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work on sorted list from map
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30
src/observable/BaseObservableCollection.js
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30
src/observable/BaseObservableCollection.js
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@ -0,0 +1,30 @@
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export default class BaseObservableCollection {
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constructor() {
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this._handlers = new Set();
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}
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onSubscribeFirst() {
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}
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onUnsubscribeLast() {
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}
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subscribe(handler) {
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this._handlers.add(handler);
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if (this._handlers.length === 1) {
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this.onSubscribeFirst();
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}
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return () => {
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if (handler) {
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this._handlers.delete(this._handler);
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if (this._handlers.length === 0) {
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this.onUnsubscribeLast();
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}
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handler = null;
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}
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return null;
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};
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}
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}
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37
src/observable/list/BaseObservableList.js
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37
src/observable/list/BaseObservableList.js
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import BaseObservableCollection from "../BaseObservableCollection.js";
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export default class BaseObservableList extends BaseObservableCollection {
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emitReset() {
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for(let h of this._handlers) {
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h.onReset();
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}
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}
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// we need batch events, mostly on index based collection though?
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// maybe we should get started without?
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emitAdd(index, value) {
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for(let h of this._handlers) {
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h.onAdd(index, value);
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}
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}
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emitChange(index, value, params) {
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for(let h of this._handlers) {
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h.onChange(index, value, params);
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}
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}
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emitRemove(index, value) {
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for(let h of this._handlers) {
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h.onRemove(index, value);
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}
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}
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// toIdx assumes the item has already
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// been removed from its fromIdx
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emitMove(fromIdx, toIdx, value) {
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for(let h of this._handlers) {
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h.onMove(fromIdx, toIdx, value);
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}
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}
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}
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@ -1,4 +1,30 @@
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import Operator from "../Operator.js";
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import BaseObservableList from "../BaseObservableList.js";
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/*
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when a value changes, it sorting order can change. It would still be at the old index prior to firing an onChange event.
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So how do you know where it was before it changed, if not by going over all values?
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how to make this fast?
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seems hard to solve with an array, because you need to map the key to it's previous location somehow, to efficiently find it,
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and move it.
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I wonder if we could do better with a binary search tree (BST).
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The tree has a value with {key, value}. There is a plain Map mapping keys to this tuple,
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for easy lookup. Now how do we find the index of this tuple in the BST?
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either we store in every node the amount of nodes on the left and right, or we decend into the part
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of the tree preceding the node we want to know about. Updating the counts upwards would probably be fine as this is log2 of
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the size of the container.
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to be able to go from a key to an index, the value would have the have a link with the tree node though
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so key -> Map<key,value> -> value -> node -> *parentNode -> rootNode
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with a node containing {value, leftCount, rightCount, leftNode, rightNode, parentNode}
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*/
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/**
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* @license
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@ -26,44 +52,54 @@ function sortedIndex(array, value, comparator) {
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}
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return high;
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}
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// TODO: this should not inherit from an BaseObservableMap, as it's a list
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export default class SortOperator extends Operator {
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constructor(sourceMap, comparator) {
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super(sourceMap);
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// no duplicates allowed for now
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export default class SortOperator extends BaseObservableList {
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constructor(sourceMap, comparator, getKey) {
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super();
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this._sourceMap = sourceMap;
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this._comparator = comparator;
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this._getKey = getKey;
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this._sortedValues = [];
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this._keyIndex = new Map();
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}
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onAdd(key, value) {
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const idx = sortedIndex(this._sortedValues, value, this._comparator);
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this._sortedValues.splice(idx, 0, value);
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this._keyIndex.set(key, idx);
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this.emitAdd(idx, value);
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}
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onRemove(key, _value) {
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onRemove(key, value) {
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const idx = sortedIndex(this._sortedValues, value, this._comparator);
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this._sortedValues.splice(idx, 0, value);
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this._keyIndex.set(key, idx);
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this.emitAdd(idx, value);
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this._sortedValues.splice(idx, 1);
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this.emitRemove(idx, value);
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}
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onChange(key, value, params) {
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// index could have moved if other items got added in the meantime
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const oldIdx = this._keyIndex.get(key);
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const idxIfSortUnchanged = sortedIndex(this._sortedValues, value, this._comparator);
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if (this._getKey(this._sortedValues[idxIfSortUnchanged]) === key) {
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this.emitChange(idxIfSortUnchanged, value, params);
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} else {
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// TODO: slow!? See above for idea with BST to speed this up if we need to
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const oldIdx = this._sortedValues.find(v => this._getKey(v) === key);
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this._sortedValues.splice(oldIdx, 1);
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const idx = sortedIndex(this._sortedValues, value, this._comparator);
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const newIdx = sortedIndex(this._sortedValues, value, this._comparator);
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this._sortedValues.splice(newIdx, 0, value);
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this.emitMove(oldIdx, newIdx, value);
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this.emitChange(newIdx, value, params);
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}
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}
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onReset() {
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this._sortedValues = [];
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this.emitReset();
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}
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onSubscribeFirst() {
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this._sortedValues = new Array(this._source.size);
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this._mapSubscription = this._sourceMap.subscribe(this);
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this._sortedValues = new Array(this._sourceMap.size);
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let i = 0;
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for (let [key, value] of this._source) {
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for (let [, value] of this._sourceMap) {
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this._sortedValues[i] = value;
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this._keyIndex.set(key, i);
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++i;
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}
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this._sortedValues.sort(this._comparator);
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@ -73,15 +109,12 @@ export default class SortOperator extends Operator {
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onUnsubscribeLast() {
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super.onUnsubscribeLast();
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this._sortedValues = null;
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this._mapSubscription = this._mapSubscription();
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}
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onReset() {
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this._sortedValues = [];
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this.emitReset();
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}
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get length() {
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return this._source.size;
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return this._sourceMap.size;
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}
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[Symbol.iterator]() {
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@ -1,11 +1,8 @@
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import MapOperator from "./operators/MapOperator.js";
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import SortOperator from "./operators/SortOperator.js";
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import BaseObservableCollection from "../BaseObservableCollection.js";
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export default class BaseObservableMap {
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constructor() {
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this._handlers = new Set();
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}
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export default class BaseObservableMap extends BaseObservableCollection {
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emitReset() {
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for(let h of this._handlers) {
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h.onReset();
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@ -31,31 +28,6 @@ export default class BaseObservableMap {
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}
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}
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onSubscribeFirst() {
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}
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onUnsubscribeLast() {
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}
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subscribe(handler) {
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this._handlers.add(handler);
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if (this._handlers.length === 1) {
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this.onSubscribeFirst();
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}
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return () => {
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if (handler) {
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this._handlers.delete(this._handler);
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if (this._handlers.length === 0) {
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this.onUnsubscribeLast();
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}
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handler = null;
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}
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return null;
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};
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}
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map(mapper, updater) {
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return new MapOperator(this, mapper, updater);
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}
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