"use strict";

exports.__esModule = true;
exports.default = arrayFrom;

/**
 * @source {https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/from#Polyfill}
 * but without thisArg (too hard to type, no need to `this`)
 */
var toStr = Object.prototype.toString;

function isCallable(fn) {
  return typeof fn === "function" || toStr.call(fn) === "[object Function]";
}

function toInteger(value) {
  var number = Number(value);

  if (isNaN(number)) {
    return 0;
  }

  if (number === 0 || !isFinite(number)) {
    return number;
  }

  return (number > 0 ? 1 : -1) * Math.floor(Math.abs(number));
}

var maxSafeInteger = Math.pow(2, 53) - 1;

function toLength(value) {
  var len = toInteger(value);
  return Math.min(Math.max(len, 0), maxSafeInteger);
}
/**
 * Creates an array from an iterable object.
 * @param iterable An iterable object to convert to an array.
 */


/**
 * Creates an array from an iterable object.
 * @param iterable An iterable object to convert to an array.
 * @param mapfn A mapping function to call on every element of the array.
 * @param thisArg Value of 'this' used to invoke the mapfn.
 */
function arrayFrom(arrayLike, mapFn) {
  // 1. Let C be the this value.
  // edit(@eps1lon): we're not calling it as Array.from
  var C = Array; // 2. Let items be ToObject(arrayLike).

  var items = Object(arrayLike); // 3. ReturnIfAbrupt(items).

  if (arrayLike == null) {
    throw new TypeError("Array.from requires an array-like object - not null or undefined");
  } // 4. If mapfn is undefined, then let mapping be false.
  // const mapFn = arguments.length > 1 ? arguments[1] : void undefined;


  if (typeof mapFn !== "undefined") {
    // 5. else
    // 5. a If IsCallable(mapfn) is false, throw a TypeError exception.
    if (!isCallable(mapFn)) {
      throw new TypeError("Array.from: when provided, the second argument must be a function");
    }
  } // 10. Let lenValue be Get(items, "length").
  // 11. Let len be ToLength(lenValue).


  var len = toLength(items.length); // 13. If IsConstructor(C) is true, then
  // 13. a. Let A be the result of calling the [[Construct]] internal method
  // of C with an argument list containing the single item len.
  // 14. a. Else, Let A be ArrayCreate(len).

  var A = isCallable(C) ? Object(new C(len)) : new Array(len); // 16. Let k be 0.

  var k = 0; // 17. Repeat, while k < len… (also steps a - h)

  var kValue;

  while (k < len) {
    kValue = items[k];

    if (mapFn) {
      A[k] = mapFn(kValue, k);
    } else {
      A[k] = kValue;
    }

    k += 1;
  } // 18. Let putStatus be Put(A, "length", len, true).


  A.length = len; // 20. Return A.

  return A;
}
//# sourceMappingURL=array.from.js.map