include/QtCore/qflags.h

0001 // Copyright (C) 2016 The Qt Company Ltd.
0002 // SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
0003
0004 #ifndef QFLAGS_H
0005 #define QFLAGS_H
0006
0007 #include <QtCore/qcompare_impl.h>
0008 #include <QtCore/qtypeinfo.h>
0009
0010 #include <initializer_list>
0011
0012 QT_BEGIN_NAMESPACE
0013
0014 class QDataStream;
0015
0016 class QFlag
0017 {
0018     int i;
0019 public:
0020     constexpr inline Q_IMPLICIT QFlag(int value) noexcept : i(value) {}
0021     constexpr inline Q_IMPLICIT operator int() const noexcept { return i; }
0022
0023 #if !defined(Q_CC_MSVC)
0024     // Microsoft Visual Studio has buggy behavior when it comes to
0025     // unsigned enums: even if the enum is unsigned, the enum tags are
0026     // always signed
0027 #  if !defined(__LP64__) && !defined(Q_QDOC)
0028     constexpr inline Q_IMPLICIT QFlag(long value) noexcept : i(int(value)) {}
0029     constexpr inline Q_IMPLICIT QFlag(ulong value) noexcept : i(int(long(value))) {}
0030 #  endif
0031     constexpr inline Q_IMPLICIT QFlag(uint value) noexcept : i(int(value)) {}
0032     constexpr inline Q_IMPLICIT QFlag(short value) noexcept : i(int(value)) {}
0033     constexpr inline Q_IMPLICIT QFlag(ushort value) noexcept : i(int(uint(value))) {}
0034     constexpr inline Q_IMPLICIT operator uint() const noexcept { return uint(i); }
0035 #endif
0036 };
0037 Q_DECLARE_TYPEINFO(QFlag, Q_PRIMITIVE_TYPE);
0038
0039 class QIncompatibleFlag
0040 {
0041     int i;
0042 public:
0043     constexpr inline explicit QIncompatibleFlag(int i) noexcept;
0044     constexpr inline Q_IMPLICIT operator int() const noexcept { return i; }
0045 };
0046 Q_DECLARE_TYPEINFO(QIncompatibleFlag, Q_PRIMITIVE_TYPE);
0047
0048 constexpr inline QIncompatibleFlag::QIncompatibleFlag(int value) noexcept : i(value) {}
0049
0050
0051 template<typename Enum>
0052 class QFlags
0053 {
0054     static_assert((sizeof(Enum) <= sizeof(int)),
0055                   "QFlags uses an int as storage, so an enum with underlying "
0056                   "long long will overflow.");
0057     static_assert((std::is_enum<Enum>::value), "QFlags is only usable on enumeration types.");
0058
0059 public:
0060 #if defined(Q_CC_MSVC) || defined(Q_QDOC)
0061     // see above for MSVC
0062     // the definition below is too complex for qdoc
0063     typedef int Int;
0064 #else
0065     typedef typename std::conditional<
0066             std::is_unsigned<typename std::underlying_type<Enum>::type>::value,
0067             unsigned int,
0068             signed int
0069         >::type Int;
0070 #endif
0071     typedef Enum enum_type;
0072     // compiler-generated copy/move ctor/assignment operators are fine!
