/
utils.ts
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/
utils.ts
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/*---------------------------------------------------------------------------------------------
* Copyright (c) Microsoft Corporation. All rights reserved.
* Licensed under the MIT License. See License.txt in the project root for license information.
*--------------------------------------------------------------------------------------------*/
import { DisposableStore, IDisposable, toDisposable } from 'vs/base/common/lifecycle';
import { autorun } from 'vs/base/common/observableImpl/autorun';
import { IObservable, BaseObservable, transaction, IReader, ITransaction, ConvenientObservable, IObserver, observableValue, getFunctionName } from 'vs/base/common/observableImpl/base';
import { derived } from 'vs/base/common/observableImpl/derived';
import { Event } from 'vs/base/common/event';
import { getLogger } from 'vs/base/common/observableImpl/logging';
export function constObservable<T>(value: T): IObservable<T> {
return new ConstObservable(value);
}
class ConstObservable<T> extends ConvenientObservable<T, void> {
constructor(private readonly value: T) {
super();
}
public override get debugName(): string {
return this.toString();
}
public get(): T {
return this.value;
}
public addObserver(observer: IObserver): void {
// NO OP
}
public removeObserver(observer: IObserver): void {
// NO OP
}
override toString(): string {
return `Const: ${this.value}`;
}
}
export function observableFromPromise<T>(promise: Promise<T>): IObservable<{ value?: T }> {
const observable = observableValue<{ value?: T }>('promiseValue', {});
promise.then((value) => {
observable.set({ value }, undefined);
});
return observable;
}
export function waitForState<T, TState extends T>(observable: IObservable<T>, predicate: (state: T) => state is TState): Promise<TState>;
export function waitForState<T>(observable: IObservable<T>, predicate: (state: T) => boolean): Promise<T>;
export function waitForState<T>(observable: IObservable<T>, predicate: (state: T) => boolean): Promise<T> {
return new Promise(resolve => {
let didRun = false;
let shouldDispose = false;
const d = autorun('waitForState', reader => {
const currentState = observable.read(reader);
if (predicate(currentState)) {
if (!didRun) {
shouldDispose = true;
} else {
d.dispose();
}
resolve(currentState);
}
});
didRun = true;
if (shouldDispose) {
d.dispose();
}
});
}
export function observableFromEvent<T, TArgs = unknown>(
event: Event<TArgs>,
getValue: (args: TArgs | undefined) => T
): IObservable<T> {
return new FromEventObservable(event, getValue);
}
export class FromEventObservable<TArgs, T> extends BaseObservable<T> {
private value: T | undefined;
private hasValue = false;
private subscription: IDisposable | undefined;
constructor(
private readonly event: Event<TArgs>,
private readonly getValue: (args: TArgs | undefined) => T
) {
super();
}
private getDebugName(): string | undefined {
return getFunctionName(this.getValue);
}
public get debugName(): string {
const name = this.getDebugName();
return 'From Event' + (name ? `: ${name}` : '');
}
protected override onFirstObserverAdded(): void {
this.subscription = this.event(this.handleEvent);
}
private readonly handleEvent = (args: TArgs | undefined) => {
const newValue = this.getValue(args);
const didChange = !this.hasValue || this.value !== newValue;
getLogger()?.handleFromEventObservableTriggered(this, { oldValue: this.value, newValue, change: undefined, didChange });
if (didChange) {
this.value = newValue;
if (this.hasValue) {
transaction(
(tx) => {
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;
}
};
protected override onLastObserverRemoved(): void {
this.subscription!.dispose();
this.subscription = undefined;
this.hasValue = false;
this.value = undefined;
}
public get(): T {
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);
}
}
}
export namespace observableFromEvent {
export const Observer = FromEventObservable;
}
export function observableSignalFromEvent(
debugName: string,
event: Event<any>
): IObservable<void> {
return new FromEventObservableSignal(debugName, event);
}
class FromEventObservableSignal extends BaseObservable<void> {
private subscription: IDisposable | undefined;
constructor(
public readonly debugName: string,
