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   1  /*
   2  YUI 3.17.2 (build 9c3c78e)
   3  Copyright 2014 Yahoo! Inc. All rights reserved.
   4  Licensed under the BSD License.
   5  http://yuilibrary.com/license/
   6  */
   7  
   8  YUI.add('widget-parent', function (Y, NAME) {
   9  
  10  /**
  11   * Extension enabling a Widget to be a parent of another Widget.
  12   *
  13   * @module widget-parent
  14   */
  15  
  16  var Lang = Y.Lang,
  17      RENDERED = "rendered",
  18      BOUNDING_BOX = "boundingBox";
  19  
  20  /**
  21   * Widget extension providing functionality enabling a Widget to be a
  22   * parent of another Widget.
  23   *
  24   * <p>In addition to the set of attributes supported by WidgetParent, the constructor
  25   * configuration object can also contain a <code>children</code> which can be used
  26   * to add child widgets to the parent during construction. The <code>children</code>
  27   * property is an array of either child widget instances or child widget configuration
  28   * objects, and is sugar for the <a href="#method_add">add</a> method. See the
  29   * <a href="#method_add">add</a> for details on the structure of the child widget
  30   * configuration object.
  31   * @class WidgetParent
  32   * @constructor
  33   * @uses ArrayList
  34   * @param {Object} config User configuration object.
  35   */
  36  function Parent(config) {
  37  
  38      /**
  39      * Fires when a Widget is add as a child.  The event object will have a
  40      * 'child' property that returns a reference to the child Widget, as well
  41      * as an 'index' property that returns a reference to the index specified
  42      * when the add() method was called.
  43      * <p>
  44      * Subscribers to the "on" moment of this event, will be notified
  45      * before a child is added.
  46      * </p>
  47      * <p>
  48      * Subscribers to the "after" moment of this event, will be notified
  49      * after a child is added.
  50      * </p>
  51      *
  52      * @event addChild
  53      * @preventable _defAddChildFn
  54      * @param {EventFacade} e The Event Facade
  55      */
  56      this.publish("addChild", {
  57          defaultTargetOnly: true,
  58          defaultFn: this._defAddChildFn
  59      });
  60  
  61  
  62      /**
  63      * Fires when a child Widget is removed.  The event object will have a
  64      * 'child' property that returns a reference to the child Widget, as well
  65      * as an 'index' property that returns a reference child's ordinal position.
  66      * <p>
  67      * Subscribers to the "on" moment of this event, will be notified
  68      * before a child is removed.
  69      * </p>
  70      * <p>
  71      * Subscribers to the "after" moment of this event, will be notified
  72      * after a child is removed.
  73      * </p>
  74      *
  75      * @event removeChild
  76      * @preventable _defRemoveChildFn
  77      * @param {EventFacade} e The Event Facade
  78      */
  79      this.publish("removeChild", {
  80          defaultTargetOnly: true,
  81          defaultFn: this._defRemoveChildFn
  82      });
  83  
  84      this._items = [];
  85  
  86      var children,
  87          handle;
  88  
  89      if (config && config.children) {
  90  
  91          children = config.children;
  92  
  93          handle = this.after("initializedChange", function (e) {
  94              this._add(children);
  95              handle.detach();
  96          });
  97  
  98      }
  99  
 100      //  Widget method overlap
 101      Y.after(this._renderChildren, this, "renderUI");
 102      Y.after(this._bindUIParent, this, "bindUI");
 103  
 104      this.after("selectionChange", this._afterSelectionChange);
 105      this.after("selectedChange", this._afterParentSelectedChange);
 106      this.after("activeDescendantChange", this._afterActiveDescendantChange);
 107  
 108      this._hDestroyChild = this.after("*:destroy", this._afterDestroyChild);
 109      this.after("*:focusedChange", this._updateActiveDescendant);
 110  
 111  }
 112  
 113  Parent.ATTRS = {
 114  
 115      /**
 116       * @attribute defaultChildType
 117       * @type {String|Object}
 118       *
 119       * @description String representing the default type of the children
 120       * managed by this Widget.  Can also supply default type as a constructor
 121       * reference.
 122       */
 123      defaultChildType: {
 124          setter: function (val) {
 125  
 126              var returnVal = Y.Attribute.INVALID_VALUE,
 127                  FnConstructor = Lang.isString(val) ? Y[val] : val;
 128  
 129              if (Lang.isFunction(FnConstructor)) {
 130                  returnVal = FnConstructor;
 131              }
 132  
 133              return returnVal;
 134          }
 135      },
 136  
 137      /**
 138       * @attribute activeDescendant
 139       * @type Widget
 140       * @readOnly
 141       *
 142       * @description Returns the Widget's currently focused descendant Widget.
