
        // nodeType... which will keep them from being matched
        // successfully by name. Since the DOM makes no promise that
        // those will participate in namespace processing, this is
        // officially accepted as Not Our Fault. But it might be nice to
        // issue a diagnostic message!
        if(node.getLocalName()==null &&
            (type==Node.ELEMENT_NODE || type==Node.ATTRIBUTE_NODE))
        {
            // warning("DOM 'level 1' node "+node.getNodeName()+" won't be mapped properly in DOM2DTM.");
        }

        int expandedNameID = (null != localName)
            ? exnt.getExpandedTypeID(nsURI, localName, type) :
            exnt.getExpandedTypeID(type);

        m_exptype.setElementAt(expandedNameID,nodeIndex);

        indexNode(expandedNameID, nodeIndex);

        if (DTM.NULL != previousSibling)
            m_nextsib.setElementAt(nodeIndex,previousSibling);

        // This should be done after m_exptype has been set, and probably should
        // always be the last thing we do
        if (type == DTM.NAMESPACE_NODE)
            declareNamespaceInContext(parentIndex,nodeIndex);

        return nodeIndex;
    }

    /**
     * Get the number of nodes that have been added.
     */
    public int getNumberOfNodes()
    {
        return m_nodes.size();
    }

    /**
     * This method iterates to the next node that will be added to the table.
     * Each call to this method adds a new node to the table, unless the end
     * is reached, in which case it returns null.
     *
     * @return The true if a next node is found or false if
     *         there are no more nodes.
     */
    protected boolean nextNode()
    {
        // Non-recursive one-fetch-at-a-time depth-first traversal with
        // attribute/namespace nodes and white-space stripping.
        // Navigating the DOM is simple, navigating the DTM is simple;
        // keeping track of both at once is a trifle baroque but at least
        // we've avoided most of the special cases.
        if (m_nodesAreProcessed)
            return false;

        // %REVIEW% Is this local copy Really Useful from a performance
        // point of view?  Or is this a false microoptimization?
        Node pos=m_pos;
        Node next=null;
        int nexttype=NULL;

        // Navigate DOM tree
        do
        {
            // Look down to first child.
            if (pos.hasChildNodes())
            {
                next = pos.getFirstChild();

                // %REVIEW% There's probably a more elegant way to skip
                // the doctype. (Just let it go and Suppress it?
                if(next!=null && DOCUMENT_TYPE_NODE==next.getNodeType())
                    next=next.getNextSibling();

                // Push DTM context -- except for children of Entity References,
                // which have no DTM equivalent and cause no DTM navigation.
                if(ENTITY_REFERENCE_NODE!=pos.getNodeType())
                {
                    m_last_parent=m_last_kid;
                    m_last_kid=NULL;
                    // Whitespace-handler context stacking
                    if(null != m_wsfilter)
                    {
                        short wsv =
                            m_wsfilter.getShouldStripSpace(makeNodeHandle(m_last_parent),this);
                        boolean shouldStrip = (DTMWSFilter.INHERIT == wsv)
                            ? getShouldStripWhitespace()
                            : (DTMWSFilter.STRIP == wsv);
                        pushShouldStripWhitespace(shouldStrip);
                    } // if(m_wsfilter)
                }
            }

            // If that fails, look up and right (but not past root!)
            else
            {
                if(m_last_kid!=NULL)
                {
                    // Last node posted at this level had no more children
                    // If it has _no_ children, we need to record that.
                    if(m_firstch.elementAt(m_last_kid)==NOTPROCESSED)
                        m_firstch.setElementAt(NULL,m_last_kid);
                }

                while(m_last_parent != NULL)
                {
                    // %REVIEW% There's probably a more elegant way to
                    // skip the doctype. (Just let it go and Suppress it?
                    next = pos.getNextSibling();
                    if(next!=null && DOCUMENT_TYPE_NODE==next.getNodeType())
                        next=next.getNextSibling();

                    if(next!=null)
                        break; // Found it!

                    // No next-sibling found. Pop the DOM.
                    pos=pos.getParentNode();
//                    if(pos==null)
//                    {
//                        // %TBD% Should never arise, but I want to be sure of that...
//                        if(JJK_DEBUG)
//                        {
//                            System.out.println("***** DOM2DTM Pop Control Flow problem");
//                            for(;;); // Freeze right here!
//                        }
//                    }

                    // The only parents in the DTM are Elements.  However,
                    // the DOM could contain EntityReferences.  If we
                    // encounter one, pop it _without_ popping DTM.
                    if(pos!=null && ENTITY_REFERENCE_NODE == pos.getNodeType())
                    {
//                        // Nothing needs doing
//                        if(JJK_DEBUG) System.out.println("***** DOM2DTM popping EntRef");
                    }
                    else
                    {
                        popShouldStripWhitespace();
                        // Fix and pop DTM
                        if(m_last_kid==NULL)
                            m_firstch.setElementAt(NULL,m_last_parent); // Popping from an element
                        else
                            m_nextsib.setElementAt(NULL,m_last_kid); // Popping from anything else
                        m_last_parent=m_parent.elementAt(m_last_kid=m_last_parent);
                    }
                }
                if(m_last_parent==NULL) next=null;
            }

            if(next!=null) nexttype=next.getNodeType();

            // If it's an entity ref, advance past it.
            //
            // %REVIEW% Should we let this out the door and just suppress it?
            // More work, but simpler code, more likely to be correct, and
            // it doesn't happen very often. We'd get rid of the loop too.
            if (ENTITY_REFERENCE_NODE == nexttype) pos=next;
        }
        while (ENTITY_REFERENCE_NODE == nexttype);

