readmongo/node_modules/core-js/internals/iterate.js

var anObject = require('../internals/an-object');
var isArrayIteratorMethod = require('../internals/is-array-iterator-method');
var toLength = require('../internals/to-length');
var bind = require('../internals/function-bind-context');
var getIteratorMethod = require('../internals/get-iterator-method');
var iteratorClose = require('../internals/iterator-close');

var Result = function (stopped, result) {
  this.stopped = stopped;
  this.result = result;
};

module.exports = function (iterable, unboundFunction, options) {
  var that = options && options.that;
  var AS_ENTRIES = !!(options && options.AS_ENTRIES);
  var IS_ITERATOR = !!(options && options.IS_ITERATOR);
  var INTERRUPTED = !!(options && options.INTERRUPTED);
  var fn = bind(unboundFunction, that, 1 + AS_ENTRIES + INTERRUPTED);
  var iterator, iterFn, index, length, result, next, step;

  var stop = function (condition) {
    if (iterator) iteratorClose(iterator);
    return new Result(true, condition);
  };

  var callFn = function (value) {
    if (AS_ENTRIES) {
      anObject(value);
      return INTERRUPTED ? fn(value[0], value[1], stop) : fn(value[0], value[1]);
    } return INTERRUPTED ? fn(value, stop) : fn(value);
  };

  if (IS_ITERATOR) {
    iterator = iterable;
  } else {
    iterFn = getIteratorMethod(iterable);
    if (typeof iterFn != 'function') throw TypeError('Target is not iterable');
    // optimisation for array iterators
    if (isArrayIteratorMethod(iterFn)) {
      for (index = 0, length = toLength(iterable.length); length > index; index++) {
        result = callFn(iterable[index]);
        if (result && result instanceof Result) return result;
      } return new Result(false);
    }
    iterator = iterFn.call(iterable);
  }

  next = iterator.next;
  while (!(step = next.call(iterator)).done) {
    try {
      result = callFn(step.value);
    } catch (error) {
      iteratorClose(iterator);
      throw error;
    }
    if (typeof result == 'object' && result && result instanceof Result) return result;
  } return new Result(false);
};