1 /**************************************************************************** 2 ** 3 ** Copyright (C) 2018 The Qt Company Ltd. 4 ** Contact: https://www.qt.io/licensing/ 5 ** 6 ** This file is part of the QtCore module of the Qt Toolkit. 7 ** 8 ** $QT_BEGIN_LICENSE:LGPL$ 9 ** Commercial License Usage 10 ** Licensees holding valid commercial Qt licenses may use this file in 11 ** accordance with the commercial license agreement provided with the 12 ** Software or, alternatively, in accordance with the terms contained in 13 ** a written agreement between you and The Qt Company. For licensing terms 14 ** and conditions see https://www.qt.io/terms-conditions. For further 15 ** information use the contact form at https://www.qt.io/contact-us. 16 ** 17 ** GNU Lesser General Public License Usage 18 ** Alternatively, this file may be used under the terms of the GNU Lesser 19 ** General Public License version 3 as published by the Free Software 20 ** Foundation and appearing in the file LICENSE.LGPL3 included in the 21 ** packaging of this file. Please review the following information to 22 ** ensure the GNU Lesser General Public License version 3 requirements 23 ** will be met: https://www.gnu.org/licenses/lgpl-3.0.html. 24 ** 25 ** GNU General Public License Usage 26 ** Alternatively, this file may be used under the terms of the GNU 27 ** General Public License version 2.0 or (at your option) the GNU General 28 ** Public license version 3 or any later version approved by the KDE Free 29 ** Qt Foundation. The licenses are as published by the Free Software 30 ** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3 31 ** included in the packaging of this file. Please review the following 32 ** information to ensure the GNU General Public License requirements will 33 ** be met: https://www.gnu.org/licenses/gpl-2.0.html and 34 ** https://www.gnu.org/licenses/gpl-3.0.html. 35 ** 36 ** $QT_END_LICENSE$ 37 ** 38 ****************************************************************************/ 39 40 #ifndef QOFFSETSTRINGARRAY_P_H 41 #define QOFFSETSTRINGARRAY_P_H 42 43 // 44 // W A R N I N G 45 // ------------- 46 // 47 // This file is not part of the Qt API. It exists purely as an 48 // implementation detail. This header file may change from version to 49 // version without notice, or even be removed. 50 // 51 // We mean it. 52 // 53 54 #include "private/qglobal_p.h" 55 56 #include <tuple> 57 #include <array> 58 #include <limits> 59 60 QT_BEGIN_NAMESPACE 61 62 namespace QtPrivate { 63 template<int N, int O, int I, int ... Idx> 64 struct OffsetSequenceHelper : OffsetSequenceHelper<N - 1, O + I, Idx..., O> { }; 65 66 template<int Last, int I, int S, int ... Idx> 67 struct OffsetSequenceHelper<1, Last, I, S, Idx...> : IndexesList<Last + I, Idx..., Last> 68 { 69 static const constexpr auto Length = Last + I; 70 using Type = typename std::conditional< 71 Last <= std::numeric_limits<quint8>::max(), 72 quint8, 73 typename std::conditional< 74 Last <= std::numeric_limits<quint16>::max(), 75 quint16, 76 int>::type 77 >::type; 78 }; 79 80 template<int ... Idx> 81 struct OffsetSequence : OffsetSequenceHelper<sizeof ... (Idx), 0, Idx..., 0> { }; 82 83 template<int N> 84 struct StaticString 85 { 86 const char data[N]; 87 }; 88 89 90 template<> 91 struct StaticString<0> 92 { 93 static constexpr int size() noexcept 94 { 95 return 0; 96 } 97 }; 98 99 template<typename, typename> 100 struct StaticStringBuilder; 101 102 template<int ... I1, int ... I2> 103 struct StaticStringBuilder<IndexesList<I1...>, IndexesList<I2...>> 104 { 105 106 QT_WARNING_PUSH 107 QT_WARNING_DISABLE_MSVC(4100) // The formal parameter is not referenced in the body of the function. 108 // The unreferenced parameter is ignored. 109 // It happens when 'rs' is StaticString<0> 110 template<int N1, int N2> 111 static constexpr StaticString<N1 + N2> concatenate( 112 const char (&ls)[N1], const StaticString<N2> &rs) noexcept 113 { 114 return StaticString<N1 + N2>{{ls[I1]..., rs.data[I2]...}}; 115 } 116 QT_WARNING_POP 117 }; 118 119 template<int Sum> 120 constexpr StaticString<0> staticString() noexcept 121 { 122 return StaticString<0>{}; 123 } 124 125 QT_WARNING_PUSH 126 QT_WARNING_DISABLE_MSVC(4503) 127 template<int Sum, int I, int ... Ix> 128 constexpr StaticString<Sum> staticString(const char (&s)[I], const char (&...sx)[Ix]) noexcept 129 { 130 return StaticStringBuilder< 131 makeIndexSequence<I>, 132 makeIndexSequence<Sum - I>>::concatenate(s, staticString<Sum - I>(sx...)); 133 } 134 QT_WARNING_POP 135 } // namespace QtPrivate 136 137 template<typename T, int SizeString, int SizeOffsets> 138 class QOffsetStringArray 139 { 140 public: 141 using Type = T; 142 143 template<int ... Ox> 144 constexpr QOffsetStringArray(const QtPrivate::StaticString<SizeString> &str, 145 QtPrivate::IndexesList<SizeString, Ox...>) noexcept 146 : m_string(str), 147 m_offsets{Ox...} 148 { } 149 150 constexpr inline const char *operator[](const int index) const noexcept 151 { 152 return m_string.data + m_offsets[qBound(int(0), index, SizeOffsets - 1)]; 153 } 154 155 constexpr inline const char *at(const int index) const noexcept 156 { 157 return m_string.data + m_offsets[index]; 158 } 159 160 constexpr inline const char *str() const { return m_string.data; } 161 constexpr inline const T *offsets() const { return m_offsets; } 162 constexpr inline int count() const { return SizeOffsets; }; 163 164 static constexpr const auto sizeString = SizeString; 165 static constexpr const auto sizeOffsets = SizeOffsets; 166 167 private: 168 QtPrivate::StaticString<SizeString> m_string; 169 const T m_offsets[SizeOffsets]; 170 }; 171 172 template<typename T, int N, int ... Ox> 173 constexpr QOffsetStringArray<T, N, sizeof ... (Ox)> qOffsetStringArray( 174 const QtPrivate::StaticString<N> &string, 175 QtPrivate::IndexesList<N, Ox...> offsets) noexcept 176 { 177 return QOffsetStringArray<T, N, sizeof ... (Ox)>( 178 string, 179 offsets); 180 } 181 182 template<int ... Nx> 183 struct QOffsetStringArrayRet 184 { 185 using Offsets = QtPrivate::OffsetSequence<Nx...>; 186 using Type = QOffsetStringArray<typename Offsets::Type, Offsets::Length, sizeof ... (Nx)>; 187 }; 188 189 template<int ... Nx> 190 constexpr auto qOffsetStringArray(const char (&...strings)[Nx]) noexcept -> typename QOffsetStringArrayRet<Nx...>::Type 191 { 192 using Offsets = QtPrivate::OffsetSequence<Nx...>; 193 return qOffsetStringArray<typename Offsets::Type>( 194 QtPrivate::staticString<Offsets::Length>(strings...), Offsets{}); 195 } 196 197 QT_END_NAMESPACE 198 199 #endif // QOFFSETSTRINGARRAY_P_H 200