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/*
* 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 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();
}