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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 { IReader, IObservable, IObserver } from 'vs/base/common/observableImpl/base';
import { getLogger } from 'vs/base/common/observableImpl/logging';
export function autorun(debugName: string, fn: (reader: IReader) => void): IDisposable {
return new AutorunObserver(debugName, fn, undefined);
}
interface IChangeContext {
readonly changedObservable: IObservable<any, any>;
readonly change: unknown;
didChange<T, TChange>(observable: IObservable<T, TChange>): this is { change: TChange };
}
export function autorunHandleChanges(
debugName: string,
options: {
/**
* Returns if this change should cause a re-run of the autorun.
*/
handleChange: (context: IChangeContext) => boolean;
},
fn: (reader: IReader) => void
): IDisposable {
return new AutorunObserver(debugName, fn, options.handleChange);
}
export function autorunWithStore(
fn: (reader: IReader, store: DisposableStore) => void,
debugName: string
): IDisposable {
const store = new DisposableStore();
const disposable = autorun(
debugName,
reader => {
store.clear();
fn(reader, store);
}
);
return toDisposable(() => {
disposable.dispose();
store.dispose();
});
}
export class AutorunObserver implements IObserver, IReader, IDisposable {
public needsToRun = true;
private updateCount = 0;
private disposed = false;
/**
* The actual dependencies.
*/
private _dependencies = new Set<IObservable<any>>();
public get dependencies() {
return this._dependencies;
}
/**
* Dependencies that have to be removed when {@link runFn} ran through.
*/
private staleDependencies = new Set<IObservable<any>>();
constructor(
public readonly debugName: string,
private readonly runFn: (reader: IReader) => void,
private readonly _handleChange: ((context: IChangeContext) => boolean) | undefined
) {
getLogger()?.handleAutorunCreated(this);
this.runIfNeeded();
}
public subscribeTo<T>(observable: IObservable<T>) {
// In case the run action disposes the autorun
if (this.disposed) {
return;
}
this._dependencies.add(observable);
if (!this.staleDependencies.delete(observable)) {
observable.addObserver(this);
}
}
public handleChange<T, TChange>(observable: IObservable<T, TChange>, change: TChange): void {
const shouldReact = this._handleChange ? this._handleChange({
changedObservable: observable,
change,
didChange: o => o === observable as any,
}) : true;
this.needsToRun = this.needsToRun || shouldReact;
if (this.updateCount === 0) {
this.runIfNeeded();
}
}
public beginUpdate(): void {
this.updateCount++;
}
public endUpdate(): void {
this.updateCount--;
if (this.updateCount === 0) {
this.runIfNeeded();
}
}
private runIfNeeded(): void {
if (!this.needsToRun) {
return;
}
// Assert: this.staleDependencies is an empty set.
const emptySet = this.staleDependencies;
this.staleDependencies = this._dependencies;
this._dependencies = emptySet;
this.needsToRun = false;
getLogger()?.handleAutorunTriggered(this);
try {
this.runFn(this);
} finally {
// We don't want our observed observables to think that they are (not even temporarily) not being observed.
// Thus, we only unsubscribe from observables that are definitely not read anymore.
for (const o of this.staleDependencies) {
o.removeObserver(this);
}
this.staleDependencies.clear();
}
}
public dispose(): void {
this.disposed = true;
for (const o of this._dependencies) {
o.removeObserver(this);
}
this._dependencies.clear();
}
public toString(): string {
return `Autorun<${this.debugName}>`;
}
}
export namespace autorun {
export const Observer = AutorunObserver;
}
export function autorunDelta<T>(
name: string,
observable: IObservable<T>,
handler: (args: { lastValue: T | undefined; newValue: T }) => void
): IDisposable {
let _lastValue: T | undefined;
return autorun(name, (reader) => {
const newValue = observable.read(reader);
const lastValue = _lastValue;
_lastValue = newValue;
handler({ lastValue, newValue });
});
}
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