Promise/Callback fn wrappers for then-pug (which is generators based)

asyncWrappers.pug

//- will only work with the `npm install then-pug` module instead of default `pug`
//-  passed in locals are: sendmail (node module), insp which is require('util').inspect, and just passed in Promise

-
	// for functions having the second param as callback (e.g. nodejs fs.readFile)
	function syncifyCb(fn) {
		return function* (param1) {
			let result = null;
			
			yield function* () {
				yield new Promise(function (ret) {
					fn(
						param1 || undefined,
						function(err,data) { ret({err,data}); }
					);
				})
			}().next().value.then(function(r) { result = r; });

			return result;
		}
	};
	
	//syncify
	let sendmailSync = syncifyCb(sendmail);
	
	//exec
	let res = yield sendmailSync({
		from: 'no-reply@test.test',
		to: 'test@test.test',
		subject: 'test sendmail',
		html: 'Hello world.'
	});

pre= insp(res)


-
	// for directly wrapping a promise to await for
	function syncifyPromise(fn) {
		return function* () {
			let result = null;
			
			yield function* () {
				yield fn
			}().next().value.then(function(r) { result = r; });

			return result;
		}()
	};


	const start = Date.now(); // mesure the 1s
	
	// new Promise stars resolving async the moment it is declared - syncify + exec
	let res2 = yield syncifyPromise(
		// test promise
		new Promise( function(ret) {
			setTimeout(function() {ret('sleep'); }, 1000); // 1s delay
		})
	);

	const ms = Date.now() - start;


pre= insp(res2) + ` -> ${ms}ms`



-
	// for typical facory functions returning a promise to be awaited for  (e.g. node fs.promises.readFile)
	function syncifyPromiseFactory(fn) {
		return function* (param1) {
			let result = null;
			
			yield function* () {
				yield fn(param1)
			}().next().value.then(function(r) { result = r; });

			return result;
		}
	};

	
	// test factory
	let makeX = function(options = {}) {

		return new Promise( function(ret) {
			setTimeout(function() {ret('sleep'); }, options.ms || 1000); // 1s delay
		});

	};

	// syncify
	let makeXSync = syncifyPromiseFactory(makeX);

	const startX = Date.now(); // mesure the 1s
	
	// exec
	let res3 = yield makeX({ms: 500});

	const msX = Date.now() - startX;
	
	
	// example2 - passed in on locals:  {.., CouchDB: nano(serviceUrlInclCreds), .. }
	//let list = syncifyPromiseFactory( CouchDB.db.use('requests').list );
	//let requests = yield list();


pre= insp(res3) + ` -> ${msX}ms`


div done