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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#include <limits>
59
60QT_BEGIN_NAMESPACE
61
62namespace QtPrivate {
63template<int N, int O, int I, int ... Idx>
64struct OffsetSequenceHelper : OffsetSequenceHelper<N - 1, O + I, Idx..., O> { };
65
66template<int Last, int I, int S, int ... Idx>
67struct 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
80template<int ... Idx>
81struct OffsetSequence : OffsetSequenceHelper<sizeof ... (Idx), 0, Idx..., 0> { };
82
83template<int N>
84struct StaticString
85{
86 const char data[N];
87};
88
89
90template<>
91struct StaticString<0>
92{
93 static constexpr int size() noexcept
94 {
95 return 0;
96 }
97};
98
99template<typename, typename>
100struct StaticStringBuilder;
101
102template<int ... I1, int ... I2>
103struct StaticStringBuilder<IndexesList<I1...>, IndexesList<I2...>>
104{
105
106QT_WARNING_PUSH
107QT_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 }
116QT_WARNING_POP
117};
118
119template<int Sum>
120constexpr StaticString<0> staticString() noexcept
121{
122 return StaticString<0>{};
123}
124
125QT_WARNING_PUSH
126QT_WARNING_DISABLE_MSVC(4503)
127template<int Sum, int I, int ... Ix>
128constexpr 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}
134QT_WARNING_POP
135} // namespace QtPrivate
136
137template<typename T, int SizeString, int SizeOffsets>
138class QOffsetStringArray
139{
140public:
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(min: int(0), val: index, max: 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
167private:
168 QtPrivate::StaticString<SizeString> m_string;
169 const T m_offsets[SizeOffsets];
170};
171
172template<typename T, int N, int ... Ox>
173constexpr 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
182template<int ... Nx>
183struct QOffsetStringArrayRet
184{
185 using Offsets = QtPrivate::OffsetSequence<Nx...>;
186 using Type = QOffsetStringArray<typename Offsets::Type, Offsets::Length, sizeof ... (Nx)>;
187};
188
189template<int ... Nx>
190constexpr 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
197QT_END_NAMESPACE
198
199#endif // QOFFSETSTRINGARRAY_P_H
200

source code of qtbase/src/corelib/tools/qoffsetstringarray_p.h