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Diffstat (limited to 'src/qml/qml/ftw/qbipointer_p.h')
| -rw-r--r-- | src/qml/qml/ftw/qbipointer_p.h | 203 |
1 files changed, 203 insertions, 0 deletions
diff --git a/src/qml/qml/ftw/qbipointer_p.h b/src/qml/qml/ftw/qbipointer_p.h new file mode 100644 index 0000000000..1597b9e4fc --- /dev/null +++ b/src/qml/qml/ftw/qbipointer_p.h @@ -0,0 +1,203 @@ +// Copyright (C) 2021 The Qt Company Ltd. +// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only + +#ifndef QBIPOINTER_P_H +#define QBIPOINTER_P_H + +// +// W A R N I N G +// ------------- +// +// This file is not part of the Qt API. It exists purely as an +// implementation detail. This header file may change from version to +// version without notice, or even be removed. +// +// We mean it. +// + +#include <QtCore/private/qglobal_p.h> + +#include <QtCore/qhashfunctions.h> + +QT_BEGIN_NAMESPACE + +namespace QtPrivate { +template <typename T> struct QFlagPointerAlignment +{ + enum : size_t { Value = Q_ALIGNOF(T) }; +}; +template <> struct QFlagPointerAlignment<void> +{ + enum : size_t { Value = ~size_t(0) }; +}; +} + +/*! + \internal + \class template<typename T1, typename T2> QBiPointer<T1, T2> + + \short QBiPointer can be thought of as a space-optimized std::variant<T1*, T2*> + with a nicer API to check the active pointer. Its other main feature is that + it only requires sizeof(void *) space. + + \note It can also store one additional flag for a user defined purpose. + */ +template<typename T, typename T2> +class QBiPointer { +public: + Q_NODISCARD_CTOR constexpr QBiPointer() noexcept = default; + ~QBiPointer() noexcept = default; + Q_NODISCARD_CTOR QBiPointer(const QBiPointer &o) noexcept = default; + Q_NODISCARD_CTOR QBiPointer(QBiPointer &&o) noexcept = default; + QBiPointer<T, T2> &operator=(const QBiPointer<T, T2> &o) noexcept = default; + QBiPointer<T, T2> &operator=(QBiPointer<T, T2> &&o) noexcept = default; + + void swap(QBiPointer &other) noexcept { std::swap(ptr_value, other.ptr_value); } + + Q_NODISCARD_CTOR inline QBiPointer(T *); + Q_NODISCARD_CTOR inline QBiPointer(T2 *); + + inline bool isNull() const; + inline bool isT1() const; + inline bool isT2() const; + + inline bool flag() const; + inline void setFlag(); + inline void clearFlag(); + inline void setFlagValue(bool); + + inline QBiPointer<T, T2> &operator=(T *); + inline QBiPointer<T, T2> &operator=(T2 *); + + friend inline bool operator==(QBiPointer<T, T2> ptr1, QBiPointer<T, T2> ptr2) + { + if (ptr1.isNull() && ptr2.isNull()) + return true; + if (ptr1.isT1() && ptr2.isT1()) + return ptr1.asT1() == ptr2.asT1(); + if (ptr1.isT2() && ptr2.isT2()) + return ptr1.asT2() == ptr2.asT2(); + return false; + } + friend inline bool operator!=(QBiPointer<T, T2> ptr1, QBiPointer<T, T2> ptr2) + { + return !(ptr1 == ptr2); + } + + friend void swap(QBiPointer &lhs, QBiPointer &rhs) noexcept { lhs.swap(rhs); } + + inline T *asT1() const; + inline T2 *asT2() const; + + friend size_t qHash(const QBiPointer<T, T2> &ptr, size_t seed = 0) + { + return qHash(ptr.isNull() ? quintptr(0) : ptr.ptr_value, seed); + } + +private: + quintptr ptr_value = 0; + + static const quintptr FlagBit = 0x1; + static const quintptr Flag2Bit = 0x2; + static const quintptr FlagsMask = FlagBit | Flag2Bit; +}; + +template <typename...Ts> // can't use commas in macros +Q_DECLARE_TYPEINFO_BODY(QBiPointer<Ts...>, Q_PRIMITIVE_TYPE); + +template<typename T, typename T2> +QBiPointer<T, T2>::QBiPointer(T *v) +: ptr_value(quintptr(v)) +{ + Q_STATIC_ASSERT_X(QtPrivate::QFlagPointerAlignment<T>::Value >= 4, + "Type T does not have sufficient alignment"); + Q_ASSERT((quintptr(v) & FlagsMask) == 0); +} + +template<typename T, typename T2> +QBiPointer<T, T2>::QBiPointer(T2 *v) +: ptr_value(quintptr(v) | Flag2Bit) +{ + Q_STATIC_ASSERT_X(QtPrivate::QFlagPointerAlignment<T2>::Value >= 4, + "Type T2 does not have sufficient alignment"); + Q_ASSERT((quintptr(v) & FlagsMask) == 0); +} + +template<typename T, typename T2> +bool QBiPointer<T, T2>::isNull() const +{ + return 0 == (ptr_value & (~FlagsMask)); +} + +template<typename T, typename T2> +bool QBiPointer<T, T2>::isT1() const +{ + return !(ptr_value & Flag2Bit); +} + +template<typename T, typename T2> +bool QBiPointer<T, T2>::isT2() const +{ + return ptr_value & Flag2Bit; +} + +template<typename T, typename T2> +bool QBiPointer<T, T2>::flag() const +{ + return ptr_value & FlagBit; +} + +template<typename T, typename T2> +void QBiPointer<T, T2>::setFlag() +{ + ptr_value |= FlagBit; +} + +template<typename T, typename T2> +void QBiPointer<T, T2>::clearFlag() +{ + ptr_value &= ~FlagBit; +} + +template<typename T, typename T2> +void QBiPointer<T, T2>::setFlagValue(bool v) +{ + if (v) setFlag(); + else clearFlag(); +} + +template<typename T, typename T2> +QBiPointer<T, T2> &QBiPointer<T, T2>::operator=(T *o) +{ + Q_ASSERT((quintptr(o) & FlagsMask) == 0); + + ptr_value = quintptr(o) | (ptr_value & FlagBit); + return *this; +} + +template<typename T, typename T2> +QBiPointer<T, T2> &QBiPointer<T, T2>::operator=(T2 *o) +{ + Q_ASSERT((quintptr(o) & FlagsMask) == 0); + + ptr_value = quintptr(o) | (ptr_value & FlagBit) | Flag2Bit; + return *this; +} + +template<typename T, typename T2> +T *QBiPointer<T, T2>::asT1() const +{ + Q_ASSERT(isT1()); + return (T *)(ptr_value & ~FlagsMask); +} + +template<typename T, typename T2> +T2 *QBiPointer<T, T2>::asT2() const +{ + Q_ASSERT(isT2()); + return (T2 *)(ptr_value & ~FlagsMask); +} + +QT_END_NAMESPACE + +#endif // QBIPOINTER_P_H |