        // Did we run out of the tree?
        if(next==null)
        {
            m_nextsib.setElementAt(NULL,0);
            m_nodesAreProcessed = true;
            m_pos=null;

//            if(JJK_DEBUG)
//            {
//                System.out.println("***** DOM2DTM Crosscheck:");
//                for(int i=0;i<m_nodes.size();++i)
//                    System.out.println(i+":\t"+m_firstch.elementAt(i)+"\t"+m_nextsib.elementAt(i));
//            }

            return false;
        }

        // Text needs some special handling:
        //
        // DTM may skip whitespace. This is handled by the suppressNode flag, which
        // when true will keep the DTM node from being created.
        //
        // DTM only directly records the first DOM node of any logically-contiguous
        // sequence. The lastTextNode value will be set to the last node in the
        // contiguous sequence, and -- AFTER the DTM addNode -- can be used to
        // advance next over this whole block. Should be simpler than special-casing
        // the above loop for "Was the logically-preceeding sibling a text node".
        //
        // Finally, a DTM node should be considered a CDATASection only if all the
        // contiguous text it covers is CDATASections. The first Text should
        // force DTM to Text.

        boolean suppressNode=false;
        Node lastTextNode=null;

        nexttype=next.getNodeType();

        // nexttype=pos.getNodeType();
        if(TEXT_NODE == nexttype || CDATA_SECTION_NODE == nexttype)
        {
            // If filtering, initially assume we're going to suppress the node
            suppressNode=((null != m_wsfilter) && getShouldStripWhitespace());

            // Scan logically contiguous text (siblings, plus "flattening"
            // of entity reference boundaries).
            if (suppressNode) {
                Node n = next;
                while (n != null) {
                    lastTextNode=n;
                    // Any Text node means DTM considers it all Text
                    if (TEXT_NODE == n.getNodeType()) nexttype = TEXT_NODE;
                    // Any non-whitespace in this sequence blocks whitespace
                    // suppression
                    suppressNode &= XMLCharacterRecognizer.isWhiteSpace(n.getNodeValue());

                    n = logicalNextDOMTextNode(n);
                }
            }
        }

        // Special handling for PIs: Some DOMs represent the XML
        // Declaration as a PI. This is officially incorrect, per the DOM
        // spec, but is considered a "wrong but tolerable" temporary
        // workaround pending proper handling of these fields in DOM Level
        // 3. We want to recognize and reject that case.
        else if(PROCESSING_INSTRUCTION_NODE==nexttype)
        {
            suppressNode = (pos.getNodeName().toLowerCase().equals("xml"));
        }


        if(!suppressNode)
        {
            // Inserting next. NOTE that we force the node type; for
            // coalesced Text, this records CDATASections adjacent to
            // ordinary Text as Text.
            int nextindex=addNode(next, m_last_parent, m_last_kid, nexttype);

            m_last_kid=nextindex;

            if(ELEMENT_NODE == nexttype)
            {
                int attrIndex=NULL; // start with no previous sib
                // Process attributes _now_, rather than waiting.
                // Simpler control flow, makes NS cache available immediately.
                NamedNodeMap attrs=next.getAttributes();
                int attrsize=(attrs==null) ? 0 : attrs.getLength();
                if(attrsize>0)
                {
                    for(int i=0;i<attrsize;++i)
                    {
                        // No need to force nodetype in this case;
                        // addNode() will take care of switching it from
                        // Attr to Namespace if necessary.
                        attrIndex=addNode(attrs.item(i), nextindex, attrIndex, NULL);
                        m_firstch.setElementAt(DTM.NULL,attrIndex);

                        // If the xml: prefix is explicitly declared
                        // we don't need to synthesize one.
                        //
                        // NOTE that XML Namespaces were not originally
                        // defined as being namespace-aware (grrr), and
                        // while the W3C is planning to fix this it's
                        // safer for now to test the QName and trust the
                        // parsers to prevent anyone from redefining the
                        // reserved xmlns: prefix
                        if(!m_processedFirstElement
                            && "xmlns:xml".equals(attrs.item(i).getNodeName()))
                            m_processedFirstElement=true;
                    }
                    // Terminate list of attrs, and make sure they aren't
                    // considered children of the element
                } // if attrs exist
                if(!m_processedFirstElement)
                {
                    // The DOM might not have an explicit declaration for the
                    // implicit "xml:" prefix, but the XPath data model
                    // requires that this appear as a Namespace Node so we
                    // have to synthesize one. You can think of this as
                    // being a default attribute defined by the XML
                    // Namespaces spec rather than by the DTD.
                    attrIndex=addNode(new DOM2DTMdefaultNamespaceDeclarationNode(
                            (Element)next,"xml",NAMESPACE_DECL_NS,
                            makeNodeHandle(((attrIndex==NULL)?nextindex:attrIndex)+1)
                        ),
                        nextindex,attrIndex,NULL);
                    m_firstch.setElementAt(DTM.NULL,attrIndex);
                    m_processedFirstElement=true;
                }
                if(attrIndex!=NULL) m_nextsib.setElementAt(DTM.NULL,attrIndex);
            } //if(ELEMENT_NODE)
        } // (if !suppressNode)

        // Text postprocessing: Act on values stored above
        //if(TEXT_NODE == nexttype || CDATA_SECTION_NODE == nexttype)
        //{
            // %TBD% If nexttype was forced to TEXT, patch the DTM node
            if (lastTextNode != null) next=lastTextNode;      // Advance the DOM cursor over contiguous text
        //}

