Allow Object when doing lookups.

sdk/lib/collection/iterable.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.collection;
 
 /**
  * This [Iterable] mixin implements all [Iterable] members except `iterator`.
  *
  * All other methods are implemented in terms of `iterator`.
  */
 abstract class IterableMixin<E> implements Iterable<E> {
   Iterable map(f(E element)) => new MappedIterable<E, dynamic>(this, f);
 
   Iterable<E> where(bool f(E element)) => new WhereIterable<E>(this, f);
 
   Iterable expand(Iterable f(E element)) =>
       new ExpandIterable<E, dynamic>(this, f);
 
-  bool contains(E element) {
+  bool contains(Object element) {
     for (E e in this) {
       if (e == element) return true;
     }
     return false;
   }
 
   void forEach(void f(E element)) {
     for (E element in this) f(element);
   }
 
@@ skipping 103 matching lines @@
   }
 
   E get single {
     Iterator it = iterator;
     if (!it.moveNext()) throw new StateError("No elements");
     E result = it.current;
     if (it.moveNext()) throw new StateError("More than one element");
     return result;
   }
 
-  E firstWhere(bool test(E value), { E orElse() }) {
-    // TODO(floitsch): check that arguments are of correct type?
+  dynamic firstWhere(bool test(E value), { Object orElse() }) {
     for (E element in this) {
       if (test(element)) return element;
     }
     if (orElse != null) return orElse();
     throw new StateError("No matching element");
   }
 
-  E lastWhere(bool test(E value), {E orElse()}) {
-    // TODO(floitsch): check that arguments are of correct type?
+  dynamic lastWhere(bool test(E value), { Object orElse() }) {
     E result = null;
     bool foundMatching = false;
     for (E element in this) {
       if (test(element)) {
         result = element;
         foundMatching = true;
       }
     }
     if (foundMatching) return result;
     if (orElse != null) return orElse();
     throw new StateError("No matching element");
   }
 
   E singleWhere(bool test(E value)) {
-    // TODO(floitsch): check that argument is of correct type?
     E result = null;
     bool foundMatching = false;
     for (E element in this) {
       if (test(element)) {
         if (foundMatching) {
           throw new StateError("More than one matching element");
         }
         result = element;
         foundMatching = true;
       }
@@ skipping 24 matching lines @@
   // to combine const constructors and mixins.
   const IterableBase();
 
   Iterable map(f(E element)) => new MappedIterable<E, dynamic>(this, f);
 
   Iterable<E> where(bool f(E element)) => new WhereIterable<E>(this, f);
 
   Iterable expand(Iterable f(E element)) =>
       new ExpandIterable<E, dynamic>(this, f);
 
-  bool contains(E element) {
+  bool contains(Object element) {
     for (E e in this) {
       if (e == element) return true;
     }
     return false;
   }
 
   void forEach(void f(E element)) {
     for (E element in this) f(element);
   }
 
@@ skipping 103 matching lines @@
   }
 
   E get single {
     Iterator it = iterator;
     if (!it.moveNext()) throw new StateError("No elements");
     E result = it.current;
     if (it.moveNext()) throw new StateError("More than one element");
     return result;
   }
 
-  E firstWhere(bool test(E value), { E orElse() }) {
-    // TODO(floitsch): check that arguments are of correct type?
+  dynamic firstWhere(bool test(E value), { Object orElse() }) {
     for (E element in this) {
       if (test(element)) return element;
     }
     if (orElse != null) return orElse();
     throw new StateError("No matching element");
   }
 
-  E lastWhere(bool test(E value), {E orElse()}) {
-    // TODO(floitsch): check that arguments are of correct type?
+  dynamic lastWhere(bool test(E value), { Object orElse() }) {
     E result = null;
     bool foundMatching = false;
     for (E element in this) {
       if (test(element)) {
         result = element;
         foundMatching = true;
       }
     }
     if (foundMatching) return result;
     if (orElse != null) return orElse();
     throw new StateError("No matching element");
   }
 
   E singleWhere(bool test(E value)) {
-    // TODO(floitsch): check that argument is of correct type?
     E result = null;
     bool foundMatching = false;
     for (E element in this) {
       if (test(element)) {
         if (foundMatching) {
           throw new StateError("More than one matching element");
         }
         result = element;
         foundMatching = true;
       }
     }
     if (foundMatching) return result;
     throw new StateError("No matching element");
   }
 
   E elementAt(int index) {
     if (index is! int || index < 0) throw new RangeError.value(index);
     int remaining = index;
     for (E element in this) {
       if (remaining == 0) return element;
       remaining--;
     }
     throw new RangeError.value(index);
   }
 }