insertAll method Null safety

void insertAll(
  1. Iterable<OverlayEntry> entries,
  2. {OverlayEntry? below,
  3. OverlayEntry? above}
)

Insert all the entries in the given iterable.

If below is non-null, the entries are inserted just below below. If above is non-null, the entries are inserted just above above. Otherwise, the entries are inserted on top.

It is an error to specify both above and below.

Implementation

void insertAll(Iterable<OverlayEntry> entries, { OverlayEntry? below, OverlayEntry? above }) {
  assert(_debugVerifyInsertPosition(above, below));
  assert(
    entries.every((OverlayEntry entry) => !_entries.contains(entry)),
    'One or more of the specified entries are already present in the Overlay.',
  );
  assert(
    entries.every((OverlayEntry entry) => entry._overlay == null),
    'One or more of the specified entries are already present in another Overlay.',
  );
  if (entries.isEmpty) {
    return;
  }
  for (final OverlayEntry entry in entries) {
    assert(entry._overlay == null);
    entry._overlay = this;
  }
  setState(() {
    _entries.insertAll(_insertionIndex(below, above), entries);
  });
}