elementstack.java

Java的面向对象数据库系统的源代码

/*
 * Copyright 2001 (C) MetaStuff, Ltd. All Rights Reserved.
 * 
 * This software is open source. 
 * See the bottom of this file for the licence.
 * 
 * $Id: ElementStack.java,v 1.2 2003/06/10 16:18:34 per_nyfelt Exp $
 */

package org.dom4j.io;

import org.dom4j.Element;
import org.dom4j.ElementHandler;
import org.dom4j.ElementPath;

/** <p><code>ElementStack</code> is used internally inside the 
  * {@link SAXContentHandler} to maintain a stack of {@link Element} 
  * instances. 
  * It opens an integration possibility allowing derivations to prune the tree
  * when a node is complete.</p>
  *
  * @author <a href="mailto:[e-mail]">James Strachan</a>
  * @version $Revision: 1.2 $
  */
class ElementStack implements ElementPath {

    /** stack of <code>Element</code> objects */
    protected Element[] stack;
    
    /** index of the item at the top of the stack or -1 if the stack is empty */
    protected int lastElementIndex = -1;
    
    private DispatchHandler handler = null;

    
    public ElementStack() {
        this(50);
    }
    
    public ElementStack(int defaultCapacity) {
        stack = new Element[defaultCapacity];
    }
    
    public void setDispatchHandler(DispatchHandler handler)
    {
        this.handler = handler;   
    }
    
    /** Peeks at the top element on the stack without changing the contents
      * of the stack.
      * 
      * sets the current element on the stack
      */
    public void clear() {
        lastElementIndex = -1;
    }
    
    /** Peeks at the top element on the stack without changing the contents
      * of the stack.
      * 
      * @return the current element on the stack 
      */
    public Element peekElement() {
        if ( lastElementIndex < 0 ) { 
            return null;
        }
        return stack[ lastElementIndex ];
    }
    
    /** Pops the element off the stack
      *
      * @return the element that has just been popped off the stack 
      */
    public Element popElement() {
        if ( lastElementIndex < 0 ) { 
            return null;
        }
        return stack[ lastElementIndex-- ];
    }
    
    /** Pushes a new element onto the stack
      * 
      * pushes the new element onto the stack and add it to its parent
      * if there is one.
      */
    public void pushElement(Element element) {
        int length = stack.length;
        if ( ++lastElementIndex >= length ) {
            reallocate( length * 2 );
        }
        stack[lastElementIndex] = element;
    }
    
    /** Reallocates the stack to the given size
      */
    protected void reallocate( int size ) {
        Element[] oldStack = stack;
        stack = new Element[ size ];
        System.arraycopy( oldStack, 0, stack, 0, oldStack.length );
    }
    
    // The ElementPath Interface
    //
    public int size()
    {
        return lastElementIndex + 1;
    }
    
    public Element getElement(int depth)
    {
        Element element;
        try {
            element = (Element)stack[depth];   
        }
        catch (ArrayIndexOutOfBoundsException e)
        {
            element = null;   
        }
        return element;
    }
    
    public String getPath()
    {
        if (handler == null) {
            setDispatchHandler(new DispatchHandler());
        }
        return handler.getPath();
    }
    
    public Element getCurrent()
    {
        return peekElement();   
    }
    
    public void addHandler(String path, ElementHandler handler) {
        this.handler.addHandler(getHandlerPath(path), handler);
    }
    
    public void removeHandler(String path) {
        this.handler.removeHandler(getHandlerPath(path));
    }
    
    private String getHandlerPath(String path) {
        String handlerPath;
        if (this.handler == null) {
            setDispatchHandler(new DispatchHandler());
        }
        if (path.startsWith("/")) {
            handlerPath = path;   
        }
        else if (getPath().equals("/")) {
            handlerPath = getPath() + path;
        }
        else {
            handlerPath = getPath() + "/" + path;   
        }
        return handlerPath;
    }
}




/*
 * Redistribution and use of this software and associated documentation
 * ("Software"), with or without modification, are permitted provided
 * that the following conditions are met:
 *
 * 1. Redistributions of source code must retain copyright
 *    statements and notices.  Redistributions must also contain a
 *    copy of this document.
 *
 * 2. Redistributions in binary form must reproduce the
 *    above copyright notice, this list of conditions and the
 *    following disclaimer in the documentation and/or other
 *    materials provided with the distribution.
 *
 * 3. The name "DOM4J" must not be used to endorse or promote
 *    products derived from this Software without prior written
 *    permission of MetaStuff, Ltd.  For written permission,
 *    please contact [e-mail].
 *
 * 4. Products derived from this Software may not be called "DOM4J"
 *    nor may "DOM4J" appear in their names without prior written
 *    permission of MetaStuff, Ltd. DOM4J is a registered
 *    trademark of MetaStuff, Ltd.
 *
 * 5. Due credit should be given to the DOM4J Project
 *    (http://dom4j.org/).
 *
 * THIS SOFTWARE IS PROVIDED BY METASTUFF, LTD. AND CONTRIBUTORS
 * ``AS IS'' AND ANY EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT
 * NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
 * FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL
 * METASTUFF, LTD. OR ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
 * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
 * OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * Copyright 2001 (C) MetaStuff, Ltd. All Rights Reserved.
 *
 * $Id: ElementStack.java,v 1.2 2003/06/10 16:18:34 per_nyfelt Exp $
 */