treewalkerimpl.java

来自「JAVA的一些源码 JAVA2 STANDARD EDITION DEVELO」· Java 代码 · 共 544 行 · 第 1/2 页

        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;
            }
        }
    } 
}