gecko-dev/mfbt/Opaque.h

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C++

/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
/* An opaque integral type supporting only comparison operators. */
#ifndef mozilla_Opaque_h
#define mozilla_Opaque_h
#include "mozilla/TypeTraits.h"
namespace mozilla {
/**
* Opaque<T> is a replacement for integral T in cases where only comparisons
* must be supported, and it's desirable to prevent accidental dependency on
* exact values.
*/
template<typename T>
class Opaque final
{
static_assert(mozilla::IsIntegral<T>::value,
"mozilla::Opaque only supports integral types");
T mValue;
public:
Opaque() {}
explicit Opaque(T aValue) : mValue(aValue) {}
bool operator==(const Opaque& aOther) const {
return mValue == aOther.mValue;
}
bool operator!=(const Opaque& aOther) const {
return !(*this == aOther);
}
};
} // namespace mozilla
#endif /* mozilla_Opaque_h */