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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 { CancellationToken, CancellationTokenSource } from 'vs/base/common/cancellation';
import { IDisposable } from 'vs/base/common/lifecycle';
export interface CacheResult<T> extends IDisposable {
promise: Promise<T>;
}
export class Cache<T> {
private result: CacheResult<T> | null = null;
constructor(private task: (ct: CancellationToken) => Promise<T>) { }
get(): CacheResult<T> {
if (this.result) {
return this.result;
}
const cts = new CancellationTokenSource();
const promise = this.task(cts.token);
this.result = {
promise,
dispose: () => {
this.result = null;
cts.cancel();
cts.dispose();
}
};
return this.result;
}
}
/**
* Uses a LRU cache to make a given parametrized function cached.
* Caches just the last value.
* The key must be JSON serializable.
*/
export class LRUCachedFunction<TArg, TComputed> {
private lastCache: TComputed | undefined = undefined;
private lastArgKey: string | undefined = undefined;
constructor(private readonly fn: (arg: TArg) => TComputed) {
}
public get(arg: TArg): TComputed {
const key = JSON.stringify(arg);
if (this.lastArgKey !== key) {
this.lastArgKey = key;
this.lastCache = this.fn(arg);
}
return this.lastCache!;
}
}
/**
* Uses an unbounded cache (referential equality) to memoize the results of the given function.
*/
export class CachedFunction<TArg, TValue> {
private readonly _map = new Map<TArg, TValue>();
public get cachedValues(): ReadonlyMap<TArg, TValue> {
return this._map;
}
constructor(private readonly fn: (arg: TArg) => TValue) { }
public get(arg: TArg): TValue {
if (this._map.has(arg)) {
return this._map.get(arg)!;
}
const value = this.fn(arg);
this._map.set(arg, value);
return value;
}
}
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