0073     constexpr inline QFlags() noexcept : i(0) {}
0074     constexpr inline Q_IMPLICIT QFlags(Enum flags) noexcept : i(Int(flags)) {}
0075     constexpr inline Q_IMPLICIT QFlags(QFlag flag) noexcept : i(flag) {}
0076
0077     constexpr inline QFlags(std::initializer_list<Enum> flags) noexcept
0078         : i(initializer_list_helper(flags.begin(), flags.end())) {}
0079
0080     constexpr static inline QFlags fromInt(Int i) noexcept { return QFlags(QFlag(i)); }
0081     constexpr inline Int toInt() const noexcept { return i; }
0082
0083 #ifndef QT_TYPESAFE_FLAGS
0084     constexpr inline QFlags &operator&=(int mask) noexcept { i &= mask; return *this; }
0085     constexpr inline QFlags &operator&=(uint mask) noexcept { i &= mask; return *this; }
0086 #endif
0087     constexpr inline QFlags &operator&=(QFlags mask) noexcept { i &= mask.i; return *this; }
0088     constexpr inline QFlags &operator&=(Enum mask) noexcept { i &= Int(mask); return *this; }
0089     constexpr inline QFlags &operator|=(QFlags other) noexcept { i |= other.i; return *this; }
0090     constexpr inline QFlags &operator|=(Enum other) noexcept { i |= Int(other); return *this; }
0091     constexpr inline QFlags &operator^=(QFlags other) noexcept { i ^= other.i; return *this; }
0092     constexpr inline QFlags &operator^=(Enum other) noexcept { i ^= Int(other); return *this; }
0093
0094 #ifdef QT_TYPESAFE_FLAGS
0095     constexpr inline explicit operator Int() const noexcept { return i; }
0096     constexpr inline explicit operator bool() const noexcept { return i; }
0097     // For some reason, moc goes through QFlag in order to read/write
0098     // properties of type QFlags; so a conversion to QFlag is also
0099     // needed here. (It otherwise goes through a QFlags->int->QFlag
0100     // conversion sequence.)
0101     constexpr inline explicit operator QFlag() const noexcept { return QFlag(i); }
0102 #else
0103     constexpr inline Q_IMPLICIT operator Int() const noexcept { return i; }
0104     constexpr inline bool operator!() const noexcept { return !i; }
0105 #endif
0106
0107     constexpr inline QFlags operator|(QFlags other) const noexcept { return QFlags(QFlag(i | other.i)); }
0108     constexpr inline QFlags operator|(Enum other) const noexcept { return QFlags(QFlag(i | Int(other))); }
0109     constexpr inline QFlags operator^(QFlags other) const noexcept { return QFlags(QFlag(i ^ other.i)); }
0110     constexpr inline QFlags operator^(Enum other) const noexcept { return QFlags(QFlag(i ^ Int(other))); }
0111 #ifndef QT_TYPESAFE_FLAGS
0112     constexpr inline QFlags operator&(int mask) const noexcept { return QFlags(QFlag(i & mask)); }
0113     constexpr inline QFlags operator&(uint mask) const noexcept { return QFlags(QFlag(i & mask)); }
0114 #endif
0115     constexpr inline QFlags operator&(QFlags other) const noexcept { return QFlags(QFlag(i & other.i)); }
0116     constexpr inline QFlags operator&(Enum other) const noexcept { return QFlags(QFlag(i & Int(other))); }
0117     constexpr inline QFlags operator~() const noexcept { return QFlags(QFlag(~i)); }
0118
0119     constexpr inline void operator+(QFlags other) const noexcept = delete;
0120     constexpr inline void operator+(Enum other) const noexcept = delete;
0121     constexpr inline void operator+(int other) const noexcept = delete;
0122     constexpr inline void operator-(QFlags other) const noexcept = delete;
0123     constexpr inline void operator-(Enum other) const noexcept = delete;
0124     constexpr inline void operator-(int other) const noexcept = delete;
0125
0126     constexpr inline bool testFlag(Enum flag) const noexcept { return testFlags(flag); }
0127     constexpr inline bool testFlags(QFlags flags) const noexcept { return flags.i ? ((i & flags.i) == flags.i) : i == Int(0); }
0128     constexpr inline bool testAnyFlag(Enum flag) const noexcept { return testAnyFlags(flag); }
0129     constexpr inline bool testAnyFlags(QFlags flags) const noexcept { return (i & flags.i) != Int(0); }
0130     constexpr inline QFlags &setFlag(Enum flag, bool on = true) noexcept
0131     {
0132         return on ? (*this |= flag) : (*this &= ~QFlags(flag));
0133     }
0134
0135     friend constexpr inline bool operator==(QFlags lhs, QFlags rhs) noexcept
0136     { return lhs.i == rhs.i; }
0137     friend constexpr inline bool operator!=(QFlags lhs, QFlags rhs) noexcept
0138     { return lhs.i != rhs.i; }
0139     friend constexpr inline bool operator==(QFlags lhs, Enum rhs) noexcept
0140     { return lhs == QFlags(rhs); }
0141     friend constexpr inline bool operator!=(QFlags lhs, Enum rhs) noexcept
0142     { return lhs != QFlags(rhs); }
0143     friend constexpr inline bool operator==(Enum lhs, QFlags rhs) noexcept
0144     { return QFlags(lhs) == rhs; }
0145     friend constexpr inline bool operator!=(Enum lhs, QFlags rhs) noexcept
0146     { return QFlags(lhs) != rhs; }
0147
0148 #ifdef QT_TYPESAFE_FLAGS
0149     // Provide means of comparing flags against a literal 0; opt-in
0150     // because otherwise they're ambiguous against operator==(int,int)
0151     // after a QFlags->int conversion.
