function equalsIterable()

in packages/fbjs/src/functional/equalsIterable.js [19:50]

• 27 lines of code
• 10 McCabe index (conditional complexity)

function equalsIterable<T>(
  one: Iterable<T>,
  two: Iterable<T>,
  areEqual?: ?(one: T, two: T) => boolean,
): boolean {
  if (one === two) {
    return true;
  }

  // We might be able to short circuit by using the size or length fields.
  var oneSize = maybeGetSize(one);
  var twoSize = maybeGetSize(two);
  if (oneSize != null && twoSize != null && oneSize !== twoSize) {
    return false;
  }

  // Otherwise use the iterators to check equality. Here we cannot use for-of
  // because we need to advance the iterators at the same time.
  var oneIterator = enumerate(one);
  var oneItem = oneIterator.next();
  var twoIterator = enumerate(two);
  var twoItem = twoIterator.next();
  var safeAreEqual = areEqual || referenceEquality;
  while (!(oneItem.done || twoItem.done)) {
    if (!safeAreEqual(oneItem.value, twoItem.value)) {
      return false;
    }
    oneItem = oneIterator.next();
    twoItem = twoIterator.next();
  }
  return oneItem.done === twoItem.done;
}