        // Remember where we left off.
        m_pos=next;
        return true;
    }


    /**
     * Return an DOM node for the given node.
     *
     * @param nodeHandle The node ID.
     *
     * @return A node representation of the DTM node.
     */
    public Node getNode(int nodeHandle)
    {

        int identity = makeNodeIdentity(nodeHandle);

        return (Node) m_nodes.get(identity);
    }

    /**
     * Get a Node from an identity index.
     *
     * NEEDSDOC @param nodeIdentity
     *
     * NEEDSDOC ($objectName$) @return
     */
    protected Node lookupNode(int nodeIdentity)
    {
        return (Node) m_nodes.get(nodeIdentity);
    }

    /**
     * Get the next node identity value in the list, and call the iterator
     * if it hasn't been added yet.
     *
     * @param identity The node identity (index).
     * @return identity+1, or DTM.NULL.
     */
    protected int getNextNodeIdentity(int identity)
    {

        identity += 1;

        if (identity >= m_nodes.size())
        {
            if (!nextNode())
                identity = DTM.NULL;
        }

        return identity;
    }

    /**
     * Get the handle from a Node.
     * <p>%OPT% This will be pretty slow.</p>
     *
     * <p>%OPT% An XPath-like search (walk up DOM to root, tracking path;
     * walk down DTM reconstructing path) might be considerably faster
     * on later nodes in large documents. That might also imply improving
     * this call to handle nodes which would be in this DTM but
     * have not yet been built, which might or might not be a Good Thing.</p>
     *
     * %REVIEW% This relies on being able to test node-identity via
     * object-identity. DTM2DOM proxying is a great example of a case where
     * that doesn't work. DOM Level 3 will provide the isSameNode() method
     * to fix that, but until then this is going to be flaky.
     *
     * @param node A node, which may be null.
     *
     * @return The node handle or <code>DTM.NULL</code>.
     */
    public int getHandleFromNode(Node node)
    {
        if (null != node)
        {
            int len = m_nodes.size();
            boolean isMore;
            int i = 0;
            do
            {
                for (; i < len; i++)
                {
                    if (m_nodes.get(i) == node)
                        return makeNodeHandle(i);
                }

                isMore = nextNode();

                len = m_nodes.size();

            }
            while(isMore || i < len);
        }

        return DTM.NULL;
    }

    /** Get the handle from a Node. This is a more robust version of
     * getHandleFromNode, intended to be usable by the public.
     *
     * <p>%OPT% This will be pretty slow.</p>
     *
     * %REVIEW% This relies on being able to test node-identity via
     * object-identity. DTM2DOM proxying is a great example of a case where
     * that doesn't work. DOM Level 3 will provide the isSameNode() method
     * to fix that, but until then this is going to be flaky.
     *
     * @param node A node, which may be null.
     *
     * @return The node handle or <code>DTM.NULL</code>.  */
    public int getHandleOfNode(Node node)
    {
        if (null != node)
        {
            // Is Node actually within the same document? If not, don't search!
            // This would be easier if m_root was always the Document node, but
            // we decided to allow wrapping a DTM around a subtree.
            if((m_root==node) ||
                (m_root.getNodeType()==DOCUMENT_NODE &&
                    m_root==node.getOwnerDocument()) ||
                (m_root.getNodeType()!=DOCUMENT_NODE &&
                    m_root.getOwnerDocument()==node.getOwnerDocument())
                )
            {
                // If node _is_ in m_root's tree, find its handle
                //
                // %OPT% This check may be improved significantly when DOM
                // Level 3 nodeKey and relative-order tests become
                // available!
                for(Node cursor=node;
                    cursor!=null;
                    cursor=
                        (cursor.getNodeType()!=ATTRIBUTE_NODE)
                            ? cursor.getParentNode()
                            : ((org.w3c.dom.Attr)cursor).getOwnerElement())
                {
                    if(cursor==m_root)
                        // We know this node; find its handle.
                        return getHandleFromNode(node);
                } // for ancestors of node
            } // if node and m_root in same Document
        } // if node!=null

        return DTM.NULL;
    }

    /**
     * Retrieves an attribute node by by qualified name and namespace URI.
     *
     * @param nodeHandle int Handle of the node upon which to look up this attribute..
     * @param namespaceURI The namespace URI of the attribute to
     *   retrieve, or null.
     * @param name The local name of the attribute to
     *   retrieve.
     * @return The attribute node handle with the specified name (
     *   <code>nodeName</code>) or <code>DTM.NULL</code> if there is no such
     *   attribute.
     */
    public int getAttributeNode(int nodeHandle, String namespaceURI,
                                String name)
    {

        // %OPT% This is probably slower than it needs to be.
        if (null == namespaceURI)
            namespaceURI = "";

        int type = getNodeType(nodeHandle);

        if (DTM.ELEMENT_NODE == type)
        {

            // Assume that attributes immediately follow the element.
            int identity = makeNodeIdentity(nodeHandle);

            while (DTM.NULL != (identity = getNextNodeIdentity(identity)))
            {
                // Assume this can not be null.
                type = _type(identity);

                // %REVIEW%
                // Should namespace nodes be retrievable DOM-style as attrs?
                // If not we need a separate function... which may be desirable
                // architecturally, but which is ugly from a code point of view.
                // (If we REALLY insist on it, this code should become a subroutine
                // of both -- retrieve the node, then test if the type matches
                // what you're looking for.)
                if (type == DTM.ATTRIBUTE_NODE || type==DTM.NAMESPACE_NODE)
                {
                    Node node = lookupNode(identity);
                    String nodeuri = node.getNamespaceURI();

                    if (null == nodeuri)
                        nodeuri = "";