0152     friend constexpr inline bool operator==(QFlags flags, QtPrivate::CompareAgainstLiteralZero) noexcept
0153     { return flags.i == Int(0); }
0154     friend constexpr inline bool operator!=(QFlags flags, QtPrivate::CompareAgainstLiteralZero) noexcept
0155     { return flags.i != Int(0); }
0156     friend constexpr inline bool operator==(QtPrivate::CompareAgainstLiteralZero, QFlags flags) noexcept
0157     { return Int(0) == flags.i; }
0158     friend constexpr inline bool operator!=(QtPrivate::CompareAgainstLiteralZero, QFlags flags) noexcept
0159     { return Int(0) != flags.i; }
0160 #endif
0161
0162 private:
0163     constexpr static inline Int initializer_list_helper(typename std::initializer_list<Enum>::const_iterator it,
0164                                                                typename std::initializer_list<Enum>::const_iterator end)
0165     noexcept
0166     {
0167         return (it == end ? Int(0) : (Int(*it) | initializer_list_helper(it + 1, end)));
0168     }
0169
0170     Int i;
0171 };
0172
0173 #ifndef Q_MOC_RUN
0174 #define Q_DECLARE_FLAGS(Flags, Enum)\
0175 typedef QFlags<Enum> Flags;
0176 #endif
0177
0178 #ifdef QT_TYPESAFE_FLAGS
0179
0180 // These are opt-in, for backwards compatibility
0181 #define QT_DECLARE_TYPESAFE_OPERATORS_FOR_FLAGS_ENUM(Flags) \
0182 [[maybe_unused]] \
0183 constexpr inline Flags operator~(Flags::enum_type e) noexcept \
0184 { return ~Flags(e); } \
0185 [[maybe_unused]] \
0186 constexpr inline void operator|(Flags::enum_type f1, int f2) noexcept = delete;
0187 #else
0188 #define QT_DECLARE_TYPESAFE_OPERATORS_FOR_FLAGS_ENUM(Flags) \
0189 [[maybe_unused]] \
0190 constexpr inline QIncompatibleFlag operator|(Flags::enum_type f1, int f2) noexcept \
0191 { return QIncompatibleFlag(int(f1) | f2); }
0192 #endif
0193
0194 #define Q_DECLARE_OPERATORS_FOR_FLAGS(Flags) \
0195 [[maybe_unused]] \
0196 constexpr inline QFlags<Flags::enum_type> operator|(Flags::enum_type f1, Flags::enum_type f2) noexcept \
0197 { return QFlags<Flags::enum_type>(f1) | f2; } \
0198 [[maybe_unused]] \
0199 constexpr inline QFlags<Flags::enum_type> operator|(Flags::enum_type f1, QFlags<Flags::enum_type> f2) noexcept \
0200 { return f2 | f1; } \
0201 [[maybe_unused]] \
0202 constexpr inline QFlags<Flags::enum_type> operator&(Flags::enum_type f1, Flags::enum_type f2) noexcept \
0203 { return QFlags<Flags::enum_type>(f1) & f2; } \
0204 [[maybe_unused]] \
0205 constexpr inline QFlags<Flags::enum_type> operator&(Flags::enum_type f1, QFlags<Flags::enum_type> f2) noexcept \
0206 { return f2 & f1; } \
0207 [[maybe_unused]] \
0208 constexpr inline QFlags<Flags::enum_type> operator^(Flags::enum_type f1, Flags::enum_type f2) noexcept \
