Robert Nystrom | 284f662 | 2019-12-02 23:19:10 +0000 | [diff] [blame] | 1 | // Copyright (c) 2013, the Dart project authors. Please see the AUTHORS file |
| 2 | // for details. All rights reserved. Use of this source code is governed by a |
| 3 | // BSD-style license that can be found in the LICENSE file. |
| 4 | |
| 5 | import "package:expect/expect.dart"; |
| 6 | |
| 7 | main() { |
| 8 | void test(expectedList, generatedIterable) { |
| 9 | Expect.equals(expectedList.length, generatedIterable.length); |
| 10 | Expect.listEquals(expectedList, generatedIterable.toList()); |
| 11 | } |
| 12 | |
| 13 | test([], new Iterable.generate(0)); |
| 14 | test([0], new Iterable.generate(1)); |
| 15 | test([0, 1, 2, 3, 4], new Iterable.generate(5)); |
| 16 | test(["0", "1", "2", "3", "4"], new Iterable.generate(5, (x) => "$x")); |
| 17 | test([2, 3, 4, 5, 6], new Iterable.generate(7).skip(2)); |
| 18 | test([0, 1, 2, 3, 4], new Iterable.generate(7).take(5)); |
| 19 | test([], new Iterable.generate(5).skip(6)); |
| 20 | test([], new Iterable.generate(5).take(0)); |
| 21 | test([], new Iterable.generate(5).take(3).skip(3)); |
| 22 | test([], new Iterable.generate(5).skip(6).take(0)); |
| 23 | |
| 24 | // Test types. |
| 25 | |
| 26 | Iterable<int> it = new Iterable<int>.generate(5); |
| 27 | Expect.isTrue(it is Iterable<int>); |
| 28 | Expect.isTrue(it.iterator is Iterator<int>); |
| 29 | Expect.isTrue(it is! Iterable<String>); |
| 30 | Expect.isTrue(it.iterator is! Iterator<String>); |
| 31 | test([0, 1, 2, 3, 4], it); |
| 32 | |
| 33 | Iterable<String> st = new Iterable<String>.generate(5, (x) => "$x"); |
| 34 | Expect.isTrue(st is Iterable<String>); |
| 35 | Expect.isTrue(st.iterator is Iterator<String>); |
| 36 | Expect.isFalse(st is Iterable<int>); |
| 37 | Expect.isFalse(st.iterator is Iterator<int>); |
| 38 | test(["0", "1", "2", "3", "4"], st); |
| 39 | |
| 40 | Expect.throws(() => new Iterable<String>.generate(5)); |
| 41 | |
| 42 | // Omitted generator function means `(int x) => x`, and the type parameters |
| 43 | // must then be compatible with `int`. |
| 44 | // Check that we catch invalid type parameters. |
| 45 | |
| 46 | // Valid types: |
| 47 | Iterable<int> iter1 = new Iterable<int>.generate(5); |
| 48 | Expect.equals(2, iter1.elementAt(2)); |
| 49 | Iterable<num> iter2 = new Iterable<num>.generate(5); |
| 50 | Expect.equals(2, iter2.elementAt(2)); |
| 51 | Iterable<Object> iter3 = new Iterable<Object>.generate(5); |
| 52 | Expect.equals(2, iter3.elementAt(2)); |
| 53 | Iterable<dynamic> iter4 = new Iterable<dynamic>.generate(5); |
| 54 | Expect.equals(2, iter4.elementAt(2)); |
| 55 | |
| 56 | // Invalid types: |
| 57 | Expect.throws(() => new Iterable<String>.generate(5)); |
| 58 | Expect.throws(() => new Iterable<Null>.generate(5).elementAt(2)); //# 01: ok |
| 59 | Expect.throws(() => new Iterable<bool>.generate(5)); |
| 60 | |
| 61 | // Regression: https://github.com/dart-lang/sdk/issues/26358 |
| 62 | var count = 0; |
| 63 | var iter = new Iterable.generate(5, (v) { |
| 64 | count++; |
| 65 | return v; |
| 66 | }); |
| 67 | Expect.equals(0, count); |
| 68 | Expect.equals(2, iter.elementAt(2)); // Doesn't compute the earlier values. |
| 69 | Expect.equals(1, count); |
| 70 | Expect.equals(2, iter.skip(2).first); // Doesn't compute the skipped values. |
| 71 | Expect.equals(2, count); |
| 72 | } |