Function reconcileChildrenIterator

dash/deps/react-dom@18.3.1.js:13721–13913

(returnFiber, currentFirstChild, newChildrenIterable, lanes)

    }

    function reconcileChildrenIterator(returnFiber, currentFirstChild, newChildrenIterable, lanes) {
      // This is the same implementation as reconcileChildrenArray(),
      // but using the iterator instead.
      var iteratorFn = getIteratorFn(newChildrenIterable);

      if (typeof iteratorFn !== 'function') {
        throw new Error('An object is not an iterable. This error is likely caused by a bug in ' + 'React. Please file an issue.');
      }

      {
        // We don't support rendering Generators because it's a mutation.
        // See https://github.com/facebook/react/issues/12995
        if (typeof Symbol === 'function' && // $FlowFixMe Flow doesn't know about toStringTag
        newChildrenIterable[Symbol.toStringTag] === 'Generator') {
          if (!didWarnAboutGenerators) {
            error('Using Generators as children is unsupported and will likely yield ' + 'unexpected results because enumerating a generator mutates it. ' + 'You may convert it to an array with `Array.from()` or the ' + '`[...spread]` operator before rendering. Keep in mind ' + 'you might need to polyfill these features for older browsers.');
          }

          didWarnAboutGenerators = true;
        } // Warn about using Maps as children


        if (newChildrenIterable.entries === iteratorFn) {
          if (!didWarnAboutMaps) {
            error('Using Maps as children is not supported. ' + 'Use an array of keyed ReactElements instead.');
          }

          didWarnAboutMaps = true;
        } // First, validate keys.
        // We'll get a different iterator later for the main pass.


        var _newChildren = iteratorFn.call(newChildrenIterable);

        if (_newChildren) {
          var knownKeys = null;

          var _step = _newChildren.next();

          for (; !_step.done; _step = _newChildren.next()) {
            var child = _step.value;
            knownKeys = warnOnInvalidKey(child, knownKeys, returnFiber);
          }
        }
      }

      var newChildren = iteratorFn.call(newChildrenIterable);

      if (newChildren == null) {
        throw new Error('An iterable object provided no iterator.');
      }

      var resultingFirstChild = null;
      var previousNewFiber = null;
      var oldFiber = currentFirstChild;
      var lastPlacedIndex = 0;
      var newIdx = 0;
      var nextOldFiber = null;