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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
59QT_BEGIN_NAMESPACE
60
61namespace QtPrivate {
62template<int N, int O, int I, int ... Idx>
63struct OffsetSequenceHelper : OffsetSequenceHelper<N - 1, O + I, Idx..., O> { };
64
65template<int Last, int I, int S, int ... Idx>
66struct OffsetSequenceHelper<1, Last, I, S, Idx...> : IndexesList<Last + I, Idx..., Last>
67{
68 static const constexpr auto Length = Last + I;
69 using Type = typename std::conditional<
70 Last <= std::numeric_limits<quint8>::max(),
71 quint8,
72 typename std::conditional<
73 Last <= std::numeric_limits<quint16>::max(),
74 quint16,
75 int>::type
76 >::type;
77};
78
79template<int ... Idx>
80struct OffsetSequence : OffsetSequenceHelper<sizeof ... (Idx), 0, Idx..., 0> { };
81
82template<int N>
83struct StaticString
84{
85 const char data[N];
86};
87
88
89template<>
90struct StaticString<0>
91{
92 static constexpr int size() noexcept
93 {
94 return 0;
95 }
96};
97
98template<typename, typename>
99struct StaticStringBuilder;
100
101template<int ... I1, int ... I2>
102struct StaticStringBuilder<IndexesList<I1...>, IndexesList<I2...>>
103{
104
105QT_WARNING_PUSH
106QT_WARNING_DISABLE_MSVC(4100) // The formal parameter is not referenced in the body of the function.
107 // The unreferenced parameter is ignored.
108 // It happens when 'rs' is StaticString<0>
109 template<int N1, int N2>
110 static constexpr StaticString<N1 + N2> concatenate(
111 const char (&ls)[N1], const StaticString<N2> &rs) noexcept
112 {
113 return StaticString<N1 + N2>{{ls[I1]..., rs.data[I2]...}};
114 }
115QT_WARNING_POP
116};
117
118template<int Sum>
119constexpr StaticString<0> staticString() noexcept
120{
121 return StaticString<0>{};
122}
123
124QT_WARNING_PUSH
125QT_WARNING_DISABLE_MSVC(4503)
126template<int Sum, int I, int ... Ix>
127constexpr StaticString<Sum> staticString(const char (&s)[I], const char (&...sx)[Ix]) noexcept
128{
129 return StaticStringBuilder<
130 makeIndexSequence<I>,
131 makeIndexSequence<Sum - I>>::concatenate(s, staticString<Sum - I>(sx...));
132}
133QT_WARNING_POP
134} // namespace QtPrivate
135
136template<typename T, int SizeString, int SizeOffsets>
137class QOffsetStringArray
138{
139public:
140 using Type = T;
141
142 template<int ... Ox>
143 constexpr QOffsetStringArray(const QtPrivate::StaticString<SizeString> &str,
144 QtPrivate::IndexesList<SizeString, Ox...>) noexcept
145 : m_string(str),
146 m_offsets{Ox...}
147 { }
148
149 constexpr inline const char *operator[](const int index) const noexcept
150 {
151 return m_string.data + m_offsets[qBound(int(0), index, SizeOffsets - 1)];
152 }
153
154 constexpr inline const char *at(const int index) const noexcept
155 {
156 return m_string.data + m_offsets[index];
157 }
158
159 constexpr inline const char *str() const { return m_string.data; }
160 constexpr inline const T *offsets() const { return m_offsets; }
161 constexpr inline int count() const { return SizeOffsets; };
162
163 static constexpr const auto sizeString = SizeString;
164 static constexpr const auto sizeOffsets = SizeOffsets;
165
166private:
167 QtPrivate::StaticString<SizeString> m_string;
168 const T m_offsets[SizeOffsets];
169};
170
171template<typename T, int N, int ... Ox>
172constexpr QOffsetStringArray<T, N, sizeof ... (Ox)> qOffsetStringArray(
173 const QtPrivate::StaticString<N> &string,
174 QtPrivate::IndexesList<N, Ox...> offsets) noexcept
175{
176 return QOffsetStringArray<T, N, sizeof ... (Ox)>(
177 string,
178 offsets);
179}
180
181template<int ... Nx>
182struct QOffsetStringArrayRet
183{
184 using Offsets = QtPrivate::OffsetSequence<Nx...>;
185 using Type = QOffsetStringArray<typename Offsets::Type, Offsets::Length, sizeof ... (Nx)>;
186};
187
188template<int ... Nx>
189constexpr auto qOffsetStringArray(const char (&...strings)[Nx]) noexcept -> typename QOffsetStringArrayRet<Nx...>::Type
190{
191 using Offsets = QtPrivate::OffsetSequence<Nx...>;
192 return qOffsetStringArray<typename Offsets::Type>(
193 QtPrivate::staticString<Offsets::Length>(strings...), Offsets{});
194}
195
196QT_END_NAMESPACE
197
198#endif // QOFFSETSTRINGARRAY_P_H
199