Add min and max to Iterable and Stream.

sdk/lib/collection/collections.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;
 
 /**
  * The [Collections] class implements static methods useful when
  * writing a class that implements [Collection] and the [iterator]
  * method.
@@ skipping 52 matching lines @@
     if (!it.moveNext()) {
       throw new StateError("No elements");
     }
     dynamic result;
     do {
       result = it.current;
     } while(it.moveNext());
     return result;
   }
 
+  static dynamic min(Iterable iterable, [int compare(var a, var b)]) {
+    if (compare == null) compare = Comparable.compare;
+    Iterator it = iterable.iterator;
+    if (!it.moveNext()) {
+      return null;

[Anders Johnsen, 2013/01/02 11:04:05]

State error? [].min() -> null?

[Lasse Reichstein Nielsen, 2013/01/02 11:49:33]

It's deliberate. We can argue whether it's the right thing to do :).
What I *really* would want is the interface:
  min([int compare(a,b)], {var ifEmpty})
but until we get both optional positional and named arguments, I'll just default
to null.

+    }
+    var min = it.current;
+    while (it.moveNext()) {
+      if (compare(min, it.current) > 0) min = it.current;
+    }
+    return min;
+  }
+
+  static dynamic max(Iterable iterable, [int compare(var a, var b)]) {
+    if (compare == null) compare = Comparable.compare;
+    Iterator it = iterable.iterator;
+    if (!it.moveNext()) {
+      return null;
+    }
+    var max = it.current;
+    while (it.moveNext()) {
+      if (compare(max, it.current) < 0) max = it.current;
+    }
+    return max;
+  }
+
   static dynamic single(Iterable iterable) {
     Iterator it = iterable.iterator;
     if (!it.moveNext()) throw new StateError("No elements");
     dynamic result = it.current;
     if (it.moveNext()) throw new StateError("More than one element");
     return result;
   }
 
   static dynamic firstMatching(Iterable iterable,
                                bool test(dynamic value),
@@ skipping 188 matching lines @@
    * Returns true if the specified collection contains the specified object
    * reference.
    */
   static _containsRef(Collection c, Object ref) {
     for (var e in c) {
       if (identical(e, ref)) return true;
     }
     return false;
   }
 }