Icard/angular-clarity-master(work.../node_modules/lit-html/development/directives/private-async-helpers.js

83 lines
2.4 KiB
JavaScript

/**
* @license
* Copyright 2021 Google LLC
* SPDX-License-Identifier: BSD-3-Clause
*/
// Note, this module is not included in package exports so that it's private to
// our first-party directives. If it ends up being useful, we can open it up and
// export it.
/**
* Helper to iterate an AsyncIterable in its own closure.
* @param iterable The iterable to iterate
* @param callback The callback to call for each value. If the callback returns
* `false`, the loop will be broken.
*/
export const forAwaitOf = async (iterable, callback) => {
for await (const v of iterable) {
if ((await callback(v)) === false) {
return;
}
}
};
/**
* Holds a reference to an instance that can be disconnected and reconnected,
* so that a closure over the ref (e.g. in a then function to a promise) does
* not strongly hold a ref to the instance. Approximates a WeakRef but must
* be manually connected & disconnected to the backing instance.
*/
export class PseudoWeakRef {
constructor(ref) {
this._ref = ref;
}
/**
* Disassociates the ref with the backing instance.
*/
disconnect() {
this._ref = undefined;
}
/**
* Reassociates the ref with the backing instance.
*/
reconnect(ref) {
this._ref = ref;
}
/**
* Retrieves the backing instance (will be undefined when disconnected)
*/
deref() {
return this._ref;
}
}
/**
* A helper to pause and resume waiting on a condition in an async function
*/
export class Pauser {
constructor() {
this._promise = undefined;
this._resolve = undefined;
}
/**
* When paused, returns a promise to be awaited; when unpaused, returns
* undefined. Note that in the microtask between the pauser being resumed
* an an await of this promise resolving, the pauser could be paused again,
* hence callers should check the promise in a loop when awaiting.
* @returns A promise to be awaited when paused or undefined
*/
get() {
return this._promise;
}
/**
* Creates a promise to be awaited
*/
pause() {
this._promise ??= new Promise((resolve) => (this._resolve = resolve));
}
/**
* Resolves the promise which may be awaited
*/
resume() {
this._resolve?.();
this._promise = this._resolve = undefined;
}
}
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