@n1ru4l/push-pull-async-iterable-iterator

What is @n1ru4l/push-pull-async-iterable-iterator?

@n1ru4l/push-pull-async-iterable-iterator is a utility library for creating and working with async iterable iterators in a push-pull fashion. It allows you to easily create async iterators that can be pushed to and pulled from, making it useful for scenarios like handling streams of data, event handling, and more.

What are @n1ru4l/push-pull-async-iterable-iterator's main functionalities?

Creating a Push-Pull Async Iterable Iterator

This feature allows you to create an async iterable iterator that you can push values to and pull values from. The example demonstrates creating an iterator, pushing values to it, and iterating over those values asynchronously.

const { createPushPullAsyncIterableIterator } = require('@n1ru4l/push-pull-async-iterable-iterator');

const { asyncIterableIterator, pushValue, stop } = createPushPullAsyncIterableIterator();

(async () => {
  for await (const value of asyncIterableIterator) {
    console.log(value);
  }
})();

pushValue(1);
pushValue(2);
pushValue(3);
stop();

Handling Errors

This feature allows you to handle errors within the async iterable iterator. The example demonstrates pushing an error to the iterator and handling it within the async iteration loop.

const { createPushPullAsyncIterableIterator } = require('@n1ru4l/push-pull-async-iterable-iterator');

const { asyncIterableIterator, pushValue, pushError, stop } = createPushPullAsyncIterableIterator();

(async () => {
  try {
    for await (const value of asyncIterableIterator) {
      console.log(value);
    }
  } catch (error) {
    console.error('Error:', error);
  }
})();

pushValue(1);
pushError(new Error('Something went wrong!'));
stop();

Stopping the Iterator

This feature allows you to stop the async iterable iterator. The example demonstrates pushing values to the iterator and then stopping it, which ends the iteration loop.

const { createPushPullAsyncIterableIterator } = require('@n1ru4l/push-pull-async-iterable-iterator');

const { asyncIterableIterator, pushValue, stop } = createPushPullAsyncIterableIterator();

(async () => {
  for await (const value of asyncIterableIterator) {
    console.log(value);
  }
  console.log('Iterator stopped');
})();

pushValue(1);
pushValue(2);
stop();

Other packages similar to @n1ru4l/push-pull-async-iterable-iterator

rxjs

RxJS is a library for reactive programming using Observables, to make it easier to compose asynchronous or callback-based code. It provides similar functionality to @n1ru4l/push-pull-async-iterable-iterator in terms of handling streams of data and events, but it is more comprehensive and includes a wide range of operators for transforming and combining streams.

most

Most.js is a high-performance FRP (Functional Reactive Programming) library. It provides a similar push-pull mechanism for handling streams of data and events. Compared to @n1ru4l/push-pull-async-iterable-iterator, Most.js focuses on performance and offers a rich set of operators for stream manipulation.

baconjs

Bacon.js is a small functional reactive programming library for JavaScript. It provides similar functionality for handling streams of data and events. Bacon.js offers a more functional approach compared to @n1ru4l/push-pull-async-iterable-iterator and includes a variety of combinators and operators for working with streams.

README

@n1ru4l/push-pull-async-iterable-iterator

Create an AsyncIterableIterator from anything while handling back-pressure!

yarn install -E @n1ru4l/push-pull-async-iterable-iterator

Standalone Usage

import { PushPullAsyncIterableIterator } from "@n1ru4l/push-pull-async-iterable-iterator";

const iterator = new PushPullAsyncIterableIterator();
iterator.push(1);
iterator.push(2);
iterator.push(3);

// prints 1, 2, 3
for await (const value of iterator) {
  console.log(value);
}

Wrap a Sink

import { makeAsyncIterableIteratorFromSink } from "@n1ru4l/push-pull-async-iterable-iterator";
// let's use some GraphQL client :)
import { createClient } from "graphql-ws/lib/use/ws";

const client = createClient({
  url: "ws://localhost:3000/graphql"
});

const asyncIterableIterator = makeAsyncIterableIteratorFromSink(sink => {
  const dispose = client.subscribe(
    {
      query: "{ hello }"
    },
    {
      next: sink.next,
      error: sink.error,
      complete: sink.complete
    }
  );
  return () => dispose();
});

for await (const value of asyncIterableIterator) {
  console.log(value);
}

Apply an AsyncIterableIterator to a sink

import Observable from "zen-observable";
import {
  PushPullAsyncIterableIterator,
  applyAsyncIterableIteratorToSink
} from "@n1ru4l/push-pull-async-iterable-iterator";

const iterator = new PushPullAsyncIterableIterator();

const observable = new Observable(sink => {
  const dispose = applyAsyncIterableIteratorToSink(iterator, sink);
  // dispose will be called when the observable subscription got destroyed
  // the dispose call will ensure that the async iterator is completed.
  return () => dispose();
});

const subscription = observable.subscribe({
  next: console.log,
  complete: () => console.log("done."),
  error: () => console.log("error.")
});

const interval = setInterval(() => {
  iterator.push("hi");
}, 1000);

setTimeout(() => {
  subscription.unsubscribe();
  clearInterval(interval);
}, 5000);

