blob: 581532f605deb74c0c7ab359b1dc28eafbe3f86a [file] [log] [blame]
// Copyright (c) 2016, the Dart project authors. Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.
import 'dart:collection';
import 'unmodifiable_wrappers.dart';
// Unfortunately, we can't use UnmodifiableSetMixin here, since const classes
// can't use mixins.
/// An unmodifiable, empty set that can have a const constructor.
class EmptyUnmodifiableSet<E> extends IterableBase<E>
implements UnmodifiableSetView<E> {
static /*=T*/ _throw/*<T>*/() {
throw new UnsupportedError("Cannot modify an unmodifiable Set");
Iterator<E> get iterator => new Iterable<E>.empty().iterator;
int get length => 0;
const EmptyUnmodifiableSet();
bool contains(Object element) => false;
bool containsAll(Iterable<Object> other) => other.isEmpty;
E lookup(Object element) => null;
Set<E> toSet() => new Set();
Set<E> union(Set<E> other) => new Set.from(other);
Set<E> intersection(Set<Object> other) => new Set();
Set<E> difference(Set<Object> other) => new Set();
bool add(E value) => _throw();
void addAll(Iterable<E> elements) => _throw();
void clear() => _throw();
bool remove(Object element) => _throw();
void removeAll(Iterable<Object> elements) => _throw();
void removeWhere(bool test(E element)) => _throw();
void retainWhere(bool test(E element)) => _throw();
void retainAll(Iterable<Object> elements) => _throw();