| // Copyright (c) 2019, 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. |
| |
| /// @assertion Dynamic Semantics |
| /// The new dynamic semantics are a superset of the original behavior. To avoid |
| /// redundancy and handle nested uses, the semantics are expressed in terms of a |
| /// separate procedure below: |
| /// . . . |
| /// Sets |
| /// |
| /// 1. Create a fresh instance [collection] of a class that implements [Set<E>]. |
| /// |
| /// 2. For each [element] in the set literal: |
| /// i. Evaluate [element] using the procedure below. |
| /// |
| /// 3. The result of the literal expression is [collection]. |
| /// . . . |
| /// To evaluate a collection [element]: |
| /// This procedure handles elements in both list and map literals because the |
| /// only difference is how a base expression element or entry element is handled. |
| /// The control flow parts are the same so are unified here. |
| /// |
| /// 2. Else, if [element] is a synchronous [for-in] element: |
| /// |
| /// i. Evaluate the iterator expression to a value [sequence]. |
| /// ii. Evaluate [sequence.iterator] to a value [iterator]. |
| /// iii. Loop: |
| /// a. If the boolean conversion of [iterator.moveNext()] does not |
| /// return [true], exit the loop. |
| /// b. If the [for-in] element declares a variable, create a fresh |
| /// [variable] for it. Otherwise, use the existing [variable] it |
| /// refers to. |
| /// c. Evaluate [iterator.current] and bind it to [variable]. |
| /// d. Evaluate the body element using this procedure in the scope of |
| /// [variable]. |
| /// iv. If the [for-in] element declares a variable, discard it. |
| /// . . . |
| /// @description Checks that if [element] of set literal is a synchronous |
| /// [for-in] element, this element is evaluated using the specified procedure. |
| /// @author ngl@unipro.ru |
| |
| import "../../Utils/expect.dart"; |
| |
| main() { |
| var l1 = [1, 2]; |
| var l2 = [3, 4, 5]; |
| |
| var set1exp = new Set<int>(); |
| var n0 = l1.iterator; |
| while (n0.moveNext()) { |
| var id = n0.current; |
| set1exp.add(id); |
| } |
| n0 = l2.iterator; |
| while (n0.moveNext()) { |
| var id = n0.current; |
| if (id.isOdd) { |
| set1exp.add(id + 1); |
| } |
| } |
| Expect.isTrue(set1exp is Set<int>); |
| Expect.runtimeIsType<Set<int>>(set1exp); |
| |
| var set1 = <int>{for (var v in l1) v, for (var v in l2) if (v.isOdd) (v + 1)}; |
| // set1exp {1, 2, 4, 6} |
| Expect.setEquals(set1exp, set1); |
| Expect.isTrue(set1 is Set<int>); |
| Expect.runtimeIsType<Set<int>>(set1); |
| } |