main.dart

// Copyright 2014 The Flutter Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

class Foo {
  Foo({this.x, this.y});
  final int x;
  final int y;

  toString() => '($x, $y)';
}

List<Foo> generateWithElement() {
  return <Foo>[
    for (int i = 0; i < 1000; i++)
      Foo(x: i, y: i + 1)
  ];
}

List<Foo> generateWithFilled() {
  return List<Foo>.generate(1000, fill);
}


List<Foo> preallocate() {
  var result = List<Foo>(1000);
  for (int i = 0; i < 1000; i++)
    result[i] = Foo(x: i, y: i + 1);
  return result;
}

List<Foo> listAdd() {
  var result = <Foo>[];
  for (int i = 0; i < 1000; i++)
    result.add(Foo(x: i, y: i + 1));
  return result;
}

Foo fill(int value) {
  return Foo(x: value, y: value + 1);
}

void main() {
  var sw = Stopwatch();
  sw.start();
  List<Foo> result;
  for (var i = 0; i < 100; i++) {
    result = generateWithElement();
  }
  sw.stop();
  print(result.last);
  print('for element took ${sw.elapsedMicroseconds}');

  sw.reset();
  sw.start();
  for (var i = 0; i < 100; i++) {
    result = generateWithFilled();
  }
  sw.stop();
  print(result.last);
  print('List.generate took ${sw.elapsedMicroseconds}');

  sw.reset();
  sw.start();
  for (var i = 0; i < 100; i++) {
    result = preallocate();
  }
  sw.stop();
  print(result.last);
  print('preallocate took ${sw.elapsedMicroseconds}');

  sw.reset();
  sw.start();
  for (var i = 0; i < 100; i++) {
    result = listAdd();
  }
  sw.stop();
  print(result.last);
  print('List.add took ${sw.elapsedMicroseconds}');
}