d836ca5a68
Add a more efficient override of `Iterable.elementAt` in `CachingIterable`. Closes #152476
126 lines
3.7 KiB
Dart
126 lines
3.7 KiB
Dart
// Copyright 2014 The Flutter Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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import 'package:flutter/foundation.dart';
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import 'package:flutter_test/flutter_test.dart';
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int yieldCount = 0;
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Iterable<int> range(int start, int end) sync* {
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assert(yieldCount == 0);
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for (int index = start; index <= end; index += 1) {
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yieldCount += 1;
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yield index;
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}
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}
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void main() {
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setUp(() {
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yieldCount = 0;
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});
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test('The Caching Iterable: length caches', () {
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final Iterable<int> i = CachingIterable<int>(range(1, 5).iterator);
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expect(yieldCount, equals(0));
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expect(i.length, equals(5));
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expect(yieldCount, equals(5));
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expect(i.length, equals(5));
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expect(yieldCount, equals(5));
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expect(i.last, equals(5));
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expect(yieldCount, equals(5));
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expect(i, equals(<int>[1, 2, 3, 4, 5]));
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expect(yieldCount, equals(5));
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});
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test('The Caching Iterable: laziness', () {
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final Iterable<int> i = CachingIterable<int>(range(1, 5).iterator);
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expect(yieldCount, equals(0));
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expect(i.first, equals(1));
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expect(yieldCount, equals(1));
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expect(i.firstWhere((int i) => i == 3), equals(3));
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expect(yieldCount, equals(3));
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expect(i.last, equals(5));
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expect(yieldCount, equals(5));
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});
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test('The Caching Iterable: where and map', () {
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final Iterable<int> integers = CachingIterable<int>(range(1, 5).iterator);
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expect(yieldCount, equals(0));
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final Iterable<int> evens = integers.where((int i) => i.isEven);
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expect(yieldCount, equals(0));
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expect(evens.first, equals(2));
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expect(yieldCount, equals(2));
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expect(integers.first, equals(1));
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expect(yieldCount, equals(2));
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expect(evens.map<int>((int i) => i + 1), equals(<int>[3, 5]));
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expect(yieldCount, equals(5));
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expect(evens, equals(<int>[2, 4]));
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expect(yieldCount, equals(5));
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expect(integers, equals(<int>[1, 2, 3, 4, 5]));
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expect(yieldCount, equals(5));
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});
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test('The Caching Iterable: take and skip', () {
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final Iterable<int> integers = CachingIterable<int>(range(1, 5).iterator);
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expect(yieldCount, equals(0));
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final Iterable<int> secondTwo = integers.skip(1).take(2);
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expect(yieldCount, equals(0));
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expect(secondTwo, equals(<int>[2, 3]));
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expect(yieldCount, equals(3));
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final Iterable<int> result = integers.takeWhile((int i) => i < 4).skipWhile((int i) => i < 3);
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expect(result, equals(<int>[3]));
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expect(yieldCount, equals(4));
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expect(integers, equals(<int>[1, 2, 3, 4, 5]));
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expect(yieldCount, equals(5));
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});
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test('The Caching Iterable: expand', () {
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final Iterable<int> integers = CachingIterable<int>(range(1, 5).iterator);
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expect(yieldCount, equals(0));
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final Iterable<int> expanded1 = integers.expand<int>((int i) => <int>[i, i]);
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expect(yieldCount, equals(0));
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expect(expanded1, equals(<int>[1, 1, 2, 2, 3, 3, 4, 4, 5, 5]));
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expect(yieldCount, equals(5));
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final Iterable<int> expanded2 = integers.expand<int>((int i) => <int>[i, i]);
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expect(yieldCount, equals(5));
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expect(expanded2, equals(<int>[1, 1, 2, 2, 3, 3, 4, 4, 5, 5]));
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expect(yieldCount, equals(5));
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});
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test('The Caching Iterable: elementAt correctness', () {
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final Iterable<int> integers = CachingIterable<int>(range(1, 5).iterator);
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expect(yieldCount, equals(0));
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expect(() => integers.elementAt(-1), throwsRangeError);
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expect(integers.elementAt(1), equals(2));
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expect(integers.elementAt(0), equals(1));
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expect(integers.elementAt(2), equals(3));
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expect(integers.elementAt(4), equals(5));
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expect(integers.elementAt(3), equals(4));
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expect(() => integers.elementAt(5), throwsRangeError);
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});
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}
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