TypeScript Event.once方法代碼示例

function extractEntry(stream: Readable, fileName: string, mode: number, targetPath: string, options: IOptions, token: CancellationToken): Promise<void> {
	const dirName = path.dirname(fileName);
	const targetDirName = path.join(targetPath, dirName);
	if (targetDirName.indexOf(targetPath) !== 0) {
		return Promise.reject(new Error(nls.localize('invalid file', "Error extracting {0}. Invalid file.", fileName)));
	}
	const targetFileName = path.join(targetPath, fileName);

	let istream: WriteStream;

	Event.once(token.onCancellationRequested)(() => {
		if (istream) {
			istream.destroy();
		}
	});

	return Promise.resolve(mkdirp(targetDirName, undefined, token)).then(() => new Promise<void>((c, e) => {
		if (token.isCancellationRequested) {
			return;
		}

		try {
			istream = createWriteStream(targetFileName, { mode });
			istream.once('close', () => c());
			istream.once('error', e);
			stream.once('error', e);
			stream.pipe(istream);
		} catch (error) {
			e(error);
		}
	}));
}

function extractZip(zipfile: ZipFile, targetPath: string, options: IOptions, logService: ILogService, token: CancellationToken): Promise<void> {
	let last = createCancelablePromise<void>(() => Promise.resolve());
	let extractedEntriesCount = 0;

	Event.once(token.onCancellationRequested)(() => {
		logService.debug(targetPath, 'Cancelled.');
		last.cancel();
		zipfile.close();
	});

	return new Promise((c, e) => {
		const throttler = new Sequencer();

		const readNextEntry = (token: CancellationToken) => {
			if (token.isCancellationRequested) {
				return;
			}

			extractedEntriesCount++;
			zipfile.readEntry();
		};

		zipfile.once('error', e);
		zipfile.once('close', () => last.then(() => {
			if (token.isCancellationRequested || zipfile.entryCount === extractedEntriesCount) {
				c();
			} else {
				e(new ExtractError('Incomplete', new Error(nls.localize('incompleteExtract', "Incomplete. Found {0} of {1} entries", extractedEntriesCount, zipfile.entryCount))));
			}
		}, e));
		zipfile.readEntry();
		zipfile.on('entry', (entry: Entry) => {

			if (token.isCancellationRequested) {
				return;
			}

			if (!options.sourcePathRegex.test(entry.fileName)) {
				readNextEntry(token);
				return;
			}

			const fileName = entry.fileName.replace(options.sourcePathRegex, '');

			// directory file names end with '/'
			if (/\/$/.test(fileName)) {
				const targetFileName = path.join(targetPath, fileName);
				last = createCancelablePromise(token => mkdirp(targetFileName, void 0, token).then(() => readNextEntry(token)).then(void 0, e));
				return;
			}

			const stream = ninvoke(zipfile, zipfile.openReadStream, entry);
			const mode = modeFromEntry(entry);

			last = createCancelablePromise(token => throttler.queue(() => stream.then(stream => extractEntry(stream, fileName, mode, targetPath, options, token).then(() => readNextEntry(token)))).then(null!, e));
		});
	});
}

	private triggerAriaAlert(notifiation: INotificationViewItem): void {

		// Trigger the alert again whenever the label changes
		const listener = notifiation.onDidLabelChange(e => {
			if (e.kind === NotificationViewItemLabelKind.MESSAGE) {
				this.doTriggerAriaAlert(notifiation);
			}
		});

		Event.once(notifiation.onDidClose)(() => listener.dispose());

		this.doTriggerAriaAlert(notifiation);
	}

function ensureWriteFileQueue(queueKey: string): Queue<void> {
	let writeFileQueue = writeFilePathQueue[queueKey];
	if (!writeFileQueue) {
		writeFileQueue = new Queue<void>();
		writeFilePathQueue[queueKey] = writeFileQueue;

		const onFinish = Event.once(writeFileQueue.onFinished);
		onFinish(() => {
			delete writeFilePathQueue[queueKey];
			writeFileQueue.dispose();
		});
	}

	return writeFileQueue;
}

function ensureWriteFileQueue(queueKey: string): Queue<void> {
	const existingWriteFileQueue = writeFilePathQueues.get(queueKey);
	if (existingWriteFileQueue) {
		return existingWriteFileQueue;
	}

	const writeFileQueue = new Queue<void>();
	writeFilePathQueues.set(queueKey, writeFileQueue);

	const onFinish = Event.once(writeFileQueue.onFinished);
	onFinish(() => {
		writeFilePathQueues.delete(queueKey);
		writeFileQueue.dispose();
	});

	return writeFileQueue;
}