LibTest/collection/UnmodifiableMapBase/unmodifiablemapbase.lib.dart

// Copyright (c) 2017, 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.

/// @assertion UnmodifiableMapBase<K, V>
/// Basic implementation of an unmodifiable [Map].
/// This class has a basic implementation of all but two of the members of an
/// umodifiable [Map]. A simple unmodifiable [Map] class can be implemented by
/// extending this class and implementing [keys] and operator[].
/// @description Implementation of [simple UnmodifiableMapBase]
/// @author iarkh@unipro.ru

library unmodifiable_map_base_lib;
import "dart:collection";

class UnmodifiableMapBaseImpl<K, V> extends UnmodifiableMapBase<K, V> {
  LinkedHashMap<K, V> _map;

  UnmodifiableMapBaseImpl(Map content): _map =
      new LinkedHashMap<K, V>.from(content);

  Iterable<K> get keys => _map.keys;
  
  V? operator [](Object? key) => _map[key];
}