private readonly event: Event<any>,
) {
super();
}
protected override onFirstObserverAdded(): void {
this.subscription = this.event(this.handleEvent);
}
private readonly handleEvent = () => {
transaction(
(tx) => {
for (const o of this.observers) {
tx.updateObserver(o, this);
o.handleChange(this, undefined);
}
},
() => this.debugName
);
};
protected override onLastObserverRemoved(): void {
this.subscription!.dispose();
this.subscription = undefined;
}
public override get(): void {
// NO OP
}
}
export function observableSignal<TDelta = void>(
debugName: string
): IObservableSignal<TDelta> {
return new ObservableSignal<TDelta>(debugName);
}
export interface IObservableSignal<TChange> extends IObservable<void, TChange> {
trigger(tx: ITransaction | undefined, change: TChange): void;
}
class ObservableSignal<TChange> extends BaseObservable<void, TChange> implements IObservableSignal<TChange> {
constructor(
public readonly debugName: string
) {
super();
}
public trigger(tx: ITransaction | undefined, change: TChange): void {
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);
}
}
public override get(): void {
// NO OP
}
}
export function debouncedObservable<T>(observable: IObservable<T>, debounceMs: number, disposableStore: DisposableStore): IObservable<T | undefined> {
const debouncedObservable = observableValue<T | undefined>('debounced', undefined);
let timeout: any = undefined;
disposableStore.add(autorun('debounce', reader => {
const value = observable.read(reader);
if (timeout) {
clearTimeout(timeout);
}
timeout = setTimeout(() => {
transaction(tx => {
debouncedObservable.set(value, tx);
});
}, debounceMs);
}));
return debouncedObservable;
}
export function wasEventTriggeredRecently(event: Event<any>, timeoutMs: number, disposableStore: DisposableStore): IObservable<boolean> {
const observable = observableValue('triggeredRecently', false);
let timeout: any = undefined;
disposableStore.add(event(() => {
observable.set(true, undefined);
if (timeout) {
clearTimeout(timeout);
}
timeout = setTimeout(() => {
observable.set(false, undefined);
}, timeoutMs);
}));
return observable;
}
/**
* This ensures the observable is being observed.
* Observed observables (such as {@link derived}s) can maintain a cache, as they receive invalidation events.
* Unobserved observables are forced to recompute their value from scratch every time they are read.
*
* @param observable the observable to keep alive
* @param forceRecompute if true, the observable will be eagerly recomputed after it changed.
* Use this if recomputing the observables causes side-effects.
*/
export function keepAlive(observable: IObservable<any>, forceRecompute?: boolean): IDisposable {
const o = new KeepAliveObserver(forceRecompute ?? false);
observable.addObserver(o);
return toDisposable(() => {
observable.removeObserver(o);
});
}
class KeepAliveObserver implements IObserver {
private counter = 0;
constructor(private readonly forceRecompute: boolean) { }
beginUpdate<T>(observable: IObservable<T, void>): void {
this.counter++;
}
endUpdate<T>(observable: IObservable<T, void>): void {
this.counter--;
if (this.counter === 0 && this.forceRecompute) {
observable.reportChanges();
}
}
handlePossibleChange<T>(observable: IObservable<T, unknown>): void {
// NO OP
}
handleChange<T, TChange>(observable: IObservable<T, TChange>, change: TChange): void {
// NO OP
}
}
export function derivedObservableWithCache<T>(name: string, computeFn: (reader: IReader, lastValue: T | undefined) => T): IObservable<T> {
let lastValue: T | undefined = undefined;
const observable = derived(name, reader => {
lastValue = computeFn(reader, lastValue);
return lastValue;
});
return observable;
}
export function derivedObservableWithWritableCache<T>(name: string, computeFn: (reader: IReader, lastValue: T | undefined) => T): IObservable<T> & { clearCache(transaction: ITransaction): void } {
let lastValue: T | undefined = undefined;
const counter = observableValue('derivedObservableWithWritableCache.counter', 0);
const observable = derived(name, reader => {
counter.read(reader);
lastValue = computeFn(reader, lastValue);
return lastValue;
});
return Object.assign(observable, {
clearCache: (transaction: ITransaction) => {
lastValue = undefined;
counter.set(counter.get() + 1, transaction);
},
});
}