content: /*
   * 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 mf.org.apache.xerces.dom;
  
  import java.util.ArrayList;
  
  import mf.org.w3c.dom.Node;
  import mf.org.w3c.dom.NodeList;
  
  /**
   * This class implements the DOM's NodeList behavior for
   * Element.getElementsByTagName()
   * <p/>
   * The DOM describes NodeList as follows:
   * <p/>
   * 1) It may represent EITHER nodes scattered through a subtree (when
   * returned by Element.getElementsByTagName), or just the immediate
   * children (when returned by Node.getChildNodes). The latter is easy,
   * but the former (which this class addresses) is more challenging.
   * <p/>
   * 2) Its behavior is "live" -- that is, it always reflects the
   * current state of the document tree. To put it another way, the
   * NodeLists obtained before and after a series of insertions and
   * deletions are effectively identical (as far as the user is
   * concerned, the former has been dynamically updated as the changes
   * have been made).
   * <p/>
   * 3) Its API accesses individual nodes via an integer index, with the
   * listed nodes numbered sequentially in the order that they were
   * found during a preorder depth-first left-to-right search of the tree.
   * (Of course in the case of getChildNodes, depth is not involved.) As
   * nodes are inserted or deleted in the tree, and hence the NodeList,
   * the numbering of nodes that follow them in the NodeList will
   * change.
   * <p/>
   * It is rather painful to support the latter two in the
   * getElementsByTagName case. The current solution is for Nodes to
   * maintain a change count (eventually that may be a Digest instead),
   * which the NodeList tracks and uses to invalidate itself.
   * <p/>
   * Unfortunately, this does _not_ respond efficiently in the case that
   * the dynamic behavior was supposed to address: scanning a tree while
   * it is being extended. That requires knowing which subtrees have
   * changed, which can become an arbitrarily complex problem.
   * <p/>
   * We save some work by filling the ArrayList only as we access the
   * item()s... but I suspect the same users who demanded index-based
   * access will also start by doing a getLength() to control their loop,
   * blowing this optimization out of the water.
   * <p/>
   * NOTE: Level 2 of the DOM will probably _not_ use NodeList for its
   * extended search mechanisms, partly for the reasons just discussed.
   *
   * @version $Id: DeepNodeListImpl.java 778245 2009-05-24 22:27:32Z mrglavas $
   * @xerces.internal
   * @since PR-DOM-Level-1-19980818.
   */
  public class DeepNodeListImpl
          implements NodeList {
  
      //
      // Data
      //
  
      protected NodeImpl rootNode; // Where the search started
      protected String tagName;   // Or "*" to mean all-tags-acceptable
      protected int changes = 0;
      protected ArrayList nodes;
  
      protected String nsName;
      protected boolean enableNS = false;
  
      //
      // Constructors
      //
  
      /**
       * Constructor.
       */
      public DeepNodeListImpl(NodeImpl rootNode, String tagName) {
          this.rootNode = rootNode;
          this.tagName = tagName;
          nodes = new ArrayList();
      }
  
      /**
       * Constructor for Namespace support.
       */
      public DeepNodeListImpl(NodeImpl rootNode,
                              String nsName, String tagName) {
          this(rootNode, tagName);
          this.nsName = (nsName != null && nsName.length() != 0) ? nsName : null;
          enableNS = true;
      }
  
      //
      // NodeList methods
      //
  
      /**
       * Returns the length of the node list.
       */
      @Override
      public int getLength() {
          // Preload all matching elements. (Stops when we run out of subtree!)
          item(java.lang.Integer.MAX_VALUE);
          return nodes.size();
      }
  
      /**
       * Returns the node at the specified index.
       */
      @Override
      public Node item(int index) {
          Node thisNode;
  
          // Tree changed. Do it all from scratch!
          if (rootNode.changes() != changes) {
              nodes = new ArrayList();
              changes = rootNode.changes();
          }
  
          // In the cache
          final int currentSize = nodes.size();
          if (index < currentSize) {
              return (Node) nodes.get(index);
          }
          // Not yet seen
          else {
  
              // Pick up where we left off (Which may be the beginning)
              if (currentSize == 0) {
                  thisNode = rootNode;
              } else {
                  thisNode = (NodeImpl) (nodes.get(currentSize - 1));
              }
  
              // Add nodes up to the one we're looking for
              while (thisNode != null && index >= nodes.size()) {
                  thisNode = nextMatchingElementAfter(thisNode);
                  if (thisNode != null) {
                      nodes.add(thisNode);
                  }
              }
  
              // Either what we want, or null (not avail.)
              return thisNode;
          }
  
      } // item(int):Node
  
      //
      // Protected methods (might be overridden by an extending DOM)
      //
  
      /**
       * Iterative tree-walker. When you have a Parent link, there's often no
       * need to resort to recursion. NOTE THAT only Element nodes are matched
       * since we're specifically supporting getElementsByTagName().
       */
      protected Node nextMatchingElementAfter(Node current) {
  
          Node next;
          while (current != null) {
              // Look down to first child.
              if (current.hasChildNodes()) {
                  current = (current.getFirstChild());
              }
  
              // Look right to sibling (but not from root!)
              else if (current != rootNode && null != (next = current.getNextSibling())) {
                  current = next;
              }
  
              // Look up and right (but not past root!)
              else {
                  next = null;
                  for (; current != rootNode; // Stop when we return to starting point
                       current = current.getParentNode()) {
  
                      next = current.getNextSibling();
                      if (next != null)
                          break;
                  }
                  current = next;
              }
  
              // Have we found an Element with the right tagName?
              // ("*" matches anything.)
              if (current != rootNode
                      && current != null
                      && current.getNodeType() == Node.ELEMENT_NODE) {
                  if (!enableNS) {
                      if (tagName.equals("*") ||
                              ((ElementImpl) current).getTagName().equals(tagName)) {
                          return current;
                      }
                  } else {
                      // DOM2: Namespace logic.
                      if (tagName.equals("*")) {
                          if (nsName != null && nsName.equals("*")) {
                              return current;
                          } else {
                              ElementImpl el = (ElementImpl) current;
                              if ((nsName == null
                                      && el.getNamespaceURI() == null)
                                      || (nsName != null
                                      && nsName.equals(el.getNamespaceURI()))) {
                                  return current;
                              }
                          }
                      } else {
                          ElementImpl el = (ElementImpl) current;
                          if (el.getLocalName() != null
                                  && el.getLocalName().equals(tagName)) {
                              if (nsName != null && nsName.equals("*")) {
                                  return current;
                              } else {
                                  if ((nsName == null
                                          && el.getNamespaceURI() == null)
                                          || (nsName != null &&
                                          nsName.equals(el.getNamespaceURI()))) {
                                      return current;
                                  }
                              }
                          }
                      }
                  }
              }
  
              // Otherwise continue walking the tree
          }
  
          // Fell out of tree-walk; no more instances found
          return null;
  
      } // nextMatchingElementAfter(int):Node
  
  } // class DeepNodeListImpl
  