Jonas Termansen
80621fed03
Change-Id: I44047a9d7907d166a6360397d0047ce9b835e5c7 Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/166854 Auto-Submit: Jonas Termansen <sortie@google.com> Reviewed-by: Leaf Petersen <leafp@google.com> Commit-Queue: Leaf Petersen <leafp@google.com>
27 lines
928 B
Dart
27 lines
928 B
Dart
/// Marker interface for [Iterable] subclasses that have an efficient
|
|
/// [length] implementation.
|
|
|
|
// @dart=2.9
|
|
|
|
abstract class EfficientLengthIterable<T> extends Iterable<T> {
|
|
const EfficientLengthIterable();
|
|
|
|
/// Returns the number of elements in the iterable.
|
|
///
|
|
/// This is an efficient operation that doesn't require iterating through
|
|
/// the elements.
|
|
int get length;
|
|
}
|
|
|
|
/// Creates errors throw by [Iterable] when the element count is wrong.
|
|
abstract class IterableElementError {
|
|
/// Error thrown thrown by, e.g., [Iterable.first] when there is no result.
|
|
static StateError noElement() => StateError("No element");
|
|
|
|
/// Error thrown by, e.g., [Iterable.single] if there are too many results.
|
|
static StateError tooMany() => StateError("Too many elements");
|
|
|
|
/// Error thrown by, e.g., [List.setRange] if there are too few elements.
|
|
static StateError tooFew() => StateError("Too few elements");
|
|
}
|