Optimize VM JSON parser for memory use.

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;
 
 /**
  * An object that uses an [Iterator] to serve objects one at a time.
  *
  * You can iterate over all objects served by an Iterable object
@@ skipping 26 matching lines @@
   /**
    * Creates an Iterable that generates its elements dynamically.
    *
    * The Iterators created by the Iterable count from
    * zero to [:count - 1:] while iterating, and call [generator]
    * with that index to create the next value.
    *
    * As an Iterable, [:new Iterable.generate(n, generator)):] is equivalent to
    * [:const [0, ..., n - 1].map(generator):]
    */
-  factory Iterable.generate(int count, E generator(int index)) {
-    return new _GeneratorIterable<E>(count, generator);
-  }
+  const factory Iterable.generate(int count, E generator(int index)) =
+    _GeneratorIterable<E>;
 
   /**
    * Returns an Iterator that iterates over this Iterable object.
    */
   Iterator<E> get iterator;
 
   /**
    * Returns a lazy [Iterable] where each element [:e:] of `this` is replaced
    * by the result of [:f(e):].
    *
@@ skipping 224 matching lines @@
    */
   E elementAt(int index);
 }
 
 typedef E _Generator<E>(int index);
 
 class _GeneratorIterable<E> extends IterableBase<E>
                             implements EfficientLength {
   final int _count;
   final _Generator<E> _generator;
-  _GeneratorIterable(this._count, this._generator);
+  const _GeneratorIterable(this._count, this._generator);
   Iterator<E> get iterator => new _GeneratorIterator(_count, _generator);
   int get length => _count;
 }
 
 class _GeneratorIterator<E> implements Iterator<E> {
   final int _count;
   final _Generator<E> _generator;
   int _index = 0;
   E _current;
 
@@ skipping 18 matching lines @@
  */
 abstract class BidirectionalIterator<E> implements Iterator<E> {
   /**
    * Move back to the previous element.
    *
    * Returns true and updates [current] if successful. Returns false
    * and sets [current] to null if there is no previous element.
    */
   bool movePrevious();
 }