| /* | 
 |  * Copyright (C) 2017, 2018 Apple Inc. All rights reserved. | 
 |  * | 
 |  * Redistribution and use in source and binary forms, with or without | 
 |  * modification, are permitted provided that the following conditions | 
 |  * are met: | 
 |  * 1. Redistributions of source code must retain the above copyright | 
 |  *    notice, this list of conditions and the following disclaimer. | 
 |  * 2. Redistributions in binary form must reproduce the above copyright | 
 |  *    notice, this list of conditions and the following disclaimer in the | 
 |  *    documentation and/or other materials provided with the distribution. | 
 |  * | 
 |  * THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS'' | 
 |  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, | 
 |  * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR | 
 |  * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS | 
 |  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR | 
 |  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF | 
 |  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS | 
 |  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN | 
 |  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) | 
 |  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF | 
 |  * THE POSSIBILITY OF SUCH DAMAGE. | 
 |  */ | 
 |  | 
 | WI.TreeOutlineGroup = class TreeOutlineGroup extends WI.Collection | 
 | { | 
 |     // Public | 
 |  | 
 |     objectIsRequiredType(object) | 
 |     { | 
 |         return object instanceof WI.TreeOutline; | 
 |     } | 
 |  | 
 |     get selectedTreeElement() | 
 |     { | 
 |         for (let treeOutline of this) { | 
 |             if (treeOutline.selectedTreeElement) | 
 |                 return treeOutline.selectedTreeElement; | 
 |         } | 
 |  | 
 |         return null; | 
 |     } | 
 |  | 
 |     // Protected | 
 |  | 
 |     itemAdded(treeOutline) | 
 |     { | 
 |         if (treeOutline.selectedTreeElement) | 
 |             this._removeConflictingTreeSelections(treeOutline); | 
 |  | 
 |         treeOutline.addEventListener(WI.TreeOutline.Event.SelectionDidChange, this._treeOutlineSelectionDidChange, this); | 
 |     } | 
 |  | 
 |     itemRemoved(treeOutline) | 
 |     { | 
 |         treeOutline.removeEventListener(WI.TreeOutline.Event.SelectionDidChange, this._treeOutlineSelectionDidChange, this); | 
 |     } | 
 |  | 
 |     // Private | 
 |  | 
 |     _removeConflictingTreeSelections(selectedTreeOutline) | 
 |     { | 
 |         for (let treeOutline of this) { | 
 |             if (selectedTreeOutline === treeOutline) | 
 |                 continue; | 
 |  | 
 |             treeOutline.selectedTreeElement = null; | 
 |         } | 
 |     } | 
 |  | 
 |     _treeOutlineSelectionDidChange(event) | 
 |     { | 
 |         let treeOutline = event.target; | 
 |         if (!treeOutline.selectedTreeElement) | 
 |             return; | 
 |  | 
 |         this._removeConflictingTreeSelections(treeOutline); | 
 |     } | 
 | }; |