                    String nodelocalname = node.getLocalName();

                    if (nodeuri.equals(namespaceURI) && name.equals(nodelocalname))
                        return makeNodeHandle(identity);
                }

                else // if (DTM.NAMESPACE_NODE != type)
                {
                    break;
                }
            }
        }

        return DTM.NULL;
    }

    /**
     * Get the string-value of a node as a String object
     * (see http://www.w3.org/TR/xpath#data-model
     * for the definition of a node's string-value).
     *
     * @param nodeHandle The node ID.
     *
     * @return A string object that represents the string-value of the given node.
     */
    public XMLString getStringValue(int nodeHandle)
    {

        int type = getNodeType(nodeHandle);
        Node node = getNode(nodeHandle);
        // %TBD% If an element only has one text node, we should just use it
        // directly.
        if(DTM.ELEMENT_NODE == type || DTM.DOCUMENT_NODE == type
            || DTM.DOCUMENT_FRAGMENT_NODE == type)
        {
            FastStringBuffer buf = StringBufferPool.get();
            String s;

            try
            {
                getNodeData(node, buf);

                s = (buf.length() > 0) ? buf.toString() : "";
            }
            finally
            {
                StringBufferPool.free(buf);
            }

            return m_xstrf.newstr( s );
        }
        else if(TEXT_NODE == type || CDATA_SECTION_NODE == type)
        {
            // If this is a DTM text node, it may be made of multiple DOM text
            // nodes -- including navigating into Entity References. DOM2DTM
            // records the first node in the sequence and requires that we
            // pick up the others when we retrieve the DTM node's value.
            //
            // %REVIEW% DOM Level 3 is expected to add a "whole text"
            // retrieval method which performs this function for us.
            FastStringBuffer buf = StringBufferPool.get();
            while(node!=null)
            {
                buf.append(node.getNodeValue());
                node=logicalNextDOMTextNode(node);
            }
            String s=(buf.length() > 0) ? buf.toString() : "";
            StringBufferPool.free(buf);
            return m_xstrf.newstr( s );
        }
        else
            return m_xstrf.newstr( node.getNodeValue() );
    }

    /**
     * Determine if the string-value of a node is whitespace
     *
     * @param nodeHandle The node Handle.
     *
     * @return Return true if the given node is whitespace.
     */
    public boolean isWhitespace(int nodeHandle)
    {
        int type = getNodeType(nodeHandle);
        Node node = getNode(nodeHandle);
        if(TEXT_NODE == type || CDATA_SECTION_NODE == type)
        {
            // If this is a DTM text node, it may be made of multiple DOM text
            // nodes -- including navigating into Entity References. DOM2DTM
            // records the first node in the sequence and requires that we
            // pick up the others when we retrieve the DTM node's value.
            //
            // %REVIEW% DOM Level 3 is expected to add a "whole text"
            // retrieval method which performs this function for us.
            FastStringBuffer buf = StringBufferPool.get();
            while(node!=null)
            {
                buf.append(node.getNodeValue());
                node=logicalNextDOMTextNode(node);
            }
            boolean b = buf.isWhitespace(0, buf.length());
            StringBufferPool.free(buf);
            return b;
        }
        return false;
    }

    /**
     * Retrieve the text content of a DOM subtree, appending it into a
     * user-supplied FastStringBuffer object. Note that attributes are
     * not considered part of the content of an element.
     * <p>
     * There are open questions regarding whitespace stripping.
     * Currently we make no special effort in that regard, since the standard
     * DOM doesn't yet provide DTD-based information to distinguish
     * whitespace-in-element-context from genuine #PCDATA. Note that we
     * should probably also consider xml:space if/when we address this.
     * DOM Level 3 may solve the problem for us.
     * <p>
     * %REVIEW% Actually, since this method operates on the DOM side of the
     * fence rather than the DTM side, it SHOULDN'T do
     * any special handling. The DOM does what the DOM does; if you want
     * DTM-level abstractions, use DTM-level methods.
     *
     * @param node Node whose subtree is to be walked, gathering the
     * contents of all Text or CDATASection nodes.
     * @param buf FastStringBuffer into which the contents of the text
     * nodes are to be concatenated.
     */
    protected static void getNodeData(Node node, FastStringBuffer buf)
    {

        switch (node.getNodeType())
        {
            case Node.DOCUMENT_FRAGMENT_NODE :
            case Node.DOCUMENT_NODE :
            case Node.ELEMENT_NODE :
            {
                for (Node child = node.getFirstChild(); null != child;
                     child = child.getNextSibling())
                {
                    getNodeData(child, buf);
                }
            }
            break;
            case Node.TEXT_NODE :
            case Node.CDATA_SECTION_NODE :
            case Node.ATTRIBUTE_NODE :	// Never a child but might be our starting node
                buf.append(node.getNodeValue());
                break;
            case Node.PROCESSING_INSTRUCTION_NODE :
                // warning(XPATHErrorResources.WG_PARSING_AND_PREPARING);
                break;
            default :
                // ignore
                break;
        }
    }

    /**
     * Given a node handle, return its DOM-style node name. This will
     * include names such as #text or #document.
     *
     * @param nodeHandle the id of the node.
     * @return String Name of this node, which may be an empty string.
     * %REVIEW% Document when empty string is possible...
     * %REVIEW-COMMENT% It should never be empty, should it?
     */
    public String getNodeName(int nodeHandle)
    {

        Node node = getNode(nodeHandle);

        // Assume non-null.
        return node.getNodeName();
    }

    /**
     * Given a node handle, return the XPath node name.  This should be
     * the name as described by the XPath data model, NOT the DOM-style
     * name.
     *
     * @param nodeHandle the id of the node.
     * @return String Name of this node, which may be an empty string.
     */
    public String getNodeNameX(int nodeHandle)
    {

