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

Async versions of various highly composable transducers, reducers and iterators

import { isReduced } from "@thi.ng/transducers/reduced";
import { __iter, iterator } from "./iterator.js";
function rechunk(...args) {
  const iter = __iter(rechunk, args, iterator);
  if (iter) return iter;
  return ([init, complete, reduce]) => {
    let buf = "";
    const re = args[0] || /\r?\n/;
    return [
      init,
      async (acc) => {
        if (buf) acc = await reduce(acc, buf);
        return complete(acc);
      },
      async (acc, chunk) => {
        buf += chunk;
        const parts = buf.split(re);
        if (parts.length > 1) {
          buf = parts.pop();
          for (const part of parts) {
            acc = await reduce(acc, part);
            if (isReduced(acc)) {
              buf = "";
              break;
            }
          }
        }
        return acc;
      }
    ];
  };
}
export {
  rechunk
};