LanguageFeatures/Spread-collections/Syntax_A02_t10.dart

// 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.

// @dart = 2.9

/// @assertion The grammar changes for map and set are a little more complex
/// because of the potential ambiguity of collections containing only spreads.
/// The changed and new rules are:
///
///    setOrMapLiteral:
///    mapLiteral |
///    setLiteral |
///    mapOrSetLiteral
///    ;
///
///    mapLiteral:
///    const? typeArguments? '{' mapLiteralEntryList? '}'
///    ;
///
///    mapLiteralEntryList:
///    mapLiteralEntry ( ',' mapLiteralEntry )* ','?
///    ;
///
///    mapLiteralEntry:
///    expression ':' expression |
///    spread
///    ;
///
///    setLiteral:
///    'const'? typeArguments? '{' spreadableList '}' ;
///
///    mapOrSetLiteral:
///    'const'?  '{' spread (',' spread)* '}' ;
///
/// @description Checks that spreadable element can be null-aware in spreadable
/// set
/// @author iarkh@unipro.ru


import "../../Utils/expect.dart";

main() {
  List list1 = null;
  List set = null;

  Set a;

  Expect.setEquals([].toSet(), {...?list1});
  Expect.throws(() => a = {...list1});

  Expect.setEquals({12}, {12, ...?list1});
  Expect.throws(() => a = {12, ...list1});

  Expect.setEquals({...?list1, 12}, {12});
  Expect.throws(() => a = {...list1, 12});

  Expect.setEquals([].toSet(), {...?set});
  Expect.throws(() => a = {...set});

  Expect.setEquals({12}, {12, ...?set});
  Expect.throws(() => a = {12, ...set});

  Expect.setEquals({12}, {...?set, 12});
  Expect.throws(() => a = {...set, 12});
}