| // 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: |
| /// . . . |
| /// Maps |
| /// A map literal of the form [<K, V>{entry_1 ... entry_n}] is evaluated as |
| /// follows: |
| /// 1. Allocate a fresh instance [map] of a class that implements |
| /// [LinkedHashMap<K, V>]. |
| /// |
| /// 2. For each [element] in the map literal: |
| /// i. Evaluate [element] using the procedure below. |
| /// |
| /// 3. The result of the map literal expression is [map]. |
| /// . . . |
| /// 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 map 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 m2 = [MapEntry(1, 'a'), MapEntry(2, 'b'), MapEntry(3, 'c'), |
| MapEntry(4, 'd'), MapEntry(5, 'e')]; |
| |
| var map1exp = <int, String>{}; |
| var n0 = m2.iterator; |
| while (n0.moveNext()) { |
| var id = n0.current; |
| map1exp[id.key] = id.value; |
| } |
| Expect.isTrue(map1exp is Map<int, String>); |
| Expect.runtimeIsType<Map<int, String>>(map1exp); |
| |
| var map1 = <int, String>{for (var v in m2) v.key: v.value}; |
| // map1exp {1: a, 2: b, 3: c, 4: d, 5: e} |
| Expect.isTrue(map1 is Map<int, String>); |
| Expect.runtimeIsType<Map<int, String>>(map1); |
| Expect.mapEquals(map1exp, map1); |
| } |