 143       */
 144      activeDescendant: {
 145          readOnly: true
 146      },
 147  
 148      /**
 149       * @attribute multiple
 150       * @type Boolean
 151       * @default false
 152       * @writeOnce
 153       *
 154       * @description Boolean indicating if multiple children can be selected at
 155       * once.  Whether or not multiple selection is enabled is always delegated
 156       * to the value of the <code>multiple</code> attribute of the root widget
 157       * in the object hierarchy.
 158       */
 159      multiple: {
 160          value: false,
 161          validator: Lang.isBoolean,
 162          writeOnce: true,
 163          getter: function (value) {
 164              var root = this.get("root");
 165              return (root && root != this) ? root.get("multiple") : value;
 166          }
 167      },
 168  
 169  
 170      /**
 171       * @attribute selection
 172       * @type {ArrayList|Widget}
 173       * @readOnly
 174       *
 175       * @description Returns the currently selected child Widget.  If the
 176       * <code>mulitple</code> attribte is set to <code>true</code> will
 177       * return an Y.ArrayList instance containing the currently selected
 178       * children.  If no children are selected, will return null.
 179       */
 180      selection: {
 181          readOnly: true,
 182          setter: "_setSelection",
 183          getter: function (value) {
 184              var selection = Lang.isArray(value) ?
 185                      (new Y.ArrayList(value)) : value;
 186              return selection;
 187          }
 188      },
 189  
 190      selected: {
 191          setter: function (value) {
 192  
 193              //  Enforces selection behavior on for parent Widgets.  Parent's
 194              //  selected attribute can be set to the following:
 195              //  0 - Not selected
 196              //  1 - Fully selected (all children are selected).  In order for
 197              //  all children to be selected, multiple selection must be
 198              //  enabled.  Therefore, you cannot set the "selected" attribute
 199              //  on a parent Widget to 1 unless multiple selection is enabled.
 200              //  2 - Partially selected, meaning one ore more (but not all)
 201              //  children are selected.
 202  
 203              var returnVal = value;
 204  
 205              if (value === 1 && !this.get("multiple")) {
 206                  Y.log('The selected attribute can only be set to 1 if the "multiple" attribute is set to true.', "error", "widget");
 207                  returnVal = Y.Attribute.INVALID_VALUE;
 208              }
 209  
 210              return returnVal;
 211          }
 212      }
 213  
 214  };
 215  
 216  Parent.prototype = {
 217  
 218      /**
 219       * The destructor implementation for Parent widgets. Destroys all children.
 220       * @method destructor
 221       */
 222      destructor: function() {
 223          this._destroyChildren();
 224      },
 225  
 226      /**
 227       * Destroy event listener for each child Widget, responsible for removing
 228       * the destroyed child Widget from the parent's internal array of children
 229       * (_items property).
 230       *
 231       * @method _afterDestroyChild
 232       * @protected
 233       * @param {EventFacade} event The event facade for the attribute change.
 234       */
 235      _afterDestroyChild: function (event) {
 236          var child = event.target;
 237  
 238          if (child.get("parent") == this) {
 239              child.remove();
 240          }
 241      },
 242  
 243      /**
 244       * Attribute change listener for the <code>selection</code>
 245       * attribute, responsible for setting the value of the
 246       * parent's <code>selected</code> attribute.
 247       *
 248       * @method _afterSelectionChange
 249       * @protected
 250       * @param {EventFacade} event The event facade for the attribute change.
 251       */
 252      _afterSelectionChange: function (event) {
 253  
 254          if (event.target == this && event.src != this) {
 255  
 256              var selection = event.newVal,
 257                  selectedVal = 0;    //  Not selected
 258  
 259  
 260              if (selection) {
 261  
 262                  selectedVal = 2;    //  Assume partially selected, confirm otherwise
 263  
 264  
 265                  if (Y.instanceOf(selection, Y.ArrayList) &&
 266                      (selection.size() === this.size())) {
 267  
 268                      selectedVal = 1;    //  Fully selected
 269  
 270                  }
 271  
 272              }
 273  
 274              this.set("selected", selectedVal, { src: this });
 275  
 276          }
 277      },
 278  
 279  
 280      /**
 281       * Attribute change listener for the <code>activeDescendant</code>
 282       * attribute, responsible for setting the value of the
 283       * parent's <code>activeDescendant</code> attribute.
