mirror of
https://gitlab.winehq.org/wine/wine-gecko.git
synced 2024-09-13 09:24:08 -07:00
111 lines
3.7 KiB
C++
111 lines
3.7 KiB
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/. */
|
|
|
|
/* Internal stuff needed by TypedEnum.h and TypedEnumBits.h. */
|
|
|
|
// NOTE: When we can assume C++11 enum class support and TypedEnum.h goes away,
|
|
// we should then consider folding TypedEnumInternal.h into TypedEnumBits.h.
|
|
|
|
#ifndef mozilla_TypedEnumInternal_h
|
|
#define mozilla_TypedEnumInternal_h
|
|
|
|
#include "mozilla/Attributes.h"
|
|
|
|
#if defined(__cplusplus)
|
|
|
|
#if defined(__clang__)
|
|
/*
|
|
* Per Clang documentation, "Note that marketing version numbers should not
|
|
* be used to check for language features, as different vendors use different
|
|
* numbering schemes. Instead, use the feature checking macros."
|
|
*/
|
|
# ifndef __has_extension
|
|
# define __has_extension __has_feature /* compatibility, for older versions of clang */
|
|
# endif
|
|
# if __has_extension(cxx_strong_enums)
|
|
# define MOZ_HAVE_CXX11_ENUM_TYPE
|
|
# define MOZ_HAVE_CXX11_STRONG_ENUMS
|
|
# endif
|
|
#elif defined(__GNUC__)
|
|
# if defined(__GXX_EXPERIMENTAL_CXX0X__) || __cplusplus >= 201103L
|
|
# if MOZ_GCC_VERSION_AT_LEAST(4, 6, 3)
|
|
# define MOZ_HAVE_CXX11_ENUM_TYPE
|
|
# define MOZ_HAVE_CXX11_STRONG_ENUMS
|
|
# endif
|
|
# endif
|
|
#elif defined(_MSC_VER)
|
|
# if _MSC_VER >= 1400
|
|
# define MOZ_HAVE_CXX11_ENUM_TYPE
|
|
# endif
|
|
# if _MSC_VER >= 1700
|
|
# define MOZ_HAVE_CXX11_STRONG_ENUMS
|
|
# endif
|
|
#endif
|
|
|
|
namespace mozilla {
|
|
|
|
/*
|
|
* The problem that CastableTypedEnumResult aims to solve is that
|
|
* typed enums are not convertible to bool, and there is no way to make them
|
|
* be, yet user code wants to be able to write
|
|
*
|
|
* if (myFlags & Flags::SOME_PARTICULAR_FLAG) (1)
|
|
*
|
|
* There are different approaches to solving this. Most of them require
|
|
* adapting user code. For example, we could implement operator! and have
|
|
* the user write
|
|
*
|
|
* if (!!(myFlags & Flags::SOME_PARTICULAR_FLAG)) (2)
|
|
*
|
|
* Or we could supply a IsNonZero() or Any() function returning whether
|
|
* an enum value is nonzero, and have the user write
|
|
*
|
|
* if (Any(Flags & Flags::SOME_PARTICULAR_FLAG)) (3)
|
|
*
|
|
* But instead, we choose to preserve the original user syntax (1) as it
|
|
* is inherently more readable, and to ease porting existing code to typed
|
|
* enums. We achieve this by having operator& and other binary bitwise
|
|
* operators have as return type a class, CastableTypedEnumResult,
|
|
* that wraps a typed enum but adds bool convertibility.
|
|
*/
|
|
template<typename E>
|
|
class CastableTypedEnumResult
|
|
{
|
|
private:
|
|
const E mValue;
|
|
|
|
public:
|
|
explicit MOZ_CONSTEXPR CastableTypedEnumResult(E aValue)
|
|
: mValue(aValue)
|
|
{}
|
|
|
|
MOZ_CONSTEXPR operator E() const { return mValue; }
|
|
|
|
template<typename DestinationType>
|
|
MOZ_EXPLICIT_CONVERSION MOZ_CONSTEXPR
|
|
operator DestinationType() const { return DestinationType(mValue); }
|
|
|
|
MOZ_CONSTEXPR bool operator !() const { return !bool(mValue); }
|
|
|
|
#ifndef MOZ_HAVE_CXX11_STRONG_ENUMS
|
|
// This get() method is used to implement a constructor in the
|
|
// non-c++11 fallback path for MOZ_BEGIN_ENUM_CLASS, taking a
|
|
// CastableTypedEnumResult. If we try to implement it using the
|
|
// above conversion operator E(), then at least clang 3.3
|
|
// (when forced to take the non-c++11 fallback path) compiles
|
|
// this constructor to an infinite recursion. So we introduce this
|
|
// get() method, that does exactly the same as the conversion operator,
|
|
// to work around this.
|
|
MOZ_CONSTEXPR E get() const { return mValue; }
|
|
#endif
|
|
};
|
|
|
|
} // namespace mozilla
|
|
|
|
#endif // __cplusplus
|
|
|
|
#endif // mozilla_TypedEnumInternal_h
|