        String name;
        short type = getNodeType(nodeHandle);

        switch (type)
        {
            case DTM.NAMESPACE_NODE :
            {
                Node node = getNode(nodeHandle);

                // assume not null.
                name = node.getNodeName();
                if(name.startsWith("xmlns:"))
                {
                    name = QName.getLocalPart(name);
                }
                else if(name.equals("xmlns"))
                {
                    name = "";
                }
            }
            break;
            case DTM.ATTRIBUTE_NODE :
            case DTM.ELEMENT_NODE :
            case DTM.ENTITY_REFERENCE_NODE :
            case DTM.PROCESSING_INSTRUCTION_NODE :
            {
                Node node = getNode(nodeHandle);

                // assume not null.
                name = node.getNodeName();
            }
            break;
            default :
                name = "";
        }

        return name;
    }

    /**
     * Given a node handle, return its XPath-style localname.
     * (As defined in Namespaces, this is the portion of the name after any
     * colon character).
     *
     * @param nodeHandle the id of the node.
     * @return String Local name of this node.
     */
    public String getLocalName(int nodeHandle)
    {
//        if(JJK_NEWCODE)
//        {
            int id=makeNodeIdentity(nodeHandle);
            if(NULL==id) return null;
            Node newnode=(Node)m_nodes.get(id);
            String newname=newnode.getLocalName();
            if (null == newname)
            {
                // XSLT treats PIs, and possibly other things, as having QNames.
                String qname = newnode.getNodeName();
                if('#'==qname.charAt(0))
                {
                    //  Match old default for this function
                    // This conversion may or may not be necessary
                    newname="";
                }
                else
                {
                    int index = qname.indexOf(':');
                    newname = (index < 0) ? qname : qname.substring(index + 1);
                }
            }
            return newname;
//        }
//        else
//        {
//            String name;
//            short type = getNodeType(nodeHandle);
//            switch (type)
//            {
//                case DTM.ATTRIBUTE_NODE :
//                case DTM.ELEMENT_NODE :
//                case DTM.ENTITY_REFERENCE_NODE :
//                case DTM.NAMESPACE_NODE :
//                case DTM.PROCESSING_INSTRUCTION_NODE :
//                {
//                    Node node = getNode(nodeHandle);
//
//                    // assume not null.
//                    name = node.getLocalName();
//
//                    if (null == name)
//                    {
//                        String qname = node.getNodeName();
//                        int index = qname.indexOf(':');
//
//                        name = (index < 0) ? qname : qname.substring(index + 1);
//                    }
//                }
//                break;
//                default :
//                    name = "";
//            }
//            return name;
//        }
    }

    /**
     * Given a namespace handle, return the prefix that the namespace decl is
     * mapping.
     * Given a node handle, return the prefix used to map to the namespace.
     *
     * <p> %REVIEW% Are you sure you want "" for no prefix?  </p>
     * <p> %REVIEW-COMMENT% I think so... not totally sure. -sb  </p>
     *
     * @param nodeHandle the id of the node.
     * @return String prefix of this node's name, or "" if no explicit
     * namespace prefix was given.
     */
    public String getPrefix(int nodeHandle)
    {

        String prefix;
        short type = getNodeType(nodeHandle);

        switch (type)
        {
            case DTM.NAMESPACE_NODE :
            {
                Node node = getNode(nodeHandle);

                // assume not null.
                String qname = node.getNodeName();
                int index = qname.indexOf(':');

                prefix = (index < 0) ? "" : qname.substring(index + 1);
            }
            break;
            case DTM.ATTRIBUTE_NODE :
            case DTM.ELEMENT_NODE :
            {
                Node node = getNode(nodeHandle);

                // assume not null.
                String qname = node.getNodeName();
                int index = qname.indexOf(':');

                prefix = (index < 0) ? "" : qname.substring(0, index);
            }
            break;
            default :
                prefix = "";
        }

        return prefix;
    }

    /**
     * Given a node handle, return its DOM-style namespace URI
     * (As defined in Namespaces, this is the declared URI which this node's
     * prefix -- or default in lieu thereof -- was mapped to.)
     *
     * <p>%REVIEW% Null or ""? -sb</p>
     *
     * @param nodeHandle the id of the node.
     * @return String URI value of this node's namespace, or null if no
     * namespace was resolved.
     */
    public String getNamespaceURI(int nodeHandle)
    {
//        if(JJK_NEWCODE)
//        {
            int id=makeNodeIdentity(nodeHandle);
            if(id==NULL) return null;
            Node node=(Node)m_nodes.get(id);
            return node.getNamespaceURI();
//        }
//        else
//        {
//            String nsuri;
//            short type = getNodeType(nodeHandle);
//
//            switch (type)
//            {
//                case DTM.ATTRIBUTE_NODE :
//                case DTM.ELEMENT_NODE :
//                case DTM.ENTITY_REFERENCE_NODE :
//                case DTM.NAMESPACE_NODE :
//                case DTM.PROCESSING_INSTRUCTION_NODE :
//                {
//                    Node node = getNode(nodeHandle);
//
//                    // assume not null.
//                    nsuri = node.getNamespaceURI();
//
//                    // %TBD% Handle DOM1?
//                }
//                break;
//                default :
//                    nsuri = null;
//            }
//
//            return nsuri;
//        }
    }

