Allow Object when doing lookups.

sdk/lib/collection/splay_tree.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;
 
 /**
  * A node in a splay tree. It holds the sorting key and the left
  * and right children in the tree.
  */
@@ skipping 237 matching lines @@
   SplayTreeMap([int compare(K key1, K key2)])
       : _comparator = (compare == null) ? Comparable.compare : compare;
 
   factory SplayTreeMap.from(Map<K, V> other, [int compare(K key1, K key2)]) =>
       new SplayTreeMap(compare)..addAll(other);
 
   int _compare(K key1, K key2) => _comparator(key1, key2);
 
   SplayTreeMap._internal();
 
-  V operator [](K key) {
+  V operator [](Object key) {
     if (key == null) throw new ArgumentError(key);
+    if (key is! K) return null;

[Lasse Reichstein Nielsen, 2013/06/18 14:13:08]

Per earlier discussion, could we keep this as "K"?
A TreeMap<K,V> is not really castable to any TreeMap<K2,V> with K superlass of
K.

[floitsch, 2013/06/20 15:52:50]

As discussed in person: leaving as is.

     if (_root != null) {
       int comp = _splay(key);
       if (comp == 0) {
         _SplayTreeMapNode mapRoot = _root;
         return mapRoot.value;
       }
     }
     return null;
   }
 
@@ skipping 60 matching lines @@
   }
 
   int get length {
     return _count;
   }
 
   void clear() {
     _clear();
   }
 
-  bool containsKey(K key) {
-    return _splay(key) == 0;
+  bool containsKey(Object key) {
+    return key is K && _splay(key) == 0;
   }
 
-  bool containsValue(V value) {
+  bool containsValue(Object value) {
     bool found = false;
     int initialSplayCount = _splayCount;
     bool visit(_SplayTreeMapNode node) {
       while (node != null) {
         if (node.value == value) return true;
         if (initialSplayCount != _splayCount) {
           throw new ConcurrentModificationError(this);
         }
         if (node.right != null && visit(node.right)) return true;
         node = node.left;
@@ skipping 181 matching lines @@
 class _SplayTreeValueIterator<K, V> extends _SplayTreeIterator<V> {
   _SplayTreeValueIterator(SplayTreeMap<K, V> map): super(map);
   V _getValue(_SplayTreeMapNode node) => node.value;
 }
 
 class _SplayTreeNodeIterator<K>
     extends _SplayTreeIterator<_SplayTreeNode<K>> {
   _SplayTreeNodeIterator(_SplayTree<K> map): super(map);
   _SplayTreeNode<K> _getValue(_SplayTreeNode node) => node;
 }