iter-tools-es/impls/$split-groups/async-split-groups.js

The iterable toolbox

const {
  asyncIterableCurry
} = require('../../internal/async-iterable.js');

const {
  __asyncSpliterateGrouped
} = require('../$spliterate-grouped/async-spliterate-grouped.js');

const {
  __asyncPeekerate
} = require('../$peekerate/async-peekerate.js');

const initialKey = Symbol('initial group key');

async function* asyncGroupingSpliterator(split, {
  getKey
}, source) {
  const peekr = await __asyncPeekerate(source);
  let key = initialKey;
  let idx = 0;

  while (!peekr.done) {
    const lastKey = key;
    key = await getKey(peekr.value, idx++);

    if (lastKey !== key) {
      yield split;
      yield key;
    }

    yield peekr.value;
    await peekr.advance();
  }
}

function __asyncSplitGroups(source, getKey = value => value) {
  return __asyncSpliterateGrouped(source, asyncGroupingSpliterator, {
    getKey
  });
}

exports.__asyncSplitGroups = __asyncSplitGroups;
const asyncSplitGroups = /*#__PURE__*/asyncIterableCurry(__asyncSplitGroups, {
  minArgs: 0,
  maxArgs: 1
});
exports.asyncSplitGroups = asyncSplitGroups;