    /** Utility function: Given a DOM Text node, determine whether it is
     * logically followed by another Text or CDATASection node. This may
     * involve traversing into Entity References.
     *
     * %REVIEW% DOM Level 3 is expected to add functionality which may
     * allow us to retire this.
     */
    private Node logicalNextDOMTextNode(Node n)
    {
        Node p=n.getNextSibling();
        if(p==null)
        {
            // Walk out of any EntityReferenceNodes that ended with text
            for(n=n.getParentNode();
                n!=null && ENTITY_REFERENCE_NODE == n.getNodeType();
                n=n.getParentNode())
            {
                p=n.getNextSibling();
                if(p!=null)
                    break;
            }
        }
        n=p;
        while(n!=null && ENTITY_REFERENCE_NODE == n.getNodeType())
        {
            // Walk into any EntityReferenceNodes that start with text
            if(n.hasChildNodes())
                n=n.getFirstChild();
            else
                n=n.getNextSibling();
        }
        if(n!=null)
        {
            // Found a logical next sibling. Is it text?
            int ntype=n.getNodeType();
            if(TEXT_NODE != ntype && CDATA_SECTION_NODE != ntype)
                n=null;
        }
        return n;
    }

    /**
     * Given a node handle, return its node value. This is mostly
     * as defined by the DOM, but may ignore some conveniences.
     * <p>
     *
     * @param nodeHandle The node id.
     * @return String Value of this node, or null if not
     * meaningful for this node type.
     */
    public String getNodeValue(int nodeHandle)
    {
        // The _type(nodeHandle) call was taking the lion's share of our
        // time, and was wrong anyway since it wasn't coverting handle to
        // identity. Inlined it.
        int type = _exptype(makeNodeIdentity(nodeHandle));
        type=(NULL != type) ? getNodeType(nodeHandle) : NULL;

        if(TEXT_NODE!=type && CDATA_SECTION_NODE!=type)
            return getNode(nodeHandle).getNodeValue();

        // If this is a DTM text node, it may be made of multiple DOM text
        // nodes -- including navigating into Entity References. DOM2DTM
        // records the first node in the sequence and requires that we
        // pick up the others when we retrieve the DTM node's value.
        //
        // %REVIEW% DOM Level 3 is expected to add a "whole text"
        // retrieval method which performs this function for us.
        Node node = getNode(nodeHandle);
        Node n=logicalNextDOMTextNode(node);
        if(n==null)
            return node.getNodeValue();

        FastStringBuffer buf = StringBufferPool.get();
        buf.append(node.getNodeValue());
        while(n!=null)
        {
            buf.append(n.getNodeValue());
            n=logicalNextDOMTextNode(n);
        }
        String s = (buf.length() > 0) ? buf.toString() : "";
        StringBufferPool.free(buf);
        return s;
    }

    /**
     *   A document type declaration information item has the following properties:
     *
     *     1. [system identifier] The system identifier of the external subset, if
     *        it exists. Otherwise this property has no value.
     *
     * @return the system identifier String object, or null if there is none.
     */
    public String getDocumentTypeDeclarationSystemIdentifier()
    {

        Document doc;

        if (m_root.getNodeType() == Node.DOCUMENT_NODE)
            doc = (Document) m_root;
        else
            doc = m_root.getOwnerDocument();

        if (null != doc)
        {
            DocumentType dtd = doc.getDoctype();

            if (null != dtd)
            {
                return dtd.getSystemId();
            }
        }

        return null;
    }

    /**
     * Return the public identifier of the external subset,
     * normalized as described in 4.2.2 External Entities [XML]. If there is
     * no external subset or if it has no public identifier, this property
     * has no value.
     *
     * @return the public identifier String object, or null if there is none.
     */
    public String getDocumentTypeDeclarationPublicIdentifier()
    {

        Document doc;

        if (m_root.getNodeType() == Node.DOCUMENT_NODE)
            doc = (Document) m_root;
        else
            doc = m_root.getOwnerDocument();

        if (null != doc)
        {
            DocumentType dtd = doc.getDoctype();

            if (null != dtd)
            {
                return dtd.getPublicId();
            }
        }

        return null;
    }

    /**
     * Returns the <code>Element</code> whose <code>ID</code> is given by
     * <code>elementId</code>. If no such element exists, returns
     * <code>DTM.NULL</code>. Behavior is not defined if more than one element
     * has this <code>ID</code>. Attributes (including those
     * with the name "ID") are not of type ID unless so defined by DTD/Schema
     * information available to the DTM implementation.
     * Implementations that do not know whether attributes are of type ID or
     * not are expected to return <code>DTM.NULL</code>.
     *
     * <p>%REVIEW% Presumably IDs are still scoped to a single document,
     * and this operation searches only within a single document, right?
     * Wouldn't want collisions between DTMs in the same process.</p>
     *
     * @param elementId The unique <code>id</code> value for an element.
     * @return The handle of the matching element.
     */
    public int getElementById(String elementId)
    {

        Document doc = (m_root.getNodeType() == Node.DOCUMENT_NODE)
            ? (Document) m_root : m_root.getOwnerDocument();

        if(null != doc)
        {
            Node elem = doc.getElementById(elementId);
            if(null != elem)
            {
                int elemHandle = getHandleFromNode(elem);

                if(DTM.NULL == elemHandle)
                {
                    int identity = m_nodes.size()-1;
                    while (DTM.NULL != (identity = getNextNodeIdentity(identity)))
                    {
                        Node node = getNode(identity);
                        if(node == elem)
                        {
                            elemHandle = getHandleFromNode(elem);
                            break;
                        }
                    }
                }

