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// Copyright 2018 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
/**
* @fileoverview |ListPropertyUpdateBehavior| is used to update an existing
* polymer list property given the list after all the edits were made while
* maintaining the reference to the original list. This allows
* dom-repeat/iron-list elements bound to this list property to not fully
* re-rendered from scratch.
*
* The minimal splices needed to transform the original list to the edited list
* are calculated using |Polymer.ArraySplice.calculateSplices|. All the edits
* are then applied to the original list. Once completed, a single notification
* containing information about all the edits is sent to the polyer object.
*/
/** @polymerBehavior */
const ListPropertyUpdateBehavior = {
/**
* @param {string} propertyName
* @param {function(!Object): string} itemUidGetter
* @param {!Array<!Object>} updatedList
*/
updateList: function(propertyName, itemUidGetter, updatedList) {
const list = this[propertyName];
const splices = Polymer.ArraySplice.calculateSplices(
updatedList.map(itemUidGetter), list.map(itemUidGetter));
splices.forEach(splice => {
const index = splice.index;
const deleteCount = splice.removed.length;
// Transform splices to the expected format of notifySplices().
// Convert !Array<string> to !Array<!Object>.
splice.removed = list.slice(index, index + deleteCount);
splice.object = list;
splice.type = 'splice';
const added = updatedList.slice(index, index + splice.addedCount);
const spliceParams = [index, deleteCount].concat(added);
list.splice.apply(list, spliceParams);
});
if (splices.length > 0) {
this.notifySplices(propertyName, splices);
}
},
};
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