0209 { return QFlags<Flags::enum_type>(f1) ^ f2; } \
0210 [[maybe_unused]] \
0211 constexpr inline QFlags<Flags::enum_type> operator^(Flags::enum_type f1, QFlags<Flags::enum_type> f2) noexcept \
0212 { return f2 ^ f1; } \
0213 constexpr inline void operator+(Flags::enum_type f1, Flags::enum_type f2) noexcept = delete; \
0214 constexpr inline void operator+(Flags::enum_type f1, QFlags<Flags::enum_type> f2) noexcept = delete; \
0215 constexpr inline void operator+(int f1, QFlags<Flags::enum_type> f2) noexcept = delete; \
0216 constexpr inline void operator-(Flags::enum_type f1, Flags::enum_type f2) noexcept = delete; \
0217 constexpr inline void operator-(Flags::enum_type f1, QFlags<Flags::enum_type> f2) noexcept = delete; \
0218 constexpr inline void operator-(int f1, QFlags<Flags::enum_type> f2) noexcept = delete; \
0219 constexpr inline void operator+(int f1, Flags::enum_type f2) noexcept = delete; \
0220 constexpr inline void operator+(Flags::enum_type f1, int f2) noexcept = delete; \
0221 constexpr inline void operator-(int f1, Flags::enum_type f2) noexcept = delete; \
0222 constexpr inline void operator-(Flags::enum_type f1, int f2) noexcept = delete; \
0223 QT_DECLARE_TYPESAFE_OPERATORS_FOR_FLAGS_ENUM(Flags)
0224
0225 // restore bit-wise enum-enum operators deprecated in C++20,
0226 // but used in a few places in the API
0227 #if __cplusplus > 201702L // assume compilers don't warn if in C++17 mode
0228   // in C++20 mode, provide user-defined operators to override the deprecated operations:
0229 # define Q_DECLARE_MIXED_ENUM_OPERATOR(op, Ret, LHS, RHS) \
0230     [[maybe_unused]] \
0231     constexpr inline Ret operator op (LHS lhs, RHS rhs) noexcept \
0232     { return static_cast<Ret>(qToUnderlying(lhs) op qToUnderlying(rhs)); } \
0233     /* end */
0234 #else
0235   // in C++17 mode, statically-assert that this compiler's result of the
0236   // operation is the same that the C++20 version would produce:
0237 # define Q_DECLARE_MIXED_ENUM_OPERATOR(op, Ret, LHS, RHS) \
0238     static_assert(std::is_same_v<decltype(std::declval<LHS>() op std::declval<RHS>()), Ret>);
0239 #endif
0240
0241 #define Q_DECLARE_MIXED_ENUM_OPERATORS(Ret, Flags, Enum) \
0242     Q_DECLARE_MIXED_ENUM_OPERATOR(|, Ret, Flags, Enum) \
0243     Q_DECLARE_MIXED_ENUM_OPERATOR(&, Ret, Flags, Enum) \
0244     Q_DECLARE_MIXED_ENUM_OPERATOR(^, Ret, Flags, Enum) \
0245     /* end */
0246
0247 #define Q_DECLARE_MIXED_ENUM_OPERATORS_SYMMETRIC(Ret, Flags, Enum) \
0248     Q_DECLARE_MIXED_ENUM_OPERATORS(Ret, Flags, Enum) \
0249     Q_DECLARE_MIXED_ENUM_OPERATORS(Ret, Enum, Flags) \
0250     /* end */
0251
0252
0253 QT_END_NAMESPACE
0254
0255 #endif // QFLAGS_H