es6/operators/groupBy.js
import { Subscriber } from '../Subscriber';
import { Subscription } from '../Subscription';
import { Observable } from '../Observable';
import { Subject } from '../Subject';
import { Map } from '../util/Map';
import { FastMap } from '../util/FastMap';
/* tslint:enable:max-line-length */
/**
* Groups the items emitted by an Observable according to a specified criterion,
* and emits these grouped items as `GroupedObservables`, one
* {@link GroupedObservable} per group.
*
* <img src="./img/groupBy.png" width="100%">
*
* @example <caption>Group objects by id and return as array</caption>
* Observable.of<Obj>({id: 1, name: 'aze1'},
* {id: 2, name: 'sf2'},
* {id: 2, name: 'dg2'},
* {id: 1, name: 'erg1'},
* {id: 1, name: 'df1'},
* {id: 2, name: 'sfqfb2'},
* {id: 3, name: 'qfs3'},
* {id: 2, name: 'qsgqsfg2'}
* )
* .groupBy(p => p.id)
* .flatMap( (group$) => group$.reduce((acc, cur) => [...acc, cur], []))
* .subscribe(p => console.log(p));
*
* // displays:
* // [ { id: 1, name: 'aze1' },
* // { id: 1, name: 'erg1' },
* // { id: 1, name: 'df1' } ]
* //
* // [ { id: 2, name: 'sf2' },
* // { id: 2, name: 'dg2' },
* // { id: 2, name: 'sfqfb2' },
* // { id: 2, name: 'qsgqsfg2' } ]
* //
* // [ { id: 3, name: 'qfs3' } ]
*
* @example <caption>Pivot data on the id field</caption>
* Observable.of<Obj>({id: 1, name: 'aze1'},
* {id: 2, name: 'sf2'},
* {id: 2, name: 'dg2'},
* {id: 1, name: 'erg1'},
* {id: 1, name: 'df1'},
* {id: 2, name: 'sfqfb2'},
* {id: 3, name: 'qfs1'},
* {id: 2, name: 'qsgqsfg2'}
* )
* .groupBy(p => p.id, p => p.name)
* .flatMap( (group$) => group$.reduce((acc, cur) => [...acc, cur], ["" + group$.key]))
* .map(arr => ({'id': parseInt(arr[0]), 'values': arr.slice(1)}))
* .subscribe(p => console.log(p));
*
* // displays:
* // { id: 1, values: [ 'aze1', 'erg1', 'df1' ] }
* // { id: 2, values: [ 'sf2', 'dg2', 'sfqfb2', 'qsgqsfg2' ] }
* // { id: 3, values: [ 'qfs1' ] }
*
* @param {function(value: T): K} keySelector A function that extracts the key
* for each item.
* @param {function(value: T): R} [elementSelector] A function that extracts the
* return element for each item.
* @param {function(grouped: GroupedObservable<K,R>): Observable<any>} [durationSelector]
* A function that returns an Observable to determine how long each group should
* exist.
* @return {Observable<GroupedObservable<K,R>>} An Observable that emits
* GroupedObservables, each of which corresponds to a unique key value and each
* of which emits those items from the source Observable that share that key
* value.
* @method groupBy
* @owner Observable
*/
export function groupBy(keySelector, elementSelector, durationSelector, subjectSelector) {
return (source) => source.lift(new GroupByOperator(keySelector, elementSelector, durationSelector, subjectSelector));
}
class GroupByOperator {
constructor(keySelector, elementSelector, durationSelector, subjectSelector) {
this.keySelector = keySelector;
this.elementSelector = elementSelector;
this.durationSelector = durationSelector;
this.subjectSelector = subjectSelector;
}
call(subscriber, source) {
return source.subscribe(new GroupBySubscriber(subscriber, this.keySelector, this.elementSelector, this.durationSelector, this.subjectSelector));
}
}
/**
* We need this JSDoc comment for affecting ESDoc.
* @ignore
* @extends {Ignored}
*/
class GroupBySubscriber extends Subscriber {
constructor(destination, keySelector, elementSelector, durationSelector, subjectSelector) {
super(destination);
this.keySelector = keySelector;
this.elementSelector = elementSelector;
this.durationSelector = durationSelector;
this.subjectSelector = subjectSelector;
this.groups = null;
this.attemptedToUnsubscribe = false;
this.count = 0;
}
_next(value) {
let key;
try {
key = this.keySelector(value);
}
catch (err) {
this.error(err);
return;
}
this._group(value, key);
}
_group(value, key) {
let groups = this.groups;
if (!groups) {
groups = this.groups = typeof key === 'string' ? new FastMap() : new Map();
}
let group = groups.get(key);
let element;
if (this.elementSelector) {
try {
element = this.elementSelector(value);
}
catch (err) {
this.error(err);
}
}
else {
element = value;
}
if (!group) {
group = this.subjectSelector ? this.subjectSelector() : new Subject();
groups.set(key, group);
const groupedObservable = new GroupedObservable(key, group, this);
this.destination.next(groupedObservable);
if (this.durationSelector) {
let duration;
try {
duration = this.durationSelector(new GroupedObservable(key, group));
}
catch (err) {
this.error(err);
return;
}
this.add(duration.subscribe(new GroupDurationSubscriber(key, group, this)));
}
}
if (!group.closed) {
group.next(element);
}
}
_error(err) {
const groups = this.groups;
if (groups) {
groups.forEach((group, key) => {
group.error(err);
});
groups.clear();
}
this.destination.error(err);
}
_complete() {
const groups = this.groups;
if (groups) {
groups.forEach((group, key) => {
group.complete();
});
groups.clear();
}
this.destination.complete();
}
removeGroup(key) {
this.groups.delete(key);
}
unsubscribe() {
if (!this.closed) {
this.attemptedToUnsubscribe = true;
if (this.count === 0) {
super.unsubscribe();
}
}
}
}
/**
* We need this JSDoc comment for affecting ESDoc.
* @ignore
* @extends {Ignored}
*/
class GroupDurationSubscriber extends Subscriber {
constructor(key, group, parent) {
super(group);
this.key = key;
this.group = group;
this.parent = parent;
}
_next(value) {
this.complete();
}
_unsubscribe() {
const { parent, key } = this;
this.key = this.parent = null;
if (parent) {
parent.removeGroup(key);
}
}
}
/**
* An Observable representing values belonging to the same group represented by
* a common key. The values emitted by a GroupedObservable come from the source
* Observable. The common key is available as the field `key` on a
* GroupedObservable instance.
*
* @class GroupedObservable<K, T>
*/
export class GroupedObservable extends Observable {
constructor(key, groupSubject, refCountSubscription) {
super();
this.key = key;
this.groupSubject = groupSubject;
this.refCountSubscription = refCountSubscription;
}
_subscribe(subscriber) {
const subscription = new Subscription();
const { refCountSubscription, groupSubject } = this;
if (refCountSubscription && !refCountSubscription.closed) {
subscription.add(new InnerRefCountSubscription(refCountSubscription));
}
subscription.add(groupSubject.subscribe(subscriber));
return subscription;
}
}
/**
* We need this JSDoc comment for affecting ESDoc.
* @ignore
* @extends {Ignored}
*/
class InnerRefCountSubscription extends Subscription {
constructor(parent) {
super();
this.parent = parent;
parent.count++;
}
unsubscribe() {
const parent = this.parent;
if (!parent.closed && !this.closed) {
super.unsubscribe();
parent.count -= 1;
if (parent.count === 0 && parent.attemptedToUnsubscribe) {
parent.unsubscribe();
}
}
}
}
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