@thi.ng/transducers-async/iterator.js

Async versions of various highly composable transducers, reducers and iterators

import { NO_OP, SEMAPHORE } from "@thi.ng/api/api";
import { isAsyncIterable } from "@thi.ng/checks/is-async-iterable";
import { isIterable } from "@thi.ng/checks/is-iterable";
import { isReduced } from "@thi.ng/transducers/reduced";
import { ensureAsyncTransducer } from "./ensure.js";
import { push } from "./push.js";
async function* iterator1(xform, src) {
  const [_, complete, reduce] = ensureAsyncTransducer(xform)([NO_OP, NO_OP, (_2, x) => x]);
  for await (let x of src) {
    let y = await reduce(SEMAPHORE, x);
    if (isReduced(y)) {
      const res = await complete(y.deref());
      if (res !== SEMAPHORE) {
        yield res;
      }
      return;
    }
    if (y !== SEMAPHORE) {
      yield y;
    }
  }
}
async function* iterator(xform, src) {
  const [_, complete, reduce] = ensureAsyncTransducer(
    xform
  )(push());
  for await (let x of src) {
    const y = await reduce([], x);
    if (isReduced(y)) {
      yield* await complete(y.deref());
      return;
    }
    if (y.length) {
      yield* y;
    }
  }
  yield* await complete([]);
}
const __iter = (xform, args, impl = iterator1) => {
  const n = args.length - 1;
  return isIterable(args[n]) || isAsyncIterable(args[n]) ? args.length > 1 ? impl(xform.apply(null, args.slice(0, n)), args[n]) : impl(xform(), args[0]) : void 0;
};
export {
  __iter,
  iterator,
  iterator1
};