// Copyright 2008 The Closure Library Authors. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//      http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS-IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

/**
 * @fileoverview Iterator subclass for DOM tree traversal.
 *
 * @author robbyw@google.com (Robby Walker)
 */

goog.provide('goog.dom.NodeIterator');

goog.require('goog.dom.TagIterator');



/**
 * A DOM tree traversal iterator.
 *
 * Starting with the given node, the iterator walks the DOM in order, reporting
 * events for each node.  The iterator acts as a prefix iterator:
 *
 * <pre>
 * &lt;div&gt;1&lt;span&gt;2&lt;/span&gt;3&lt;/div&gt;
 * </pre>
 *
 * Will return the following nodes:
 *
 * <code>[div, 1, span, 2, 3]</code>
 *
 * With the following depths
 *
 * <code>[1, 1, 2, 2, 1]</code>
 *
 * Imagining <code>|</code> represents iterator position, the traversal stops at
 * each of the following locations:
 *
 * <pre>&lt;div&gt;|1|&lt;span&gt;|2|&lt;/span&gt;3|&lt;/div&gt;</pre>
 *
 * The iterator can also be used in reverse mode, which will return the nodes
 * and states in the opposite order.  The depths will be slightly different
 * since, like in normal mode, the depth is computed *after* the last move.
 *
 * Lastly, it is possible to create an iterator that is unconstrained, meaning
 * that it will continue iterating until the end of the document instead of
 * until exiting the start node.
 *
 * @param {Node=} opt_node The start node.  Defaults to an empty iterator.
 * @param {boolean=} opt_reversed Whether to traverse the tree in reverse.
 * @param {boolean=} opt_unconstrained Whether the iterator is not constrained
 *     to the starting node and its children.
 * @param {number=} opt_depth The starting tree depth.
 * @constructor
 * @extends {goog.dom.TagIterator}
 * @final
 */
goog.dom.NodeIterator = function(
    opt_node, opt_reversed, opt_unconstrained, opt_depth) {
  goog.dom.TagIterator.call(
      this, opt_node, opt_reversed, opt_unconstrained, null, opt_depth);
};
goog.inherits(goog.dom.NodeIterator, goog.dom.TagIterator);


/**
 * Moves to the next position in the DOM tree.
 * @return {Node} Returns the next node, or throws a goog.iter.StopIteration
 *     exception if the end of the iterator's range has been reached.
 * @override
 */
goog.dom.NodeIterator.prototype.next = function() {
  do {
    goog.dom.NodeIterator.superClass_.next.call(this);
  } while (this.isEndTag());

  return this.node;
};