Add min and max to Iterable and Stream.

sdk/lib/core/iterable.dart

 // Copyright (c) 2011, 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;
 
 /**
  * The [Iterable] interface allows to get an [Iterator] out of an
  * [Iterable] object.
  *
@@ skipping 130 matching lines @@
   int get length {
     int count = 0;
     Iterator it = iterator;
     while (it.moveNext()) {
       count++;
     }
     return count;
   }
 
   /**
+   * Find the least element in the iterable.
+   *
+   * Returns null if the iterable is empty.
+   * Otherwise returns an element [:x:] of this [Iterable] so that
+   * [:x:] is not greater than [:y:] (that is, [:compare(x, y) <= 0:]) for all
+   * other elements [:y:] in the iterable.
+   *
+   * The [compare] function must be a proper [Comparator<T>]. If a function is
+   * not provided, [compare] defaults to [Comparable.compare].
+   */
+  T min([int compare(T a, T b)]) {
+    if (compare == null) compare = Comparable.compare;
+    Iterator it = iterator;
+    if (!it.moveNext()) return null;
+    T min = it.current;
+    while (it.moveNext) {
+      T current = it.current;
+      if (compare(min, current) > 0) min = current;
+    }
+    return min;
+  }
+
+  /**
+   * Find the largest element in the iterable.
+   *
+   * Returns null if the iterable is empty.
+   * Otherwise returns an element [:x:] of this [Iterable] so that
+   * [:x:] is not smaller than [:y:] (that is, [:compare(x, y) >= 0:]) for all
+   * other elements [:y:] in the iterable.
+   *
+   * The [compare] function must be a proper [Comparator<T>]. If a function is
+   * not provided, [compare] defaults to [Comparable.compare].
+   */
+  T max([int compare(T a, T b)]) {
+    if (compare == null) compare = Comparable.compare;
+    Iterator it = iterator;
+    if (!it.moveNext()) return null;
+    T max = it.current;
+    while (it.moveNext) {
+      T current = it.current;
+      if (compare(max, current) < 0) max = current;
+    }
+    return max;
+  }
+
+  /**
    * Returns true if there is no element in this collection.
    */
   bool get isEmpty => !iterator.moveNext();
 
   /**
    * Returns an [Iterable] with at most [n] elements.
    *
    * The returned [Iterable] may contain fewer than [n] elements, if [this]
    * contains fewer than [n] elements.
    */
@@ skipping 358 matching lines @@
       _hasSkipped = true;
       while (_iterator.moveNext()) {
         if (!_f(_iterator.current)) return true;
       }
     }
     return _iterator.moveNext();
   }
 
   E get current => _iterator.current;
 }