AsyncIterator for Observable Using Ag() coroutine

gen-async.js

function createAsyncIterator() {
  const self = this;
  return ag(function*() {
    const resume = [];
    const values = [];

    const subscription = self.materialize().subscribe(value => {
      values.push(value);
      resume.splice(0).forEach(r => r());
    });
    
    try {
      while (true) {
        while (values.length > 0) {
          const v = values.shift();
          if (v.kind == 'N') yield v.value;
          else if (v.kind == 'E') throw v.error;
          else return;
        }
        yield new Promise(r => resume.push(r));
      }
    } finally {
      subscription.unsubscribe();
    }
  });
}

ag()는 https://gist.github.com/jooyunghan/c04d1d9a58cd153be114b8f501c1f5b3 참고