 284       *
 285       * @method _afterActiveDescendantChange
 286       * @protected
 287       * @param {EventFacade} event The event facade for the attribute change.
 288       */
 289      _afterActiveDescendantChange: function (event) {
 290          var parent = this.get("parent");
 291  
 292          if (parent) {
 293              parent._set("activeDescendant", event.newVal);
 294          }
 295      },
 296  
 297      /**
 298       * Attribute change listener for the <code>selected</code>
 299       * attribute, responsible for syncing the selected state of all children to
 300       * match that of their parent Widget.
 301       *
 302       *
 303       * @method _afterParentSelectedChange
 304       * @protected
 305       * @param {EventFacade} event The event facade for the attribute change.
 306       */
 307      _afterParentSelectedChange: function (event) {
 308  
 309          var value = event.newVal;
 310  
 311          if (this == event.target && event.src != this &&
 312              (value === 0 || value === 1)) {
 313  
 314              this.each(function (child) {
 315  
 316                  //  Specify the source of this change as the parent so that
 317                  //  value of the parent's "selection" attribute isn't
 318                  //  recalculated
 319  
 320                  child.set("selected", value, { src: this });
 321  
 322              }, this);
 323  
 324          }
 325  
 326      },
 327  
 328  
 329      /**
 330       * Default setter for <code>selection</code> attribute changes.
 331       *
 332       * @method _setSelection
 333       * @protected
 334       * @param child {Widget|Array} Widget or Array of Widget instances.
 335       * @return {Widget|Array} Widget or Array of Widget instances.
 336       */
 337      _setSelection: function (child) {
 338  
 339          var selection = null,
 340              selected;
 341  
 342          if (this.get("multiple") && !this.isEmpty()) {
 343  
 344              selected = [];
 345  
 346              this.each(function (v) {
 347  
 348                 if (v.get("selected") > 0) {
 349                     selected.push(v);
 350                 }
 351  
 352              });
 353  
 354              if (selected.length > 0) {
 355                  selection = selected;
 356              }
 357  
 358          }
 359          else {
 360  
 361              if (child.get("selected") > 0) {
 362                  selection = child;
 363              }
 364  
 365          }
 366  
 367          return selection;
 368  
 369      },
 370  
 371  
 372      /**
 373       * Attribute change listener for the <code>selected</code>
 374       * attribute of child Widgets, responsible for setting the value of the
 375       * parent's <code>selection</code> attribute.
 376       *
 377       * @method _updateSelection
 378       * @protected
 379       * @param {EventFacade} event The event facade for the attribute change.
 380       */
 381      _updateSelection: function (event) {
 382  
 383          var child = event.target,
 384              selection;
 385  
 386          if (child.get("parent") == this) {
 387  
 388              if (event.src != "_updateSelection") {
 389  
 390                  selection = this.get("selection");
 391  
 392                  if (!this.get("multiple") && selection && event.newVal > 0) {
 393  
 394                      //  Deselect the previously selected child.
 395                      //  Set src equal to the current context to prevent
 396                      //  unnecessary re-calculation of the selection.
 397  
 398                      selection.set("selected", 0, { src: "_updateSelection" });
 399  
 400                  }
 401  
 402                  this._set("selection", child);
 403  
 404              }
 405  
 406              if (event.src == this) {
 407                  this._set("selection", child, { src: this });
 408              }
 409  
 410          }
 411  
 412      },
 413  
 414      /**
 415       * Attribute change listener for the <code>focused</code>
 416       * attribute of child Widgets, responsible for setting the value of the
 417       * parent's <code>activeDescendant</code> attribute.
 418       *
 419       * @method _updateActiveDescendant
 420       * @protected
 421       * @param {EventFacade} event The event facade for the attribute change.
 422       */
 423      _updateActiveDescendant: function (event) {
 424          var activeDescendant = (event.newVal === true) ? event.target : null;
 425          this._set("activeDescendant", activeDescendant);
 426      },
 427  
 428      /**
 429       * Creates an instance of a child Widget using the specified configuration.
 430       * By default Widget instances will be created of the type specified
 431       * by the <code>defaultChildType</code> attribute.  Types can be explicitly
 432       * defined via the <code>childType</code> property of the configuration object
 433       * literal. The use of the <code>type</code> property has been deprecated, but
 434       * will still be used as a fallback, if <code>childType</code> is not defined,
 435       * for backwards compatibility.