Put it all together

import { Observable, RequestParameters, Variables } from "relay-runtime";
import { createClient } from "graphql-ws/lib/use/ws";
import {
  makeAsyncIterableFromSink,
  applyAsyncIterableIteratorToSink
} from "@n1ru4l/push-pull-async-iterable-iterator";
import { createLiveQueryPatchInflator } from "@n1ru4l/graphql-live-query-patch";

const client = createClient({
  url: "ws://localhost:3000/graphql"
});

export const execute = (request: RequestParameters, variables: Variables) => {
  if (!request.text) {
    throw new Error("Missing document.");
  }
  const query = request.text;

  return Observable.create<GraphQLResponse>(sink => {
    // Create our asyncIterator from a Sink
    const executionResultIterator = makeAsyncIterableFromSink(wsSink => {
      const dispose = client.subscribe({ query }, wsSink);
      return () => dispose();
    });

    // apply some middleware to our asyncIterator
    const compositeIterator = createLiveQueryPatchInflator(
      executionResultIterator
    );

    // Apply our async iterable to the relay sink
    // unfortunately relay cannot consume an async iterable right now.
    const dispose = applyAsyncIterableIteratorToSink(compositeIterator, sink);
    // dispose will be called by relay when the observable is disposed
    // the dispose call will ensure that the async iterator is completed.
    return () => dispose();
  });
};

---

TSDX User Guide

Congrats! You just saved yourself hours of work by bootstrapping this project with TSDX. Let’s get you oriented with what’s here and how to use it.

This TSDX setup is meant for developing libraries (not apps!) that can be published to NPM. If you’re looking to build a Node app, you could use ts-node-dev, plain ts-node, or simple tsc.

If you’re new to TypeScript, checkout this handy cheatsheet

Commands

TSDX scaffolds your new library inside /src.

To run TSDX, use:

npm start # or yarn start

This builds to /dist and runs the project in watch mode so any edits you save inside src causes a rebuild to /dist.

To do a one-off build, use npm run build or yarn build.

To run tests, use npm test or yarn test.

Configuration

Code quality is set up for you with prettier, husky, and lint-staged. Adjust the respective fields in package.json accordingly.

Jest

Jest tests are set up to run with npm test or yarn test.

Bundle Analysis

size-limit is set up to calculate the real cost of your library with npm run size and visualize the bundle with npm run analyze.

Setup Files

This is the folder structure we set up for you:

/src
  index.tsx       # EDIT THIS
/test
  blah.test.tsx   # EDIT THIS
.gitignore
package.json
README.md         # EDIT THIS
tsconfig.json

Rollup

TSDX uses Rollup as a bundler and generates multiple rollup configs for various module formats and build settings. See Optimizations for details.

TypeScript

tsconfig.json is set up to interpret dom and esnext types, as well as react for jsx. Adjust according to your needs.

Continuous Integration

GitHub Actions

Two actions are added by default:

• main which installs deps w/ cache, lints, tests, and builds on all pushes against a Node and OS matrix
• size which comments cost comparison of your library on every pull request using size-limit

Optimizations

Please see the main tsdx optimizations docs. In particular, know that you can take advantage of development-only optimizations:

// ./types/index.d.ts
declare var __DEV__: boolean;

// inside your code...
if (__DEV__) {
  console.log("foo");
}

You can also choose to install and use invariant and warning functions.

Module Formats

CJS, ESModules, and UMD module formats are supported.

The appropriate paths are configured in package.json and dist/index.js accordingly. Please report if any issues are found.

Named Exports

Per Palmer Group guidelines, always use named exports. Code split inside your React app instead of your React library.

Including Styles

There are many ways to ship styles, including with CSS-in-JS. TSDX has no opinion on this, configure how you like.

For vanilla CSS, you can include it at the root directory and add it to the files section in your package.json, so that it can be imported separately by your users and run through their bundler's loader.

Publishing to NPM

We recommend using np.