Unify error messages for iterables and lists.

sdk/lib/internal/list.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.
 
 part of dart._internal;
 
 /**
  * Mixin that throws on the length changing operations of [List].
  *
  * Intended to mix-in on top of [ListMixin] for fixed-length lists.
@@ skipping 289 matching lines @@
 class ReversedListIterable<E> extends ListIterable<E> {
   Iterable<E> _source;
   ReversedListIterable(this._source);
 
   int get length => _source.length;
 
   E elementAt(int index) => _source.elementAt(_source.length - 1 - index);
 }
 
 /**
+ * Creates errors thrown by unmodifiable lists when they are attempted modified.
+ *
+ * This class creates [UnsupportedError]s with specialized messages.
+ */
+abstract class UnmodifiableListError {
+  /** Error thrown when trying to add elements to an unmodifiable list. */
+  static UnsupportedError add()
+      => new UnsupportedError("Cannot add to unmodifiable List");
+
+  /** Error thrown when trying to add elements to an unmodifiable list. */
+  static UnsupportedError change()
+      => new UnsupportedError(
+             "Cannot change the content of an unmodifiable List");
+
+  /** Error thrown when trying to change the length of an unmodifiable list. */
+  static UnsupportedError length()
+      => new UnsupportedError("Cannot change length of unmodifiable List");
+
+  /** Error thrown when trying to remove elements from an unmodifiable list. */
+  static UnsupportedError remove()
+      => new UnsupportedError("Cannot remove from unmodifiable List");
+}
+
+/**
+ * Creates errors thrown by non-growable lists when they are attempted modified.
+ *
+ * This class creates [UnsupportedError]s with specialized messages.
+ */
+abstract class NonGrowableListError {
+  /** Error thrown when trying to add elements to an non-growable list. */
+  static UnsupportedError add()
+      => new UnsupportedError("Cannot add to non-growable List");
+
+  /** Error thrown when trying to change the length of an non-growable list. */
+  static UnsupportedError length()
+      => new UnsupportedError("Cannot change length of non-growable List");
+
+  /** Error thrown when trying to remove elements from an non-growable list. */
+  static UnsupportedError remove()
+      => new UnsupportedError("Cannot remove from non-growable List");
+}
+
+/**
  * Converts a growable list to a fixed length list with the same elements.
  *
  * For internal use only.
  * Only works on growable lists as created by `[]` or `new List()`.
  * May throw on any other list.
  *
  * The operation is efficient. It doesn't copy the elements, but converts
  * the existing list directly to a fixed length list.
  * That means that it is a destructive conversion.
  * The original list should not be used afterwards.
  *
  * The returned list may be the same list as the orginal,
  * or it may be a different list (according to [identical]).
  * The original list may have changed type to be a fixed list,
  * or become empty or been otherwise modified.
  * It will still be a valid object, so references to it will not, e.g., crash
  * the runtime if accessed, but no promises are made wrt. its contents.
  *
  * This unspecified behavior is the reason the function is not exposed to
  * users. We allow the underlying implementation to make the most efficient
  * conversion, at the cost of leaving the original list in an unspecified
  * state.
  */
 external List makeListFixedLength(List growableList);