Add unmodifiable_collection package.

pkg/unmodifiable_collection/lib/unmodifiable_collection.dart

+// Copyright (c) 2013, 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.
+
+/**
+ * Unmodifiable wrappers for [List], [Set] and [Map] objects.
+ *
+ * The wrappers allow reading from the source list, but writing is prohibited.
+ *
+ * A non-growable list wrapper allows writing as well, but not changing the
+ * list's length.
+ */
+library unmodifiable_collection;
+
+export "dart:collection" show UnmodifiableListView;
+
+/**
+ * A [List] wrapper that acts as a non-growable list.
+ *
+ * Writes to the list are written through to the source list, but operations
+ * that change the length is not allowed.
+ */
+class NonGrowableListView<E> extends _IterableView<E>
+                                     implements List<E> {
+  List<E> _source;
+  NonGrowableListView(List<E> source) : _source = source;
+
+  static void _throw() {
+    throw new UnsupportedError(
+        "Cannot change the length of a fixed-length list");
+  }
+
+  int get length => _source.length;
+
+  E operator [](int index) => _source[index];
+
+  int indexOf(E element, [int start = 0]) => _source.indexOf(element, start);
+
+  int lastIndexOf(E element, [int start])
+      => _source.lastIndexOf(element, start);
+
+  Iterable<E> getRange(int start, int end) => _source.getRange(start, end);
+
+  List<E> sublist(int start, [int end]) => _source.sublist(start, end);
+
+  Iterable<E> get reversed => _source.reversed;
+
+  Map<int, E> asMap() => _source.asMap();
+
+
+  void operator []=(int index, E value) { _source[index] = value; }
+
+  void sort([int compare(E a, E b)]) { _source.sort(compare); }
+
+  void setRange(int start, int end, Iterable<E> iterable, [int skipCount = 0]) {
+    _source.setRange(start, end, iterable, skipCount);
+  }
+
+  void fillRange(int start, int end, [E fillValue]) {
+    _source.fillRange(start, end, fillValue);
+  }
+
+  void setAll(int index, Iterable<E> iterable) {
+    _source.setAll(index, iterable);
+  }
+
+
+  void set length(int newLength) => _throw();
+
+  void add(E value) => _throw();
+
+  void addAll(Iterable<E> iterable) => _throw();
+
+  void insert(int index, E element) => _throw();
+
+  void insertAll(int index, Iterable<E> iterable) => _throw();
+
+  bool remove(Object value) { _throw(); }
+
+  E removeAt(int index) { _throw(); }
+
+  E removeLast() { _throw(); }
+
+  void removeWhere(bool test(E element)) => _throw();
+
+  void retainWhere(bool test(E element)) => _throw();
+
+  void removeRange(int start, int end) => _throw();
+
+  void replaceRange(int start, int end, Iterable<E> iterable) => _throw();
+
+  void clear() => _throw();
+}
+
+/**
+ * A [Set] wrapper that acts as an unmodifiable set.
+ */
+class UnmodifiableSetView<E> extends _IterableView<E>
+                                      implements Set<E> {
+  Set<E> _source;
+  UnmodifiableSetView(Set<E> source) : _source = source;
+
+  void _throw() {
+    throw new UnsupportedError("Cannot modify an unmodifiable Set");
+  }
+
+  bool containsAll(Iterable<E> other) => _source.containsAll(other);
+
+  Set<E> intersection(Set<E> other) => _source.intersection(other);
+
+  Set<E> union(Set<E> other) => _source.union(other);
+
+  Set<E> difference(Set<E> other) => _source.difference(other);
+
+
+  void add(E value) => _throw();
+
+  void addAll(Iterable<E> elements) => _throw();
+
+  bool remove(Object value) { _throw(); }
+
+  void removeAll(Iterable elements) => _throw();
+
+  void retainAll(Iterable elements) => _throw();
+
+  void removeWhere(bool test(E element)) => _throw();
+
+  void retainWhere(bool test(E element)) => _throw();
+
+  void clear() => _throw();
+}
+
+/**
+ * A [Map] wrapper that acts as an unmodifiable map.
+ */
+class UnmodifiableMapView<K, V> implements Map<K, V> {

[Søren Gjesse, 2013/07/31 12:33:08]

Could we consider having this in the dart:collection library like we already
have UnmodifiableListView? I already have this code in uri.dart (class
_UnmodifiableMap), so size-wise it should not be an issue. Currently I am adding
another copy to the dart:io library.

[ahe, 2013/08/07 15:57:59]

+1

I need it for dart:mirrors.

[floitsch, 2013/11/05 01:23:25]

I discussed this with Lasse, and we will probably merge the package into the
collection library.

+  Map<K, V> _source;
+  UnmodifiableMapView(Map<K, V> source) : _source = source;
+
+  static void _throw() {
+    throw new UnsupportedError("Cannot modify an unmodifiable Map");
+  }
+
+  int get length => _source.length;
+
+  bool get isEmpty => _source.isEmpty;
+
+  bool get isNotEmpty => _source.isNotEmpty;
+
+  V operator [](K key) => _source[key];
+
+  bool containsKey(K key) => _source.containsKey(key);
+
+  bool containsValue(V value) => _source.containsValue(value);
+
+  void forEach(void f(K key, V value)) => _source.forEach(f);
+
+  Iterable<K> get keys => _source.keys;
+
+  Iterable<V> get values => _source.values;
+
+
+  void operator []=(K key, V value) => _throw();
+
+  V putIfAbsent(K key, V ifAbsent()) { _throw(); }
+
+  void addAll(Map<K, V> other) => _throw();
+
+  V remove(K key) { _throw(); }
+
+  void clear() => _throw();
+}
+
+abstract class _IterableView<E> {
+  Iterable<E> get _source;
+
+  bool any(bool test(E element)) => _source.any(test);
+
+  bool contains(E element) => _source.contains(element);
+
+  E elementAt(int index) => _source.elementAt(index);
+
+  bool every(bool test(E element)) => _source.every(test);
+
+  Iterable expand(Iterable f(E element)) => _source.expand(f);
+
+  E get first => _source.first;
+
+  E firstWhere(bool test(E element), { E orElse() })
+      => _source.firstWhere(test, orElse: orElse);
+
+  dynamic fold(var initialValue,
+               dynamic combine(var previousValue, E element))
+      => _source.fold(initialValue, combine);
+
+  void forEach(void f(E element)) => _source.forEach(f);
+
+  bool get isEmpty => _source.isEmpty;
+
+  bool get isNotEmpty => _source.isNotEmpty;
+
+  Iterator<E> get iterator => _source.iterator;
+
+  String join([String separator = ""]) => _source.join(separator);
+
+  E get last => _source.last;
+
+  E lastWhere(bool test(E element), {E orElse()})
+      => _source.lastWhere(test, orElse: orElse);
+
+  int get length => _source.length;
+
+  Iterable map(f(E element)) => _source.map(f);
+
+  E reduce(E combine(E value, E element)) => _source.reduce(combine);
+
+  E get single => _source.single;
+
+  E singleWhere(bool test(E element)) => _source.singleWhere(test);
+
+  Iterable<E> skip(int n) => _source.skip(n);
+
+  Iterable<E> skipWhile(bool test(E value)) => _source.skipWhile(test);
+
+  Iterable<E> take(int n) => _source.take(n);
+
+  Iterable<E> takeWhile(bool test(E value)) => _source.takeWhile(test);
+
+  List<E> toList({ bool growable: true }) => _source.toList(growable: growable);
+
+  Set<E> toSet() => _source.toSet();
+
+  Iterable<E> where(bool test(E element)) => _source.where(test);
+}