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      1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style license that can be
      3 // found in the LICENSE file.
      4 
      5 base.exportTo('ui', function() {
      6 
      7   /**
      8    * Helper function for creating new element for define.
      9    */
     10   function createElementHelper(tagName, opt_bag) {
     11     // Allow passing in ownerDocument to create in a different document.
     12     var doc;
     13     if (opt_bag && opt_bag.ownerDocument)
     14       doc = opt_bag.ownerDocument;
     15 
     16     return doc.createElement(tagName);
     17   }
     18 
     19   /**
     20    * Creates the constructor for a UI element class.
     21    *
     22    * Usage:
     23    * <pre>
     24    * var List = base.ui.define('list');
     25    * List.prototype = {
     26    *   __proto__: HTMLUListElement.prototype,
     27    *   decorate: function() {
     28    *     ...
     29    *   },
     30    *   ...
     31    * };
     32    * </pre>
     33    *
     34    * @param {string|Function} tagNameOrFunction The tagName or
     35    *     function to use for newly created elements. If this is a function it
     36    *     needs to return a new element when called.
     37    * @return {function(Object=):Element} The constructor function which takes
     38    *     an optional property bag. The function also has a static
     39    *     {@code decorate} method added to it.
     40    */
     41   function define(tagNameOrFunction) {
     42     var createFunction, tagName;
     43     if (typeof tagNameOrFunction == 'function') {
     44       createFunction = tagNameOrFunction;
     45       tagName = '';
     46     } else {
     47       createFunction = createElementHelper;
     48       tagName = tagNameOrFunction;
     49     }
     50 
     51     /**
     52      * Creates a new UI element constructor.
     53      * @param {Object=} opt_propertyBag Optional bag of properties to set on the
     54      *     object after created. The property {@code ownerDocument} is special
     55      *     cased and it allows you to create the element in a different
     56      *     document than the default.
     57      * @constructor
     58      */
     59     function f(opt_propertyBag) {
     60       var el = createFunction(tagName, opt_propertyBag);
     61       f.decorate(el);
     62       for (var propertyName in opt_propertyBag) {
     63         el[propertyName] = opt_propertyBag[propertyName];
     64       }
     65       return el;
     66     }
     67 
     68     /**
     69      * Decorates an element as a UI element class.
     70      * @param {!Element} el The element to decorate.
     71      */
     72     f.decorate = function(el) {
     73       el.__proto__ = f.prototype;
     74       el.decorate();
     75     };
     76 
     77     return f;
     78   }
     79 
     80   return {
     81     define: define
     82   };
     83 });
     84