Add List.insert.

runtime/lib/growable_array.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.
 
 class _GrowableObjectArray<T> implements List<T> {
   factory _GrowableObjectArray._uninstantiable() {
     throw new UnsupportedError(
         "GrowableObjectArray can only be allocated by the VM");
   }
 
+  void insertAt(int index, T element) {
+    if (index is! int) throw new ArgumentError(index);

[srdjan, 2013/03/04 00:53:47]

Per Lars's instructions no explicit type checks should be added. Please remove
line above.

[floitsch, 2013/03/05 17:51:58]

Done.

+    if (index < 0 || index > length) throw new RangeError(index);

[Lasse Reichstein Nielsen, 2013/03/04 09:06:02]

Consider special-casing index == length into 'add'.

[floitsch, 2013/03/05 17:51:58]

Done.

+    int newLength = this.length + 1;
+    this.length = newLength;

[srdjan, 2013/03/04 00:53:47]

Why not just 'this.length+= 1;'?

[Lasse Reichstein Nielsen, 2013/03/04 09:06:02]

Remember oldLength instead. It seems it's what you need below. Or just remember
the number of elements after the index.

[floitsch, 2013/03/05 17:51:58]

Done.

+    Arrays.copy(this,
+                index,
+                this,
+                index + 1,
+                newLength - index - 1);
+    this[index] = element;
+  }
+
   T removeAt(int index) {
     if (index is! int) throw new ArgumentError(index);
     T result = this[index];
     int newLength = this.length - 1;
     Arrays.copy(this,
                 index + 1,
                 this,
                 index,
                 newLength - index);
     this.length = newLength;
@@ skipping 300 matching lines @@
   }
 
   List<T> toList({ bool growable: false }) {
     return new List<T>.from(this, growable: growable);
   }
 
   Set<T> toSet() {
     return new Set<T>.from(this);
   }
 }