 436       *
 437       * @method _createChild
 438       * @protected
 439       * @param config {Object} Object literal representing the configuration
 440       * used to create an instance of a Widget.
 441       */
 442      _createChild: function (config) {
 443  
 444          var defaultType = this.get("defaultChildType"),
 445              altType = config.childType || config.type,
 446              child,
 447              Fn,
 448              FnConstructor;
 449  
 450          if (altType) {
 451              Fn = Lang.isString(altType) ? Y[altType] : altType;
 452          }
 453  
 454          if (Lang.isFunction(Fn)) {
 455              FnConstructor = Fn;
 456          } else if (defaultType) {
 457              // defaultType is normalized to a function in it's setter
 458              FnConstructor = defaultType;
 459          }
 460  
 461          if (FnConstructor) {
 462              child = new FnConstructor(config);
 463          } else {
 464              Y.error("Could not create a child instance because its constructor is either undefined or invalid.");
 465          }
 466  
 467          return child;
 468  
 469      },
 470  
 471      /**
 472       * Default addChild handler
 473       *
 474       * @method _defAddChildFn
 475       * @protected
 476       * @param event {EventFacade} The Event object
 477       * @param child {Widget} The Widget instance, or configuration
 478       * object for the Widget to be added as a child.
 479       * @param index {Number} Number representing the position at
 480       * which the child will be inserted.
 481       */
 482      _defAddChildFn: function (event) {
 483  
 484          var child = event.child,
 485              index = event.index,
 486              children = this._items;
 487  
 488          if (child.get("parent")) {
 489              child.remove();
 490          }
 491  
 492          if (Lang.isNumber(index)) {
 493              children.splice(index, 0, child);
 494          }
 495          else {
 496              children.push(child);
 497          }
 498  
 499          child._set("parent", this);
 500          child.addTarget(this);
 501  
 502          // Update index in case it got normalized after addition
 503          // (e.g. user passed in 10, and there are only 3 items, the actual index would be 3. We don't want to pass 10 around in the event facade).
 504          event.index = child.get("index");
 505  
 506          //  TO DO: Remove in favor of using event bubbling
 507          child.after("selectedChange", Y.bind(this._updateSelection, this));
 508      },
 509  
 510  
 511      /**
 512       * Default removeChild handler
 513       *
 514       * @method _defRemoveChildFn
 515       * @protected
 516       * @param event {EventFacade} The Event object
 517       * @param child {Widget} The Widget instance to be removed.
 518       * @param index {Number} Number representing the index of the Widget to
 519       * be removed.
 520       */
 521      _defRemoveChildFn: function (event) {
 522  
 523          var child = event.child,
 524              index = event.index,
 525              children = this._items;
 526  
 527          if (child.get("focused")) {
 528              child.blur(); // focused is readOnly, so use the public i/f to unset it
 529          }
 530  
 531          if (child.get("selected")) {
 532              child.set("selected", 0);
 533          }
 534  
 535          children.splice(index, 1);
 536  
 537          child.removeTarget(this);
 538          child._oldParent = child.get("parent");
 539          child._set("parent", null);
 540      },
 541  
 542      /**
 543      * @method _add
 544      * @protected
 545      * @param child {Widget|Object} The Widget instance, or configuration
 546      * object for the Widget to be added as a child.
 547      * @param child {Array} Array of Widget instances, or configuration
 548      * objects for the Widgets to be added as a children.
 549      * @param index {Number} (Optional.)  Number representing the position at
 550      * which the child should be inserted.
 551      * @description Adds a Widget as a child.  If the specified Widget already
 552      * has a parent it will be removed from its current parent before
 553      * being added as a child.
 554      * @return {Widget|Array} Successfully added Widget or Array containing the
 555      * successfully added Widget instance(s). If no children where added, will
 556      * will return undefined.
