Line data    Source code

       1             : /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
       2             : /* vim: set ts=8 sts=2 et sw=2 tw=80: */
       3             : /* This Source Code Form is subject to the terms of the Mozilla Public
       4             :  * License, v. 2.0. If a copy of the MPL was not distributed with this
       5             :  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
       6             : 
       7             : /* An opaque integral type supporting only comparison operators. */
       8             : 
       9             : #ifndef mozilla_Opaque_h
      10             : #define mozilla_Opaque_h
      11             : 
      12             : #include "mozilla/TypeTraits.h"
      13             : 
      14             : namespace mozilla {
      15             : 
      16             : /**
      17             :  * Opaque<T> is a replacement for integral T in cases where only comparisons
      18             :  * must be supported, and it's desirable to prevent accidental dependency on
      19             :  * exact values.
      20             :  */
      21             : template<typename T>
      22             : class Opaque final
      23             : {
      24             :   static_assert(mozilla::IsIntegral<T>::value,
      25             :                 "mozilla::Opaque only supports integral types");
      26             : 
      27             :   T mValue;
      28             : 
      29             : public:
      30             :   Opaque() {}
      31    16609743 :   explicit Opaque(T aValue) : mValue(aValue) {}
      32             : 
      33    12069285 :   bool operator==(const Opaque& aOther) const {
      34    12069285 :     return mValue == aOther.mValue;
      35             :   }
      36             : 
      37           0 :   bool operator!=(const Opaque& aOther) const {
      38           0 :     return !(*this == aOther);
      39             :   }
      40             : };
      41             : 
      42             : } // namespace mozilla
      43             : 
      44             : #endif /* mozilla_Opaque_h */