8135283: DOM API update: Element Traversal Specification

Reviewed-by: mchung, lancea

jaxp/src/java.xml/share/classes/org/w3c/dom/ElementTraversal.java

@@ -0,0 +1,103 @@
+/*
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.  Oracle designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Oracle in the LICENSE file that accompanied this code.
+ *
+ * This code is distributed 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.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+/*
+ * Copyright (c) 2015 World Wide Web Consortium,
+ *
+ * (Massachusetts Institute of Technology, European Research Consortium for
+ * Informatics and Mathematics, Keio University, Beihang). 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/copyright-software
+ */
+
+package org.w3c.dom;
+
+/**
+ * The {@code ElementTraversal} 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}
+ * interface. Four of the methods,
+ * {@link #getFirstElementChild}, {@link #getLastElementChild},
+ * {@link #getPreviousElementSibling}, and {@link #getNextElementSibling},
+ * each provides 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.
+ *
+ * @see
+ * <a href='http://www.w3.org/TR/ElementTraversal/'><cite>Element Traversal Specification</cite></a>.
+ *
+ * @since 9
+ */
+public interface ElementTraversal {
+
+    /**
+     * Returns a reference to the first child node of the element which is of
+     * the {@link Element} type.
+     *
+     * @return a reference to an element child, {@code null} if the element has
+     * no child of the {@link Element} type.
+     */
+    Element getFirstElementChild();
+
+    /**
+     * Returns a reference to the last child node of the element which is of
+     * the {@link Element} type.
+     *
+     * @return a reference to an element child, {@code null} if the element has
+     * no child of the {@link Element} type.
+     */
+    Element getLastElementChild();
+
+    /**
+     * Returns a reference to the sibling node of the element which most immediately
+     * precedes the element in document order, and which is of the {@link Element} type.
+     *
+     * @return a reference to an element child, {@code null} if the element has
+     * no sibling node of the {@link Element} type that comes before this one.
+     */
+    Element getPreviousElementSibling();
+
+    /**
+     * Returns a reference to the sibling node of the element which most immediately
+     * follows the element in document order, and which is of the {@link Element} type.
+     *
+     * @return a reference to an element child, {@code null} if the element has
+     * no sibling node of the {@link Element} type that comes after this one.
+     */
+    Element getNextElementSibling();
+
+    /**
+     * Returns the current number of child nodes of the element which are of
+     * the {@link Element} type.
+     *
+     * @return the number of element children, or {@code 0} if the element has
+     * no element children.
+     */
+    int getChildElementCount();
+}