DataDiffer.js
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/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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.
*/
function defaultKeyGetter(item) {
return item;
}
/**
* @param {Array} oldArr
* @param {Array} newArr
* @param {Function} oldKeyGetter
* @param {Function} newKeyGetter
* @param {Object} [context] Can be visited by this.context in callback.
*/
function DataDiffer(oldArr, newArr, oldKeyGetter, newKeyGetter, context) {
this._old = oldArr;
this._new = newArr;
this._oldKeyGetter = oldKeyGetter || defaultKeyGetter;
this._newKeyGetter = newKeyGetter || defaultKeyGetter;
this.context = context;
}
DataDiffer.prototype = {
constructor: DataDiffer,
/**
* Callback function when add a data
*/
add: function (func) {
this._add = func;
return this;
},
/**
* Callback function when update a data
*/
update: function (func) {
this._update = func;
return this;
},
/**
* Callback function when remove a data
*/
remove: function (func) {
this._remove = func;
return this;
},
execute: function () {
var oldArr = this._old;
var newArr = this._new;
var oldDataIndexMap = {};
var newDataIndexMap = {};
var oldDataKeyArr = [];
var newDataKeyArr = [];
var i;
initIndexMap(oldArr, oldDataIndexMap, oldDataKeyArr, '_oldKeyGetter', this);
initIndexMap(newArr, newDataIndexMap, newDataKeyArr, '_newKeyGetter', this);
// Travel by inverted order to make sure order consistency
// when duplicate keys exists (consider newDataIndex.pop() below).
// For performance consideration, these code below do not look neat.
for (i = 0; i < oldArr.length; i++) {
var key = oldDataKeyArr[i];
var idx = newDataIndexMap[key];
// idx can never be empty array here. see 'set null' logic below.
if (idx != null) {
// Consider there is duplicate key (for example, use dataItem.name as key).
// We should make sure every item in newArr and oldArr can be visited.
var len = idx.length;
if (len) {
len === 1 && (newDataIndexMap[key] = null);
idx = idx.unshift();
}
else {
newDataIndexMap[key] = null;
}
this._update && this._update(idx, i);
}
else {
this._remove && this._remove(i);
}
}
for (var i = 0; i < newDataKeyArr.length; i++) {
var key = newDataKeyArr[i];
if (newDataIndexMap.hasOwnProperty(key)) {
var idx = newDataIndexMap[key];
if (idx == null) {
continue;
}
// idx can never be empty array here. see 'set null' logic above.
if (!idx.length) {
this._add && this._add(idx);
}
else {
for (var j = 0, len = idx.length; j < len; j++) {
this._add && this._add(idx[j]);
}
}
}
}
}
};
function initIndexMap(arr, map, keyArr, keyGetterName, dataDiffer) {
for (var i = 0; i < arr.length; i++) {
// Add prefix to avoid conflict with Object.prototype.
var key = '_ec_' + dataDiffer[keyGetterName](arr[i], i);
var existence = map[key];
if (existence == null) {
keyArr.push(key);
map[key] = i;
}
else {
if (!existence.length) {
map[key] = existence = [existence];
}
existence.push(i);
}
}
}
export default DataDiffer;