Language/Expressions/Unary_Expressions/syntax_t01.dart

// Copyright (c) 2011, 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 Unary expressions invoke unary operators on objects.
/// unaryExpression:
///   prefixOperator unaryExpression |
///   awaitExpression |
///   postfixExpression |
///   (minusOperator | tildeOperator) super |
///   incrementOperator assignableExpression
/// ;
/// prefixOperator:
///   minusOperator |
///   negationOperator |
///   tildeOperator
/// ;
/// minusOperator:
///   ‘-’ |
/// ;
/// negationOperator:
///   ‘!’ |
/// ;
/// tildeOperator:
///   ‘˜’
/// ;
/// A unary expression is either a postfix expression, an await expression or
/// an invocation of a prefix operator on an expression or an invocation of a
/// unary operator on either super or an expression e.
/// @description Checks that expressions composed from prefix/unary operators and
/// super that fit into this production don't cause compile-time errors.
/// @author msyabro


class S {
  var x = 1;
  operator -() { return this; }
  operator ~() { return this; }
}

class A extends S {
  test() {
    -super;
    ~super;
    - -super; // should be interpreted as -(-super);
    ~~super;
    try {
      !-super;
    } catch (ok) {}
    ~-super;
    -~super;
    try {
      !~super;
    } catch (ok) {}
  }
}

main() {
  A a = new A();
  a.test();
}