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qbytearrayview.h
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1// Copyright (C) 2021 The Qt Company Ltd.
2// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
3#ifndef QBYTEARRAYVIEW_H
4#define QBYTEARRAYVIEW_H
5
6#include <QtCore/qbytearrayalgorithms.h>
7#include <QtCore/qcompare.h>
8#include <QtCore/qcontainerfwd.h>
9#include <QtCore/qstringfwd.h>
10#include <QtCore/qarraydata.h>
11
12#include <string>
13#include <string_view>
14#include <QtCore/q20type_traits.h>
15
16QT_BEGIN_NAMESPACE
17
18namespace QtPrivate {
19
20template <typename Byte>
21struct IsCompatibleByteTypeHelper : std::false_type {};
22template <> struct IsCompatibleByteTypeHelper<char> : std::true_type {};
23template <> struct IsCompatibleByteTypeHelper<signed char> : std::true_type {};
24template <> struct IsCompatibleByteTypeHelper<unsigned char> : std::true_type {};
25template <> struct IsCompatibleByteTypeHelper<std::byte> : std::true_type {};
26
27template <typename Byte>
30
31template <typename Pointer>
32struct IsCompatibleByteArrayPointerHelper : std::false_type {};
33template <typename Byte>
36template<typename Pointer>
39
40template <typename T, typename Enable = void>
41struct IsContainerCompatibleWithQByteArrayView : std::false_type {};
42
43template <typename T>
44struct IsContainerCompatibleWithQByteArrayView<T, std::enable_if_t<
45 std::conjunction_v<
46 // lacking concepts and ranges, we accept any T whose std::data yields a suitable
47 // pointer ...
48 IsCompatibleByteArrayPointer<decltype(std::data(std::declval<const T &>()))>,
49 // ... and that has a suitable size ...
50 std::is_convertible<decltype(std::size(std::declval<const T &>())), qsizetype>,
51 // ... and it's a range as it defines an iterator-like API
52 IsCompatibleByteType<typename std::iterator_traits<decltype(
53 std::begin(std::declval<const T &>()))>::value_type>,
54 std::is_convertible<decltype(std::begin(std::declval<const T &>())
55 != std::end(std::declval<const T &>())),
56 bool>,
57
58 // This needs to be treated specially due to the empty vs null distinction
59 std::negation<std::is_same<std::decay_t<T>, QByteArray>>,
60
61 // We handle array literals specially for source compat reasons
62 std::negation<std::is_array<T>>,
63
64 // Don't make an accidental copy constructor
65 std::negation<std::is_same<std::decay_t<T>, QByteArrayView>>>>> : std::true_type {};
66
67// Used by QLatin1StringView too
68template <typename Char>
69static constexpr qsizetype lengthHelperPointer(const Char *data) noexcept
70{
71 // std::char_traits can only be used with one of the regular char types
72 // (char, char16_t, wchar_t, but not uchar or QChar), so we roll the loop
73 // out by ourselves.
74 qsizetype i = 0;
75 if (!data)
76 return i;
77 while (data[i] != Char(0))
78 ++i;
79 return i;
80}
81
82} // namespace QtPrivate
83
84class Q_CORE_EXPORT QByteArrayView
85{
86public:
87 typedef char storage_type;
88 typedef const char value_type;
89 typedef qptrdiff difference_type;
90 typedef qsizetype size_type;
91 typedef value_type &reference;
92 typedef value_type &const_reference;
93 typedef value_type *pointer;
94 typedef value_type *const_pointer;
95
96 typedef pointer iterator;
97 typedef const_pointer const_iterator;
98 typedef std::reverse_iterator<iterator> reverse_iterator;
99 typedef std::reverse_iterator<const_iterator> const_reverse_iterator;
100
101private:
102 template <typename Byte>
103 using if_compatible_byte =
104 typename std::enable_if_t<QtPrivate::IsCompatibleByteType<Byte>::value, bool>;
105
106 template <typename Pointer>
107 using if_compatible_pointer =
108 typename std::enable_if_t<QtPrivate::IsCompatibleByteArrayPointer<Pointer>::value,
109 bool>;
110
111 template <typename T>
112 using if_compatible_qbytearray_like =
113 typename std::enable_if_t<std::is_same_v<T, QByteArray>, bool>;
114
115 template <typename T>
116 using if_compatible_container =
117 typename std::enable_if_t<QtPrivate::IsContainerCompatibleWithQByteArrayView<T>::value,
118 bool>;
119
120 template <typename Container>
121 static constexpr qsizetype lengthHelperContainer(const Container &c) noexcept
122 {
123 return qsizetype(std::size(c));
124 }
125
126 static constexpr qsizetype lengthHelperCharArray(const char *data, size_t size) noexcept
127 {
128 const auto it = std::char_traits<char>::find(data, size, '\0');
129 const auto end = it ? it : std::next(data, size);
130 return qsizetype(std::distance(data, end));
131 }
132
133 template <typename Byte>
134 static const storage_type *castHelper(const Byte *data) noexcept
135 { return reinterpret_cast<const storage_type*>(data); }
136 static constexpr const storage_type *castHelper(const storage_type *data) noexcept