                return elemHandle;
            }

        }
        return DTM.NULL;
    }

    /**
     * The getUnparsedEntityURI function returns the URI of the unparsed
     * entity with the specified name in the same document as the context
     * node (see [3.3 Unparsed Entities]). It returns the empty string if
     * there is no such entity.
     * <p>
     * XML processors may choose to use the System Identifier (if one
     * is provided) to resolve the entity, rather than the URI in the
     * Public Identifier. The details are dependent on the processor, and
     * we would have to support some form of plug-in resolver to handle
     * this properly. Currently, we simply return the System Identifier if
     * present, and hope that it a usable URI or that our caller can
     * map it to one.
     * TODO: Resolve Public Identifiers... or consider changing function name.
     * <p>
     * If we find a relative URI
     * reference, XML expects it to be resolved in terms of the base URI
     * of the document. The DOM doesn't do that for us, and it isn't
     * entirely clear whether that should be done here; currently that's
     * pushed up to a higher level of our application. (Note that DOM Level
     * 1 didn't store the document's base URI.)
     * TODO: Consider resolving Relative URIs.
     * <p>
     * (The DOM's statement that "An XML processor may choose to
     * completely expand entities before the structure model is passed
     * to the DOM" refers only to parsed entities, not unparsed, and hence
     * doesn't affect this function.)
     *
     * @param name A string containing the Entity Name of the unparsed
     * entity.
     *
     * @return String containing the URI of the Unparsed Entity, or an
     * empty string if no such entity exists.
     */
    public String getUnparsedEntityURI(String name)
    {

        String url = "";
        Document doc = (m_root.getNodeType() == Node.DOCUMENT_NODE)
            ? (Document) m_root : m_root.getOwnerDocument();

        if (null != doc)
        {
            DocumentType doctype = doc.getDoctype();

            if (null != doctype)
            {
                NamedNodeMap entities = doctype.getEntities();
                if(null == entities)
                    return url;
                Entity entity = (Entity) entities.getNamedItem(name);
                if(null == entity)
                    return url;

                String notationName = entity.getNotationName();

                if (null != notationName)  // then it's unparsed
                {
                    // The draft says: "The XSLT processor may use the public
                    // identifier to generate a URI for the entity instead of the URI
                    // specified in the system identifier. If the XSLT processor does
                    // not use the public identifier to generate the URI, it must use
                    // the system identifier; if the system identifier is a relative
                    // URI, it must be resolved into an absolute URI using the URI of
                    // the resource containing the entity declaration as the base
                    // URI [RFC2396]."
                    // So I'm falling a bit short here.
                    url = entity.getSystemId();

                    if (null == url)
                    {
                        url = entity.getPublicId();
                    }
                    else
                    {
                        // This should be resolved to an absolute URL, but that's hard
                        // to do from here.
                    }
                }
            }
        }

        return url;
    }

    /**
     *     5. [specified] A flag indicating whether this attribute was actually
     *        specified in the start-tag of its element, or was defaulted from the
     *        DTD.
     *
     * @param attributeHandle the attribute handle
     * @return <code>true</code> if the attribute was specified;
     *         <code>false</code> if it was defaulted.
     */
    public boolean isAttributeSpecified(int attributeHandle)
    {
        int type = getNodeType(attributeHandle);

        if (DTM.ATTRIBUTE_NODE == type)
        {
            Attr attr = (Attr)getNode(attributeHandle);
            return attr.getSpecified();
        }
        return false;
    }

    /** Bind an IncrementalSAXSource to this DTM. NOT RELEVANT for DOM2DTM, since
     * we're wrapped around an existing DOM.
     *
     * @param source The IncrementalSAXSource that we want to recieve events from
     * on demand.
     */
    public void setIncrementalSAXSource(IncrementalSAXSource source)
    {
    }

    /** getContentHandler returns "our SAX builder" -- the thing that
     * someone else should send SAX events to in order to extend this
     * DTM model.
     *
     * @return null if this model doesn't respond to SAX events,
     * "this" if the DTM object has a built-in SAX ContentHandler,
     * the IncrmentalSAXSource if we're bound to one and should receive
     * the SAX stream via it for incremental build purposes...
     * */
    public org.xml.sax.ContentHandler getContentHandler()
    {
        return null;
    }

    /**
     * Return this DTM's lexical handler.
     *
     * %REVIEW% Should this return null if constrution already done/begun?
     *
     * @return null if this model doesn't respond to lexical SAX events,
     * "this" if the DTM object has a built-in SAX ContentHandler,
     * the IncrementalSAXSource if we're bound to one and should receive
     * the SAX stream via it for incremental build purposes...
     */
    public org.xml.sax.ext.LexicalHandler getLexicalHandler()
    {

        return null;
    }


    /**
     * Return this DTM's EntityResolver.
     *
     * @return null if this model doesn't respond to SAX entity ref events.
     */
    public org.xml.sax.EntityResolver getEntityResolver()
    {

        return null;
    }

    /**
     * Return this DTM's DTDHandler.
     *
     * @return null if this model doesn't respond to SAX dtd events.
     */
    public org.xml.sax.DTDHandler getDTDHandler()
    {

        return null;
    }

    /**
     * Return this DTM's ErrorHandler.
     *
     * @return null if this model doesn't respond to SAX error events.
     */
    public org.xml.sax.ErrorHandler getErrorHandler()
    {

        return null;
    }

    /**
     * Return this DTM's DeclHandler.
     *
     * @return null if this model doesn't respond to SAX Decl events.
     */
    public org.xml.sax.ext.DeclHandler getDeclHandler()
    {

        return null;
    }

    /** @return true iff we're building this model incrementally (eg
     * we're partnered with a IncrementalSAXSource) and thus require that the
     * transformation and the parse run simultaneously. Guidance to the
     * DTMManager.
     * */
    public boolean needsTwoThreads()
    {
        return false;
    }

