dart / co19 / 74ba459aecc908d5db91531f020a3f74e9aa1b4d / . / LanguageFeatures / Set-literals / type_inference_A26_t03.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. | |

/// @assertion Finally, we define inference on a setOrMapLiteral collection as | |

/// follows: | |

/// ... | |

/// Otherwise, collection is still ambiguous, the downwards context for the | |

/// elements of collection is ?, and the disambiguation is done using the | |

/// immediate elements of collection as follows: | |

/// | |

/// If all elements can be a set, and at least one element must be a set, then | |

/// collection is a set literal with static type Set<T> where T is the least | |

/// upper bound of the set element types of the elements. | |

/// | |

/// @description Checks that if all elements can be a set, and at least one | |

/// element must be a set, then collection is a set literal with static type | |

/// Set<T> where T is the least upper bound of the set element types of the | |

/// elements | |

/// @author sgrekhov@unipro.ru | |

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

main() { | |

var n = null; | |

var s1 = {...?n, 1}; | |

Expect.isTrue(s1 is Set<Object?>); | |

Expect.isFalse(s1 is Set<int>); | |

Expect.isFalse(s1 is Set<Null>); | |

Expect.runtimeIsType<Set<Object?>>(s1); | |

Expect.runtimeIsNotType<Set<int>>(s1); | |

Expect.runtimeIsNotType<Set<Null>>(s1); | |

var s2 = {1, ...?n}; | |

Expect.isTrue(s2 is Set<Object?>); | |

Expect.isFalse(s2 is Set<int>); | |

Expect.isFalse(s2 is Set<Null>); | |

Expect.runtimeIsType<Set<Object?>>(s2); | |

Expect.runtimeIsNotType<Set<int>>(s2); | |

Expect.runtimeIsNotType<Set<Null>>(s2); | |

} |