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JavaScript
/*---------------------------------------------------------------------------------------------
* Copyright (c) Microsoft Corporation. All rights reserved.
* Licensed under the MIT License. See License.txt in the project root for license information.
*--------------------------------------------------------------------------------------------*/
import { DisposableStore, toDisposable } from '../lifecycle.js';
import { autorun } from './autorun.js';
import { BaseObservable, ConvenientObservable, _setKeepObserved, _setRecomputeInitiallyAndOnChange, getDebugName, getFunctionName, subtransaction, transaction } from './base.js';
import { derived, derivedOpts } from './derived.js';
import { getLogger } from './logging.js';
/**
* Represents an efficient observable whose value never changes.
*/
export function constObservable(value) {
return new ConstObservable(value);
}
class ConstObservable extends ConvenientObservable {
constructor(value) {
super();
this.value = value;
}
get debugName() {
return this.toString();
}
get() {
return this.value;
}
addObserver(observer) {
// NO OP
}
removeObserver(observer) {
// NO OP
}
toString() {
return `Const: ${this.value}`;
}
}
export function waitForState(observable, predicate) {
return new Promise(resolve => {
let didRun = false;
let shouldDispose = false;
const stateObs = observable.map(state => ({ isFinished: predicate(state), state }));
const d = autorun(reader => {
/** @description waitForState */
const { isFinished, state } = stateObs.read(reader);
if (isFinished) {
if (!didRun) {
shouldDispose = true;
}
else {
d.dispose();
}
resolve(state);
}
});
didRun = true;
if (shouldDispose) {
d.dispose();
}
});
}
export function observableFromEvent(event, getValue) {
return new FromEventObservable(event, getValue);
}
export class FromEventObservable extends BaseObservable {
constructor(event, _getValue) {
super();
this.event = event;
this._getValue = _getValue;
this.hasValue = false;
this.handleEvent = (args) => {
var _a;
const newValue = this._getValue(args);
const oldValue = this.value;
const didChange = !this.hasValue || oldValue !== newValue;
let didRunTransaction = false;
if (didChange) {
this.value = newValue;
if (this.hasValue) {
didRunTransaction = true;
subtransaction(FromEventObservable.globalTransaction, (tx) => {
var _a;
(_a = getLogger()) === null || _a === void 0 ? void 0 : _a.handleFromEventObservableTriggered(this, { oldValue, newValue, change: undefined, didChange, hadValue: this.hasValue });
for (const o of this.observers) {
tx.updateObserver(o, this);
o.handleChange(this, undefined);
}
}, () => {
const name = this.getDebugName();
return 'Event fired' + (name ? `: ${name}` : '');
});
}
this.hasValue = true;
}
if (!didRunTransaction) {
(_a = getLogger()) === null || _a === void 0 ? void 0 : _a.handleFromEventObservableTriggered(this, { oldValue, newValue, change: undefined, didChange, hadValue: this.hasValue });
}
};
}
getDebugName() {
return getFunctionName(this._getValue);
}
get debugName() {
const name = this.getDebugName();
return 'From Event' + (name ? `: ${name}` : '');
}
onFirstObserverAdded() {
this.subscription = this.event(this.handleEvent);
}
onLastObserverRemoved() {
this.subscription.dispose();
this.subscription = undefined;
this.hasValue = false;
this.value = undefined;
}
get() {
if (this.subscription) {
if (!this.hasValue) {
this.handleEvent(undefined);
}
return this.value;
}
else {
// no cache, as there are no subscribers to keep it updated
return this._getValue(undefined);
}
}
}
(function (observableFromEvent) {
observableFromEvent.Observer = FromEventObservable;
function batchEventsGlobally(tx, fn) {
let didSet = false;
if (FromEventObservable.globalTransaction === undefined) {
FromEventObservable.globalTransaction = tx;
didSet = true;
}
try {
fn();
}
finally {
if (didSet) {
FromEventObservable.globalTransaction = undefined;
}
}
}
observableFromEvent.batchEventsGlobally = batchEventsGlobally;
})(observableFromEvent || (observableFromEvent = {}));
export function observableSignalFromEvent(debugName, event) {
