iterama/web/take-async.js

Composable functional (async) iterable helpers

import _defineProperty from "@babel/runtime/helpers/esm/defineProperty";
import _awaitAsyncGenerator from "@babel/runtime/helpers/esm/awaitAsyncGenerator";
import _wrapAsyncGenerator from "@babel/runtime/helpers/esm/wrapAsyncGenerator";
import _asyncIterator from "@babel/runtime/helpers/esm/asyncIterator";

function _createForOfIteratorHelper(o, allowArrayLike) { var it; if (typeof Symbol === "undefined" || o[Symbol.iterator] == null) { if (Array.isArray(o) || (it = _unsupportedIterableToArray(o)) || allowArrayLike && o && typeof o.length === "number") { if (it) o = it; var i = 0; var F = function F() {}; return { s: F, n: function n() { if (i >= o.length) return { done: true }; return { done: false, value: o[i++] }; }, e: function e(_e) { throw _e; }, f: F }; } throw new TypeError("Invalid attempt to iterate non-iterable instance.\nIn order to be iterable, non-array objects must have a [Symbol.iterator]() method."); } var normalCompletion = true, didErr = false, err; return { s: function s() { it = o[Symbol.iterator](); }, n: function n() { var step = it.next(); normalCompletion = step.done; return step; }, e: function e(_e2) { didErr = true; err = _e2; }, f: function f() { try { if (!normalCompletion && it.return != null) it.return(); } finally { if (didErr) throw err; } } }; }

function _unsupportedIterableToArray(o, minLen) { if (!o) return; if (typeof o === "string") return _arrayLikeToArray(o, minLen); var n = Object.prototype.toString.call(o).slice(8, -1); if (n === "Object" && o.constructor) n = o.constructor.name; if (n === "Map" || n === "Set") return Array.from(o); if (n === "Arguments" || /^(?:Ui|I)nt(?:8|16|32)(?:Clamped)?Array$/.test(n)) return _arrayLikeToArray(o, minLen); }

function _arrayLikeToArray(arr, len) { if (len == null || len > arr.length) len = arr.length; for (var i = 0, arr2 = new Array(len); i < len; i++) { arr2[i] = arr[i]; } return arr2; }

import FixedArray from 'circularr';
import { iterate } from './iterate';

var takeFirstAsync = function takeFirstAsync(n) {
  return function (iterable) {
    return _defineProperty({}, Symbol.asyncIterator, function () {
      return _wrapAsyncGenerator(function* () {
        if (n <= 0) {
          return;
        }

        var i = 0;
        var _iteratorNormalCompletion = true;
        var _didIteratorError = false;

        var _iteratorError;

        try {
          for (var _iterator = _asyncIterator(iterable), _step, _value; _step = yield _awaitAsyncGenerator(_iterator.next()), _iteratorNormalCompletion = _step.done, _value = yield _awaitAsyncGenerator(_step.value), !_iteratorNormalCompletion; _iteratorNormalCompletion = true) {
            var value = _value;
            yield value;

            if (++i >= n) {
              break;
            }
          }
        } catch (err) {
          _didIteratorError = true;
          _iteratorError = err;
        } finally {
          try {
            if (!_iteratorNormalCompletion && _iterator.return != null) {
              yield _awaitAsyncGenerator(_iterator.return());
            }
          } finally {
            if (_didIteratorError) {
              throw _iteratorError;
            }
          }
        }
      })();
    });
  };
};

var takeLastAsync = function takeLastAsync(n) {
  return function (iterable) {
    return _defineProperty({}, Symbol.asyncIterator, function () {
      return _wrapAsyncGenerator(function* () {
        var last = new FixedArray(n);
        var numValues = 0;
        var _iteratorNormalCompletion2 = true;
        var _didIteratorError2 = false;

        var _iteratorError2;

        try {
          for (var _iterator2 = _asyncIterator(iterable), _step2, _value2; _step2 = yield _awaitAsyncGenerator(_iterator2.next()), _iteratorNormalCompletion2 = _step2.done, _value2 = yield _awaitAsyncGenerator(_step2.value), !_iteratorNormalCompletion2; _iteratorNormalCompletion2 = true) {
            var value = _value2;
            last.shift(value);
            numValues++;
          }
          /* skip empty values */

        } catch (err) {
          _didIteratorError2 = true;
          _iteratorError2 = err;
        } finally {
          try {
            if (!_iteratorNormalCompletion2 && _iterator2.return != null) {
              yield _awaitAsyncGenerator(_iterator2.return());
            }
          } finally {
            if (_didIteratorError2) {
              throw _iteratorError2;
            }
          }
        }

        var iterator = iterate(last);
        var offset = last.length - numValues;

        for (var i = 0; i < offset; i++) {
          iterator.next();
        }
        /* actual values */


        var _iterator3 = _createForOfIteratorHelper(iterator),
            _step3;

        try {
          for (_iterator3.s(); !(_step3 = _iterator3.n()).done;) {
            var _value3 = _step3.value;
            yield _value3;
          }
        } catch (err) {
          _iterator3.e(err);
        } finally {
          _iterator3.f();
        }
      })();
    });
  };
};

export var takeAsync = function takeAsync(n) {
  return n < 0 ? takeLastAsync(-n) : takeFirstAsync(n);
};
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