content: /*
   * Copyright (c) 2009 World Wide Web Consortium,
   *
   * (Massachusetts Institute of Technology, European Research Consortium for
   * Informatics and Mathematics, Keio University). All Rights Reserved. This
   * work is distributed under the W3C(r) Software License [1] in the hope that
   * it will be useful, but WITHOUT ANY WARRANTY; without even the implied
   * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
   *
   * [1] http://www.w3.org/Consortium/Legal/2002/copyright-software-20021231
   */
  
  package mf.org.w3c.dom;
  
  /**
   * The <code>ElementTraversal</code> interface is a set of read-only attributes
   * which allow an author to easily navigate between elements in a document.
   * <p>In conforming implementations of Element Traversal, all objects that
   * implement {@link Element} must also implement the
   * <code>ElementTraversal</code> interface. Four of the methods,
   * {@link #getFirstElementChild}, {@link #getLastElementChild},
   * {@link #getPreviousElementSibling}, and {@link #getNextElementSibling},
   * each return a live reference to another element with the defined
   * relationship to the current element, if the related element exists. The
   * fifth method, {@link #getChildElementCount}, exposes the number of child
   * elements of an element, for preprocessing before navigation.
   * <p>See also the
   * <a href='http://www.w3.org/TR/ElementTraversal/'><cite>Element Traversal Specification</cite></a>.
   */
  public interface ElementTraversal {
  
      /**
       * Returns the first child element node of this element. <code>null</code>
       * if this element has no child elements.
       */
      Element getFirstElementChild();
  
      /**
       * Returns the last child element node of this element. <code>null</code>
       * if this element has no child elements.
       */
      Element getLastElementChild();
  
      /**
       * Returns the previous sibling element node of this element.
       * <code>null</code> if this element has no element sibling nodes that
       * come before this one in the document tree.
       */
      Element getPreviousElementSibling();
  
      /**
       * Returns the next sibling element node of this element.
       * <code>null</code> if this element has no element sibling nodes that
       * come after this one in the document tree.
       */
      Element getNextElementSibling();
  
      /**
       * Returns the current number of element nodes that are children of this
       * element. <code>0</code> if this element has no child nodes that are of
       * <code>nodeType</code> <code>1</code>.
       */
      int getChildElementCount();
  }
  