return new FromEventObservableSignal(debugName, event);
}
class FromEventObservableSignal extends BaseObservable {
constructor(debugName, event) {
super();
this.debugName = debugName;
this.event = event;
this.handleEvent = () => {
transaction((tx) => {
for (const o of this.observers) {
tx.updateObserver(o, this);
o.handleChange(this, undefined);
}
}, () => this.debugName);
};
}
onFirstObserverAdded() {
this.subscription = this.event(this.handleEvent);
}
onLastObserverRemoved() {
this.subscription.dispose();
this.subscription = undefined;
}
get() {
// NO OP
}
}
export function observableSignal(debugNameOrOwner) {
if (typeof debugNameOrOwner === 'string') {
return new ObservableSignal(debugNameOrOwner);
}
else {
return new ObservableSignal(undefined, debugNameOrOwner);
}
}
class ObservableSignal extends BaseObservable {
get debugName() {
var _a;
return (_a = getDebugName(this, this._debugName, undefined, this._owner)) !== null && _a !== void 0 ? _a : 'Observable Signal';
}
constructor(_debugName, _owner) {
super();
this._debugName = _debugName;
this._owner = _owner;
}
trigger(tx, change) {
if (!tx) {
transaction(tx => {
this.trigger(tx, change);
}, () => `Trigger signal ${this.debugName}`);
return;
}
for (const o of this.observers) {
tx.updateObserver(o, this);
o.handleChange(this, change);
}
}
get() {
// NO OP
}
}
/**
* This makes sure the observable is being observed and keeps its cache alive.
*/
export function keepObserved(observable) {
const o = new KeepAliveObserver(false, undefined);
observable.addObserver(o);
return toDisposable(() => {
observable.removeObserver(o);
});
}
_setKeepObserved(keepObserved);
/**
* This converts the given observable into an autorun.
*/
export function recomputeInitiallyAndOnChange(observable, handleValue) {
const o = new KeepAliveObserver(true, handleValue);
observable.addObserver(o);
if (handleValue) {
handleValue(observable.get());
}
else {
observable.reportChanges();
}
return toDisposable(() => {
observable.removeObserver(o);
});
}
_setRecomputeInitiallyAndOnChange(recomputeInitiallyAndOnChange);
class KeepAliveObserver {
constructor(_forceRecompute, _handleValue) {
this._forceRecompute = _forceRecompute;
this._handleValue = _handleValue;
this._counter = 0;
}
beginUpdate(observable) {
this._counter++;
}
endUpdate(observable) {
this._counter--;
if (this._counter === 0 && this._forceRecompute) {
if (this._handleValue) {
this._handleValue(observable.get());
}
else {
observable.reportChanges();
}
}
}
handlePossibleChange(observable) {
// NO OP
}
handleChange(observable, change) {
// NO OP
}
}
export function derivedObservableWithCache(computeFn) {
let lastValue = undefined;
const observable = derived(reader => {
lastValue = computeFn(reader, lastValue);
return lastValue;
});
return observable;
}
/**
* When the items array changes, referential equal items are not mapped again.
*/
export function mapObservableArrayCached(owner, items, map, keySelector) {
let m = new ArrayMap(map, keySelector);
const self = derivedOpts({
debugName: () => getDebugName(m, undefined, map, owner),
owner,
onLastObserverRemoved: () => {
m.dispose();
m = new ArrayMap(map);
}
}, (reader) => {
m.setItems(items.read(reader));
return m.getItems();
});
return self;
}
class ArrayMap {
constructor(_map, _keySelector) {
this._map = _map;
this._keySelector = _keySelector;
this._cache = new Map();
this._items = [];
}
dispose() {
this._cache.forEach(entry => entry.store.dispose());
this._cache.clear();
}
setItems(items) {
const newItems = [];
const itemsToRemove = new Set(this._cache.keys());
for (const item of items) {
const key = this._keySelector ? this._keySelector(item) : item;
let entry = this._cache.get(key);
if (!entry) {
const store = new DisposableStore();
const out = this._map(item, store);
entry = { out, store };
this._cache.set(key, entry);
}
else {
itemsToRemove.delete(key);
}
newItems.push(entry.out);
}
for (const item of itemsToRemove) {
const entry = this._cache.get(item);
entry.store.dispose();
this._cache.delete(item);
}
this._items = newItems;
}
getItems() {
return this._items;
}
}