 557      */
 558      _add: function (child, index) {
 559  
 560          var children,
 561              oChild,
 562              returnVal;
 563  
 564  
 565          if (Lang.isArray(child)) {
 566  
 567              children = [];
 568  
 569              Y.each(child, function (v, k) {
 570  
 571                  oChild = this._add(v, (index + k));
 572  
 573                  if (oChild) {
 574                      children.push(oChild);
 575                  }
 576  
 577              }, this);
 578  
 579  
 580              if (children.length > 0) {
 581                  returnVal = children;
 582              }
 583  
 584          }
 585          else {
 586  
 587              if (Y.instanceOf(child, Y.Widget)) {
 588                  oChild = child;
 589              }
 590              else {
 591                  oChild = this._createChild(child);
 592              }
 593  
 594              if (oChild && this.fire("addChild", { child: oChild, index: index })) {
 595                  returnVal = oChild;
 596              }
 597  
 598          }
 599  
 600          return returnVal;
 601  
 602      },
 603  
 604  
 605      /**
 606      * @method add
 607      * @param child {Widget|Object} The Widget instance, or configuration
 608      * object for the Widget to be added as a child. The configuration object
 609      * for the child can include a <code>childType</code> property, which is either
 610      * a constructor function or a string which names a constructor function on the
 611      * Y instance (e.g. "Tab" would refer to Y.Tab) (<code>childType</code> used to be
 612      * named <code>type</code>, support for which has been deprecated, but is still
 613      * maintained for backward compatibility. <code>childType</code> takes precedence
 614      * over <code>type</code> if both are defined.
 615      * @param child {Array} Array of Widget instances, or configuration
 616      * objects for the Widgets to be added as a children.
 617      * @param index {Number} (Optional.)  Number representing the position at
 618      * which the child should be inserted.
 619      * @description Adds a Widget as a child.  If the specified Widget already
 620      * has a parent it will be removed from its current parent before
 621      * being added as a child.
 622      * @return {ArrayList} Y.ArrayList containing the successfully added
 623      * Widget instance(s).  If no children where added, will return an empty
 624      * Y.ArrayList instance.
 625      */
 626      add: function () {
 627  
 628          var added = this._add.apply(this, arguments),
 629              children = added ? (Lang.isArray(added) ? added : [added]) : [];
 630  
 631          return (new Y.ArrayList(children));
 632  
 633      },
 634  
 635  
 636      /**
 637      * @method remove
 638      * @param index {Number} (Optional.)  Number representing the index of the
 639      * child to be removed.
 640      * @description Removes the Widget from its parent.  Optionally, can remove
 641      * a child by specifying its index.
 642      * @return {Widget} Widget instance that was successfully removed, otherwise
 643      * undefined.
 644      */
 645      remove: function (index) {
 646  
 647          var child = this._items[index],
 648              returnVal;
 649  
 650          if (child && this.fire("removeChild", { child: child, index: index })) {
 651              returnVal = child;
 652          }
 653  
 654          return returnVal;
 655  
 656      },
 657  
 658  
 659      /**
 660      * @method removeAll
 661      * @description Removes all of the children from the Widget.
 662      * @return {ArrayList} Y.ArrayList instance containing Widgets that were
 663      * successfully removed.  If no children where removed, will return an empty
 664      * Y.ArrayList instance.
 665      */
 666      removeAll: function () {
 667  
 668          var removed = [],
 669              child;
 670  
 671          Y.each(this._items.concat(), function () {
 672  
 673              child = this.remove(0);
 674  
 675              if (child) {
 676                  removed.push(child);
 677              }
 678  
 679          }, this);
 680  
 681          return (new Y.ArrayList(removed));
 682  
 683      },
 684  
 685      /**
 686       * Selects the child at the given index (zero-based).
 687       *
 688       * @method selectChild
 689       * @param {Number} i the index of the child to be selected
 690       */
 691      selectChild: function(i) {
 692          this.item(i).set('selected', 1);
 693      },
 694  
 695      /**
 696       * Selects all children.
 697       *
 698       * @method selectAll
 699       */
 700      selectAll: function () {
 701          this.set("selected", 1);
 702      },
 703  
 704      /**
 705       * Deselects all children.
 706       *
 707       * @method deselectAll
 708       */
 709      deselectAll: function () {
 710          this.set("selected", 0);
 711      },
 712  
 713      /**
 714       * Updates the UI in response to a child being added.
 715       *
 716       * @method _uiAddChild
 717       * @protected
 718       * @param child {Widget} The child Widget instance to render.
 719       * @param parentNode {Object} The Node under which the
 720       * child Widget is to be rendered.
 721       */
 722      _uiAddChild: function (child, parentNode) {
 723  
 724          child.render(parentNode);
 725  
 726          // TODO: Ideally this should be in Child's render UI.
 727  
 728          var childBB = child.get("boundingBox"),
 729              siblingBB,
 730              nextSibling = child.next(false),
 731              prevSibling;
 732  
 733          // Insert or Append to last child.
 734  
 735          // Avoiding index, and using the current sibling
 736          // state (which should be accurate), means we don't have
 737          // to worry about decorator elements which may be added
 738          // to the _childContainer node.
