MultiViewList<E> is a lightweight wrapper around a Dart list that exposes the same read/write behaviour but allows multiple views to share the same underlying storage. It converts any Iterable<E> into a list on construction and provides an unmodifiable view when needed. The primary goal is to support the ordered‑map keys lists used by OrderedMap and to allow slicing and filtering operations to return new MultiViewList instances without copying the entire list.
MultiViewList<E>({ required Iterable<E> source })
source – any iterable of elements. If it is already a List<E> then it is used directly; otherwise the iterable is eagerly collected into a new list. The resulting list backs all view operations.Internally the class stores:
source – the original iterable (for reference)._listSource – the backing list.unmodifiable – an UnmodifiableListView<E> pointing at _listSource for read‑only access.MultiViewList implements Iterable<E>, so you can iterate over it directly. It provides:
length – the number of elements.isEmpty / isNotEmpty – whether the list has zero elements.iterator – returns _listSource.iterator.forEach(void Function(E element) action) – applies a function to each element.first, last, single – get specific elements (throws if conditions aren’t met).operator [] and elementAt(int) – return the element at a given index.indexOf(element, [int start]) – search for the element starting at start.firstWhere, lastWhere, singleWhere – search with a predicate, optionally supplying an orElse callback.any / every / contains – standard Dart list checks.Although most of dartora’s collection types are immutable views, MultiViewList is mutable. You can:
set(int index, E value) – replace the element at the given index.add(E value) – append to the end of the list.remove(Object? value) – remove the first occurrence (returns a boolean indicating success).removeAt(int index) – remove the element at the index and return it.clear() – remove all elements.Standard reduction methods from Iterable are delegated to the backing list:
join([separator]) – join elements into a string.reduce(combine) – reduce using a binary function.fold(initial, combine) – fold with an initial value.View‑oriented methods return new MultiViewList instances wrapping a transformed List:
map(toElement) – lazily applies a function to each element, returning a new MultiViewList of the mapped type.followedBy(other) – returns a new view that concatenates this list with another iterable.expand(toElements) – expands each element into zero or more values.skip(count) / take(count) – skip or take a prefix of elements.skipWhile(test) / takeWhile(test) – skip/take based on a predicate.where(test) – filter by predicate.whereType<T>() – keep only elements of a given type.cast<R>() – cast elements to a different type (performs no checks).toList({bool growable = true}) – returns a copy of the backing list (read‑only by default).toSet() – returns a Set of the elements.MultiViewList is intentionally simple: it is mostly a façade over List that returns new MultiViewList instances when an operation would otherwise return a plain list. This preserves the ability for OrderedMap and ChildHolder to build multiple views without reallocating memory.