    // ========== Direct SAX Dispatch, for optimization purposes ========

    /**
     * Returns whether the specified <var>ch</var> conforms to the XML 1.0 definition
     * of whitespace.  Refer to <A href="http://www.w3.org/TR/1998/REC-xml-19980210#NT-S">
     * the definition of <CODE>S</CODE></A> for details.
     * @param   ch      Character to check as XML whitespace.
     * @return          =true if <var>ch</var> is XML whitespace; otherwise =false.
     */
    private static boolean isSpace(char ch)
    {
        return XMLCharacterRecognizer.isWhiteSpace(ch);  // Take the easy way out for now.
    }

    /**
     * Directly call the
     * characters method on the passed ContentHandler for the
     * string-value of the given node (see http://www.w3.org/TR/xpath#data-model
     * for the definition of a node's string-value). Multiple calls to the
     * ContentHandler's characters methods may well occur for a single call to
     * this method.
     *
     * @param nodeHandle The node ID.
     * @param ch A non-null reference to a ContentHandler.
     *
     * @throws org.xml.sax.SAXException
     */
    public void dispatchCharactersEvents(
        int nodeHandle, org.xml.sax.ContentHandler ch,
        boolean normalize)
        throws org.xml.sax.SAXException
    {
        if(normalize)
        {
            XMLString str = getStringValue(nodeHandle);
            str = str.fixWhiteSpace(true, true, false);
            str.dispatchCharactersEvents(ch);
        }
        else
        {
            int type = getNodeType(nodeHandle);
            Node node = getNode(nodeHandle);
            dispatchNodeData(node, ch, 0);
            // Text coalition -- a DTM text node may represent multiple
            // DOM nodes.
            if(TEXT_NODE == type || CDATA_SECTION_NODE == type)
            {
                while( null != (node=logicalNextDOMTextNode(node)) )
                {
                    dispatchNodeData(node, ch, 0);
                }
            }
        }
    }

    /**
     * Retrieve the text content of a DOM subtree, appending it into a
     * user-supplied FastStringBuffer object. Note that attributes are
     * not considered part of the content of an element.
     * <p>
     * There are open questions regarding whitespace stripping.
     * Currently we make no special effort in that regard, since the standard
     * DOM doesn't yet provide DTD-based information to distinguish
     * whitespace-in-element-context from genuine #PCDATA. Note that we
     * should probably also consider xml:space if/when we address this.
     * DOM Level 3 may solve the problem for us.
     * <p>
     * %REVIEW% Note that as a DOM-level operation, it can be argued that this
     * routine _shouldn't_ perform any processing beyond what the DOM already
     * does, and that whitespace stripping and so on belong at the DTM level.
     * If you want a stripped DOM view, wrap DTM2DOM around DOM2DTM.
     *
     * @param node Node whose subtree is to be walked, gathering the
     * contents of all Text or CDATASection nodes.
     */
    protected static void dispatchNodeData(Node node,
                                           org.xml.sax.ContentHandler ch,
                                           int depth)
        throws org.xml.sax.SAXException
    {

        switch (node.getNodeType())
        {
            case Node.DOCUMENT_FRAGMENT_NODE :
            case Node.DOCUMENT_NODE :
            case Node.ELEMENT_NODE :
            {
                for (Node child = node.getFirstChild(); null != child;
                     child = child.getNextSibling())
                {
                    dispatchNodeData(child, ch, depth+1);
                }
            }
            break;
            case Node.PROCESSING_INSTRUCTION_NODE : // %REVIEW%
            case Node.COMMENT_NODE :
                if(0 != depth)
                    break;
                // NOTE: Because this operation works in the DOM space, it does _not_ attempt
                // to perform Text Coalition. That should only be done in DTM space.
            case Node.TEXT_NODE :
            case Node.CDATA_SECTION_NODE :
            case Node.ATTRIBUTE_NODE :
                String str = node.getNodeValue();
                if(ch instanceof org.apache.xml.dtm.ref.dom2dtm.DOM2DTM.CharacterNodeHandler)
                {
                    ((org.apache.xml.dtm.ref.dom2dtm.DOM2DTM.CharacterNodeHandler)ch).characters(node);
                }
                else
                {
                    ch.characters(str.toCharArray(), 0, str.length());
                }
                break;
//    /* case Node.PROCESSING_INSTRUCTION_NODE :
//      // warning(XPATHErrorResources.WG_PARSING_AND_PREPARING);
//      break; */
            default :
                // ignore
                break;
        }
    }

    TreeWalker m_walker = new TreeWalker(null);

    /**
     * Directly create SAX parser events from a subtree.
     *
     * @param nodeHandle The node ID.
     * @param ch A non-null reference to a ContentHandler.
     *
     * @throws org.xml.sax.SAXException
     */
    public void dispatchToEvents(int nodeHandle, org.xml.sax.ContentHandler ch)
        throws org.xml.sax.SAXException
    {
        TreeWalker treeWalker = m_walker;
        ContentHandler prevCH = treeWalker.getContentHandler();

        if(null != prevCH)
        {
            treeWalker = new TreeWalker(null);
        }
        treeWalker.setContentHandler(ch);

        try
        {
            Node node = getNode(nodeHandle);
            treeWalker.traverseFragment(node);
        }
        finally
        {
            treeWalker.setContentHandler(null);
        }
    }

    /**
     * For the moment all the run time properties are ignored by this
     * class.
     *
     * @param property a <code>String</code> value
     * @param value an <code>Object</code> value
     */
    public void setProperty(String property, Object value)
    {
    }

    /**
     * No source information is available for DOM2DTM, so return
     * <code>null</code> here.
     *
     * @param node an <code>int</code> value
     * @return null
     */
    public SourceLocator getSourceLocatorFor(int node)
    {
        return null;
    }

}