 739  
 740          if (nextSibling && nextSibling.get(RENDERED)) {
 741  
 742              siblingBB = nextSibling.get(BOUNDING_BOX);
 743              siblingBB.insert(childBB, "before");
 744  
 745          } else {
 746  
 747              prevSibling = child.previous(false);
 748  
 749              if (prevSibling && prevSibling.get(RENDERED)) {
 750  
 751                  siblingBB = prevSibling.get(BOUNDING_BOX);
 752                  siblingBB.insert(childBB, "after");
 753  
 754              } else if (!parentNode.contains(childBB)) {
 755  
 756                  // Based on pull request from andreas-karlsson
 757                  // https://github.com/yui/yui3/pull/25#issuecomment-2103536
 758  
 759                  // Account for case where a child was rendered independently of the
 760                  // parent-child framework, to a node outside of the parentNode,
 761                  // and there are no siblings.
 762  
 763                  parentNode.appendChild(childBB);
 764              }
 765          }
 766  
 767      },
 768  
 769      /**
 770       * Updates the UI in response to a child being removed.
 771       *
 772       * @method _uiRemoveChild
 773       * @protected
 774       * @param child {Widget} The child Widget instance to render.
 775       */
 776      _uiRemoveChild: function (child) {
 777          child.get("boundingBox").remove();
 778      },
 779  
 780      _afterAddChild: function (event) {
 781          var child = event.child;
 782  
 783          if (child.get("parent") == this) {
 784              this._uiAddChild(child, this._childrenContainer);
 785          }
 786      },
 787  
 788      _afterRemoveChild: function (event) {
 789          var child = event.child;
 790  
 791          if (child._oldParent == this) {
 792              this._uiRemoveChild(child);
 793          }
 794      },
 795  
 796      /**
 797       * Sets up DOM and CustomEvent listeners for the parent widget.
 798       * <p>
 799       * This method in invoked after bindUI is invoked for the Widget class
 800       * using YUI's aop infrastructure.
 801       * </p>
 802       *
 803       * @method _bindUIParent
 804       * @protected
 805       */
 806      _bindUIParent: function () {
 807          this.after("addChild", this._afterAddChild);
 808          this.after("removeChild", this._afterRemoveChild);
 809      },
 810  
 811      /**
 812       * Renders all child Widgets for the parent.
 813       * <p>
 814       * This method in invoked after renderUI is invoked for the Widget class
 815       * using YUI's aop infrastructure.
 816       * </p>
 817       * @method _renderChildren
 818       * @protected
 819       */
 820      _renderChildren: function () {
 821  
 822          /**
 823           * <p>By default WidgetParent will render it's children to the parent's content box.</p>
 824           *
 825           * <p>If the children need to be rendered somewhere else, the _childrenContainer property
 826           * can be set to the Node which the children should be rendered to. This property should be
 827           * set before the _renderChildren method is invoked, ideally in your renderUI method,
 828           * as soon as you create the element to be rendered to.</p>
 829           *
 830           * @protected
 831           * @property _childrenContainer
 832           * @value The content box
 833           * @type Node
 834           */
 835          var renderTo = this._childrenContainer || this.get("contentBox");
 836  
 837          this._childrenContainer = renderTo;
 838  
 839          this.each(function (child) {
 840              child.render(renderTo);
 841          });
 842      },
 843  
 844      /**
 845       * Destroys all child Widgets for the parent.
 846       * <p>
 847       * This method is invoked before the destructor is invoked for the Widget
 848       * class using YUI's aop infrastructure.
 849       * </p>
 850       * @method _destroyChildren
 851       * @protected
 852       */
 853      _destroyChildren: function () {
 854  
 855          //  Detach the handler responsible for removing children in
 856          //  response to destroying them since:
 857          //  1)  It is unnecessary/inefficient at this point since we are doing
 858          //      a batch destroy of all children.
 859          //  2)  Removing each child will affect our ability to iterate the
 860          //      children since the size of _items will be changing as we
 861          //      iterate.
 862          this._hDestroyChild.detach();
 863  
 864          //  Need to clone the _items array since
 865          this.each(function (child) {
 866              child.destroy();
 867          });
 868      }
 869  
 870  };
 871  
 872  Y.augment(Parent, Y.ArrayList);
 873  
 874  Y.WidgetParent = Parent;
 875  
 876  
 877  }, '3.17.2', {"requires": ["arraylist", "base-build", "widget"]});