iterama/node/skip-async.js

Composable functional (async) iterable helpers

var _interopRequireDefault = require("@babel/runtime/helpers/interopRequireDefault");

Object.defineProperty(exports, "__esModule", {
  value: true
});
exports.skipAsync = void 0;

var _circularr = _interopRequireDefault(require("circularr"));

var _iterateAsync = require("./iterate-async");

const skipFirstAsync = n => iterable => ({
  async *[Symbol.asyncIterator]() {
    const asyncGenerator = (0, _iterateAsync.iterateAsync)(iterable);
    let i = 0;

    while (i < n) {
      const result = await asyncGenerator.next();

      if (result.done) {
        break;
      }

      i++;
    }

    for await (const value of asyncGenerator) {
      yield value;
    }
  }

});

const skipLastAsync = n => iterable => ({
  async *[Symbol.asyncIterator]() {
    const asyncGenerator = (0, _iterateAsync.iterateAsync)(iterable);
    const last = new _circularr.default(n);

    for (let i = 0; i < n; i++) {
      const result = await asyncGenerator.next();

      if (result.done) {
        break;
      }

      last.shift(result.value);
    }

    for await (const value of asyncGenerator) {
      yield last.shift(value);
    }
  }

});

const skipAsync = n => n < 0 ? skipLastAsync(-n) : skipFirstAsync(n);

exports.skipAsync = skipAsync;