Init

node_modules/p-cancelable/index.js

@@ -0,0 +1,119 @@
+export class CancelError extends Error {
+	constructor(reason) {
+		super(reason || 'Promise was canceled');
+		this.name = 'CancelError';
+	}
+
+	get isCanceled() {
+		return true;
+	}
+}
+
+const promiseState = Object.freeze({
+	pending: Symbol('pending'),
+	canceled: Symbol('canceled'),
+	resolved: Symbol('resolved'),
+	rejected: Symbol('rejected'),
+});
+
+export default class PCancelable {
+	static fn(userFunction) {
+		return (...arguments_) => new PCancelable((resolve, reject, onCancel) => {
+			arguments_.push(onCancel);
+			userFunction(...arguments_).then(resolve, reject);
+		});
+	}
+
+	#cancelHandlers = [];
+	#rejectOnCancel = true;
+	#state = promiseState.pending;
+	#promise;
+	#reject;
+
+	constructor(executor) {
+		this.#promise = new Promise((resolve, reject) => {
+			this.#reject = reject;
+
+			const onResolve = value => {
+				if (this.#state !== promiseState.canceled || !onCancel.shouldReject) {
+					resolve(value);
+					this.#setState(promiseState.resolved);
+				}
+			};
+
+			const onReject = error => {
+				if (this.#state !== promiseState.canceled || !onCancel.shouldReject) {
+					reject(error);
+					this.#setState(promiseState.rejected);
+				}
+			};
+
+			const onCancel = handler => {
+				if (this.#state !== promiseState.pending) {
+					throw new Error(`The \`onCancel\` handler was attached after the promise ${this.#state.description}.`);
+				}
+
+				this.#cancelHandlers.push(handler);
+			};
+
+			Object.defineProperties(onCancel, {
+				shouldReject: {
+					get: () => this.#rejectOnCancel,
+					set: boolean => {
+						this.#rejectOnCancel = boolean;
+					},
+				},
+			});
+
+			executor(onResolve, onReject, onCancel);
+		});
+	}
+
+	// eslint-disable-next-line unicorn/no-thenable
+	then(onFulfilled, onRejected) {
+		return this.#promise.then(onFulfilled, onRejected);
+	}
+
+	catch(onRejected) {
+		return this.#promise.catch(onRejected);
+	}
+
+	finally(onFinally) {
+		return this.#promise.finally(onFinally);
+	}
+
+	cancel(reason) {
+		if (this.#state !== promiseState.pending) {
+			return;
+		}
+
+		this.#setState(promiseState.canceled);
+
+		if (this.#cancelHandlers.length > 0) {
+			try {
+				for (const handler of this.#cancelHandlers) {
+					handler();
+				}
+			} catch (error) {
+				this.#reject(error);
+				return;
+			}
+		}
+
+		if (this.#rejectOnCancel) {
+			this.#reject(new CancelError(reason));
+		}
+	}
+
+	get isCanceled() {
+		return this.#state === promiseState.canceled;
+	}
+
+	#setState(state) {
+		if (this.#state === promiseState.pending) {
+			this.#state = state;
+		}
+	}
+}
+
+Object.setPrototypeOf(PCancelable.prototype, Promise.prototype);