Add List.reversed to give a reverse fixed-length view of a list.

sdk/lib/core/errors.dart

 // Copyright (c) 2012, 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.core;
 
 class Error {
   const Error();
 
   /**
@@ skipping 75 matching lines @@
   /**
    * Create a new [RangeError] with the given [message].
    *
    * Temporarily made const for backwards compatibilty.
    */
   RangeError(var message) : super(message);
 
   /** Create a new [RangeError] with a message for the given [value]. */
   RangeError.value(num value) : super("value $value");
 
+  /** Create a new [RangeError] with a message for a value and a range. */
+  RangeError.range(num value, num start, num end)
+      : super("value $value not in range $start..$end");
+
   String toString() => "RangeError: $message";
 }
 
 
 /**
  * Error thrown when control reaches the end of a switch case.
  *
  * The Dart specification requires this error to be thrown when
  * control reaches the end of a switch case (except the last case
  * of a switch) without meeting a break or similar end of the control
@@ skipping 125 matching lines @@
  * This is a generic error used for a variety of different erroneous
  * actions. The message should be descriptive.
  */
 class StateError implements Error {
   final String message;
   StateError(this.message);
   String toString() => "Bad state: $message";
 }
 
 
+/**
+ * Error occurring when a collection is modified during iteration.
+ *
+ * Some modifications may be allowed for some collections, so each collection
+ * ([Iterable] or similar collection of values) should declare which operations
+ * are allowed during an iteration.
+ */
+class ConcurrentModificationError implements Error {
+  /** The object that was modified in an incompatible way. */
+  final Object modifiedObject;
+
+  const ConcurrentModificationError([this.modifiedObject]);
+
+  String toString() {
+    if (modifiedObject == null) {
+      return "Concurrent modification during iteration.";
+    }
+    return "Concurrent modification during iteration: "
+           "${Error.safeToString(modifiedObject)}.";
+  }
+}
+
+
 class OutOfMemoryError implements Error {
   const OutOfMemoryError();
   String toString() => "Out of Memory";
 }
 
 class StackOverflowError implements Error {
   const StackOverflowError();
   String toString() => "Stack Overflow";
 }
 
 /**
  * Error thrown when a runtime error occurs.
  */
 class RuntimeError implements Error {
   final message;
   RuntimeError(this.message);
   String toString() => "RuntimeError: $message";
 }