Refactor List.setRange function.

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;
 
 /**
  * This class provides default implementations for Iterables (including Lists).
  *
  * Once Dart receives Mixins it will be replaced with mixin classes.
@@ skipping 251 matching lines @@
     if (start < 0 || start > list.length) {
       throw new RangeError.range(start, 0, list.length);
     }
     if (end < start || end > list.length) {
       throw new RangeError.range(end, start, list.length);
     }
     // The generic type is currently lost. It will be fixed with mixins.
     return new SubListIterable(list, start, end);
   }
 
-  static void setRangeList(List list, int start, int length,
-                           List from, int startFrom) {
+  static void setRangeList(List list, int start, int end,
+                           Iterable from, int skipCount) {
+    if (start < 0 || start > list.length) {
+      throw new RangeError.range(start, 0, list.length);
+    }
+    if (end < start || end > list.length) {
+      throw new RangeError.range(end, start, list.length);
+    }
+    int length = end - start;
     if (length == 0) return;
 
-    if (length < 0) throw new ArgumentError(length);
-    if (start < 0) throw new RangeError.value(start);
-    if (start + length > list.length) {
-      throw new RangeError.value(start + length);
+    if (skipCount < 0) throw new ArgumentError(skipCount);
+
+    // TODO(floitsch): Make this accept more.
+    List otherList;
+    int otherStart;
+    if (from is List) {
+      otherList = from;
+      otherStart = skipCount;
+    } else {
+      otherList = from.skip(skipCount).toList(growable: false);
+      otherStart = 0;
     }
-
-    Arrays.copy(from, startFrom, list, start, length);
+    if (otherStart + length > otherList.length) {
+      throw new StateError("Not enough elements");
+    }
+    Arrays.copy(otherList, otherStart, list, start, length);
   }
 
   static Map<int, dynamic> asMapList(List l) {
     return new ListMapView(l);
   }
 
   static bool setContainsAll(Set set, Iterable other) {
     for (var element in other) {
       if (!set.contains(element)) return false;
     }
@@ skipping 40 matching lines @@
  * The source of the elements may be a [List] or any [Iterable] with
  * efficient [Iterable.length] and [Iterable.elementAt].
  */
 class UnmodifiableListView<E> extends UnmodifiableListBase<E> {
   Iterable<E> _source;
   /** Create an unmodifiable list backed by [source]. */
   UnmodifiableListView(Iterable<E> source) : _source = source;
   int get length => _source.length;
   E operator[](int index) => _source.elementAt(index);
 }