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40
41#ifndef QARRAYDATA_H
42#define QARRAYDATA_H
43
44#include <QtCore/qpair.h>
45#include <QtCore/qatomic.h>
46#include <string.h>
47
48QT_BEGIN_NAMESPACE
49
50template <class T> struct QTypedArrayData;
51
52struct QArrayData
53{
54 enum AllocationOption {
55 Grow,
56 KeepSize
57 };
58
59 enum GrowthPosition {
60 GrowsAtEnd,
61 GrowsAtBeginning
62 };
63
64 enum ArrayOption {
65 ArrayOptionDefault = 0,
66 CapacityReserved = 0x1 //!< the capacity was reserved by the user, try to keep it
67 };
68 Q_DECLARE_FLAGS(ArrayOptions, ArrayOption)
69
70 QBasicAtomicInt ref_;
71 uint flags;
72 qsizetype alloc;
73
74 qsizetype allocatedCapacity() noexcept
75 {
76 return alloc;
77 }
78
79 qsizetype constAllocatedCapacity() const noexcept
80 {
81 return alloc;
82 }
83
84 /// Returns true if sharing took place
85 bool ref() noexcept
86 {
87 ref_.ref();
88 return true;
89 }
90
91 /// Returns false if deallocation is necessary
92 bool deref() noexcept
93 {
94 return ref_.deref();
95 }
96
97 bool isShared() const noexcept
98 {
99 return ref_.loadRelaxed() != 1;
100 }
101
102 // Returns true if a detach is necessary before modifying the data
103 // This method is intentionally not const: if you want to know whether
104 // detaching is necessary, you should be in a non-const function already
105 bool needsDetach() const noexcept
106 {
107 return ref_.loadRelaxed() > 1;
108 }
109
110 qsizetype detachCapacity(qsizetype newSize) const noexcept
111 {
112 if (flags & CapacityReserved && newSize < constAllocatedCapacity())
113 return constAllocatedCapacity();
114 return newSize;
115 }
116
117 [[nodiscard]]
118#if defined(Q_CC_GNU)
119 __attribute__((__malloc__))
120#endif
121 static Q_CORE_EXPORT void *allocate(QArrayData **pdata, qsizetype objectSize, qsizetype alignment,
122 qsizetype capacity, AllocationOption option = QArrayData::KeepSize) noexcept;
123 [[nodiscard]] static Q_CORE_EXPORT QPair<QArrayData *, void *> reallocateUnaligned(QArrayData *data, void *dataPointer,
124 qsizetype objectSize, qsizetype newCapacity, AllocationOption option) noexcept;
125 static Q_CORE_EXPORT void deallocate(QArrayData *data, qsizetype objectSize,
126 qsizetype alignment) noexcept;
127};
128
129Q_DECLARE_OPERATORS_FOR_FLAGS(QArrayData::ArrayOptions)
130
131template <class T>
132struct QTypedArrayData
133 : QArrayData
134{
135 struct AlignmentDummy { QArrayData header; T data; };
136
137 [[nodiscard]] static QPair<QTypedArrayData *, T *> allocate(qsizetype capacity, AllocationOption option = QArrayData::KeepSize)
138 {
139 static_assert(sizeof(QTypedArrayData) == sizeof(QArrayData));
140 QArrayData *d;
141 void *result = QArrayData::allocate(&d, sizeof(T), alignof(AlignmentDummy), capacity, option);
142#if __has_builtin(__builtin_assume_aligned)
143 result = __builtin_assume_aligned(result, Q_ALIGNOF(AlignmentDummy));
144#endif
145 return qMakePair(static_cast<QTypedArrayData *>(d), static_cast<T *>(result));
146 }
147
148 static QPair<QTypedArrayData *, T *>
149 reallocateUnaligned(QTypedArrayData *data, T *dataPointer, qsizetype capacity, AllocationOption option)
150 {
151 static_assert(sizeof(QTypedArrayData) == sizeof(QArrayData));
152 QPair<QArrayData *, void *> pair =
153 QArrayData::reallocateUnaligned(data, dataPointer, sizeof(T), capacity, option);
154 return qMakePair(static_cast<QTypedArrayData *>(pair.first), static_cast<T *>(pair.second));
155 }
156
157 static void deallocate(QArrayData *data) noexcept
158 {
159 static_assert(sizeof(QTypedArrayData) == sizeof(QArrayData));
160 QArrayData::deallocate(data, sizeof(T), alignof(AlignmentDummy));
161 }
162
163 static T *dataStart(QArrayData *data, qsizetype alignment) noexcept
164 {
165 // Alignment is a power of two
166 Q_ASSERT(alignment >= qsizetype(alignof(QArrayData)) && !(alignment & (alignment - 1)));
167 void *start = reinterpret_cast<void *>(
168 (quintptr(data) + sizeof(QArrayData) + alignment - 1) & ~(alignment - 1));
169 return static_cast<T *>(start);
170 }
171};
172
173namespace QtPrivate {
174struct Q_CORE_EXPORT QContainerImplHelper
175{
176 enum CutResult { Null, Empty, Full, Subset };
177 static constexpr CutResult mid(qsizetype originalLength, qsizetype *_position, qsizetype *_length)
178 {
179 qsizetype &position = *_position;
180 qsizetype &length = *_length;
181 if (position > originalLength) {
182 position = 0;
183 length = 0;
184 return Null;
185 }
186
187 if (position < 0) {
188 if (length < 0 || length + position >= originalLength) {
189 position = 0;
190 length = originalLength;
191 return Full;
192 }
193 if (length + position <= 0) {
194 position = length = 0;
195 return Null;
196 }
197 length += position;
198 position = 0;
199 } else if (size_t(length) > size_t(originalLength - position)) {
200 length = originalLength - position;
201 }
202
203 if (position == 0 && length == originalLength)
204 return Full;
205
206 return length > 0 ? Subset : Empty;
207 }
208};
209}
210
211QT_END_NAMESPACE
212
213#endif // include guard
214