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Diffstat (limited to 'src/corelib/tools/qoffsetstringarray_p.h')
| -rw-r--r-- | src/corelib/tools/qoffsetstringarray_p.h | 198 |
1 files changed, 198 insertions, 0 deletions
diff --git a/src/corelib/tools/qoffsetstringarray_p.h b/src/corelib/tools/qoffsetstringarray_p.h new file mode 100644 index 0000000000..4dd9e9603b --- /dev/null +++ b/src/corelib/tools/qoffsetstringarray_p.h @@ -0,0 +1,198 @@ +/**************************************************************************** +** +** Copyright (C) 2018 The Qt Company Ltd. +** Contact: https://www.qt.io/licensing/ +** +** This file is part of the QtCore module of the Qt Toolkit. +** +** $QT_BEGIN_LICENSE:LGPL$ +** Commercial License Usage +** Licensees holding valid commercial Qt licenses may use this file in +** accordance with the commercial license agreement provided with the +** Software or, alternatively, in accordance with the terms contained in +** a written agreement between you and The Qt Company. For licensing terms +** and conditions see https://www.qt.io/terms-conditions. For further +** information use the contact form at https://www.qt.io/contact-us. +** +** GNU Lesser General Public License Usage +** Alternatively, this file may be used under the terms of the GNU Lesser +** General Public License version 3 as published by the Free Software +** Foundation and appearing in the file LICENSE.LGPL3 included in the +** packaging of this file. Please review the following information to +** ensure the GNU Lesser General Public License version 3 requirements +** will be met: https://www.gnu.org/licenses/lgpl-3.0.html. +** +** GNU General Public License Usage +** Alternatively, this file may be used under the terms of the GNU +** General Public License version 2.0 or (at your option) the GNU General +** Public license version 3 or any later version approved by the KDE Free +** Qt Foundation. The licenses are as published by the Free Software +** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3 +** included in the packaging of this file. Please review the following +** information to ensure the GNU General Public License requirements will +** be met: https://www.gnu.org/licenses/gpl-2.0.html and +** https://www.gnu.org/licenses/gpl-3.0.html. +** +** $QT_END_LICENSE$ +** +****************************************************************************/ + +#ifndef QOFFSETSTRINGARRAY_P_H +#define QOFFSETSTRINGARRAY_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 "private/qglobal_p.h" + +#include <tuple> +#include <array> + +QT_BEGIN_NAMESPACE + +namespace QtPrivate { +template<int N, int O, int I, int ... Idx> +struct OffsetSequenceHelper : OffsetSequenceHelper<N - 1, O + I, Idx..., O> { }; + +template<int Last, int I, int S, int ... Idx> +struct OffsetSequenceHelper<1, Last, I, S, Idx...> : IndexesList<Last + I, Idx..., Last> +{ + static const constexpr auto Length = Last + I; + using Type = typename std::conditional< + Last <= std::numeric_limits<quint8>::max(), + quint8, + typename std::conditional< + Last <= std::numeric_limits<quint16>::max(), + quint16, + int>::type + >::type; +}; + +template<int ... Idx> +struct OffsetSequence : OffsetSequenceHelper<sizeof ... (Idx), 0, Idx..., 0> { }; + +template<int N> +struct StaticString +{ + const char data[N]; +}; + + +template<> +struct StaticString<0> +{ + static constexpr int size() noexcept + { + return 0; + } +}; + +template<typename, typename> +struct StaticStringBuilder; + +template<int ... I1, int ... I2> +struct StaticStringBuilder<IndexesList<I1...>, IndexesList<I2...>> +{ + +QT_WARNING_PUSH +QT_WARNING_DISABLE_MSVC(4100) // The formal parameter is not referenced in the body of the function. + // The unreferenced parameter is ignored. + // It happens when 'rs' is StaticString<0> + template<int N1, int N2> + static constexpr StaticString<N1 + N2> concatenate( + const char (&ls)[N1], const StaticString<N2> &rs) noexcept + { + return StaticString<N1 + N2>{{ls[I1]..., rs.data[I2]...}}; + } +QT_WARNING_POP +}; + +template<int Sum> +constexpr StaticString<0> staticString() noexcept +{ + return StaticString<0>{}; +} + +QT_WARNING_PUSH +QT_WARNING_DISABLE_MSVC(4503) +template<int Sum, int I, int ... Ix> +constexpr StaticString<Sum> staticString(const char (&s)[I], const char (&...sx)[Ix]) noexcept +{ + return StaticStringBuilder< + makeIndexSequence<I>, + makeIndexSequence<Sum - I>>::concatenate(s, staticString<Sum - I>(sx...)); +} +QT_WARNING_POP +} // namespace QtPrivate + +template<typename T, int SizeString, int SizeOffsets> +class QOffsetStringArray +{ +public: + using Type = T; + + template<int ... Ox> + constexpr QOffsetStringArray(const QtPrivate::StaticString<SizeString> &str, + QtPrivate::IndexesList<SizeString, Ox...>) noexcept + : m_string(str), + m_offsets{Ox...} + { } + + constexpr inline const char *operator[](const int index) const noexcept + { + return m_string.data + m_offsets[qBound(int(0), index, SizeOffsets - 1)]; + } + + constexpr inline const char *at(const int index) const noexcept + { + return m_string.data + m_offsets[index]; + } + + constexpr inline const char *str() const { return m_string.data; } + constexpr inline const T *offsets() const { return m_offsets; } + constexpr inline int count() const { return SizeOffsets; }; + + static constexpr const auto sizeString = SizeString; + static constexpr const auto sizeOffsets = SizeOffsets; + +private: + QtPrivate::StaticString<SizeString> m_string; + const T m_offsets[SizeOffsets]; +}; + +template<typename T, int N, int ... Ox> +constexpr QOffsetStringArray<T, N, sizeof ... (Ox)> qOffsetStringArray( + const QtPrivate::StaticString<N> &string, + QtPrivate::IndexesList<N, Ox...> offsets) noexcept +{ + return QOffsetStringArray<T, N, sizeof ... (Ox)>( + string, + offsets); +} + +template<int ... Nx> +struct QOffsetStringArrayRet +{ + using Offsets = QtPrivate::OffsetSequence<Nx...>; + using Type = QOffsetStringArray<typename Offsets::Type, Offsets::Length, sizeof ... (Nx)>; +}; + +template<int ... Nx> +constexpr auto qOffsetStringArray(const char (&...strings)[Nx]) noexcept -> typename QOffsetStringArrayRet<Nx...>::Type +{ + using Offsets = QtPrivate::OffsetSequence<Nx...>; + return qOffsetStringArray<typename Offsets::Type>( + QtPrivate::staticString<Offsets::Length>(strings...), Offsets{}); +} + +QT_END_NAMESPACE + +#endif // QOFFSETSTRINGARRAY_P_H |