137 { return data; }
138
139public:
140 constexpr QByteArrayView() noexcept
141 : m_size(0), m_data(nullptr) {}
142 constexpr QByteArrayView(std::nullptr_t) noexcept
143 : QByteArrayView() {}
144
145 template <typename Byte, if_compatible_byte<Byte> = true>
146 constexpr QByteArrayView(const Byte *data, qsizetype len)
147 : m_size((Q_ASSERT(len >= 0), Q_ASSERT(data || !len), len)),
148 m_data(castHelper(data)) {}
149
150 template <typename Byte, if_compatible_byte<Byte> = true>
151 constexpr QByteArrayView(const Byte *first, const Byte *last)
152 : QByteArrayView(first, last - first) {}
153
154#ifdef Q_QDOC
155 template <typename Byte>
156 constexpr QByteArrayView(const Byte *data) noexcept;
157#else
158 template <typename Pointer, if_compatible_pointer<Pointer> = true>
159 constexpr QByteArrayView(const Pointer &data) noexcept
160 : QByteArrayView(
161 data, data ? QtPrivate::lengthHelperPointer(data) : 0) {}
162#endif
163
164#ifdef Q_QDOC
165 QByteArrayView(const QByteArray &data) noexcept;
166#else
167 template <typename ByteArray, if_compatible_qbytearray_like<ByteArray> = true>
168 QByteArrayView(const ByteArray &ba) noexcept
169 : QByteArrayView{ba.begin(), ba.size()} {}
170#endif
171
172 template <typename Container, if_compatible_container<Container> = true>
173 constexpr QByteArrayView(const Container &c) noexcept
174 : QByteArrayView(std::data(c), lengthHelperContainer(c)) {}
175 template <size_t Size>
176 constexpr QByteArrayView(const char (&data)[Size]) noexcept
177 : QByteArrayView(data, lengthHelperCharArray(data, Size)) {}
178
179 template <typename Byte, if_compatible_byte<Byte> = true>
180 constexpr QByteArrayView(const Byte (&data)[]) noexcept
181 : QByteArrayView(&*data) {} // decay to pointer
182
183#ifdef Q_QDOC
184 template <typename Byte, size_t Size>
185#else
186 template <typename Byte, size_t Size, if_compatible_byte<Byte> = true>
187#endif
188 [[nodiscard]] constexpr static QByteArrayView fromArray(const Byte (&data)[Size]) noexcept
189 { return QByteArrayView(data, Size); }
190 [[nodiscard]] inline QByteArray toByteArray() const; // defined in qbytearray.h
191
192 [[nodiscard]] constexpr qsizetype size() const noexcept { return m_size; }
193 [[nodiscard]] constexpr const_pointer data() const noexcept { return m_data; }
194 [[nodiscard]] constexpr const_pointer constData() const noexcept { return data(); }
195
196 [[nodiscard]] constexpr char operator[](qsizetype n) const
197 { verify(n, 1); return m_data[n]; }
198
199 //
200 // QByteArray API
201 //
202 [[nodiscard]] constexpr char at(qsizetype n) const { return (*this)[n]; }
203
204 [[nodiscard]] constexpr QByteArrayView first(qsizetype n) const
205 { verify(0, n); return sliced(0, n); }
206 [[nodiscard]] constexpr QByteArrayView last(qsizetype n) const
207 { verify(0, n); return sliced(size() - n, n); }
208 [[nodiscard]] constexpr QByteArrayView sliced(qsizetype pos) const
209 { verify(pos, 0); return QByteArrayView(data() + pos, size() - pos); }
210 [[nodiscard]] constexpr QByteArrayView sliced(qsizetype pos, qsizetype n) const
211 { verify(pos, n); return QByteArrayView(data() + pos, n); }
212
213 constexpr QByteArrayView &slice(qsizetype pos)
214 { *this = sliced(pos); return *this; }
215 constexpr QByteArrayView &slice(qsizetype pos, qsizetype n)
216 { *this = sliced(pos, n); return *this; }
217
218 [[nodiscard]] constexpr QByteArrayView chopped(qsizetype len) const
219 { verify(0, len); return sliced(0, size() - len); }
220
221 [[nodiscard]] constexpr QByteArrayView left(qsizetype n) const
222 { if (n < 0 || n > size()) n = size(); return QByteArrayView(data(), n); }
223 [[nodiscard]] constexpr QByteArrayView right(qsizetype n) const
224 { if (n < 0 || n > size()) n = size(); if (n < 0) n = 0; return QByteArrayView(data() + size() - n, n); }
225 [[nodiscard]] constexpr QByteArrayView mid(qsizetype pos, qsizetype n = -1) const
226 {
227 using namespace QtPrivate;
228 auto result = QContainerImplHelper::mid(size(), &pos, &n);
229 return result == QContainerImplHelper::Null ? QByteArrayView()
230 : QByteArrayView(m_data + pos, n);
231 }
232
233 constexpr void truncate(qsizetype n)
234 { verify(0, n); m_size = n; }
235 constexpr void chop(qsizetype n)
236 { verify(0, n); m_size -= n; }
237
238 // Defined in qbytearray.cpp:
239 [[nodiscard]] QByteArrayView trimmed() const noexcept
240 { return QtPrivate::trimmed(*this); }
241 [[nodiscard]] short toShort(bool *ok = nullptr, int base = 10) const
242 { return QtPrivate::toIntegral<short>(*this, ok, base); }
243 [[nodiscard]] ushort toUShort(bool *ok = nullptr, int base = 10) const
244 { return QtPrivate::toIntegral<ushort>(*this, ok, base); }
245 [[nodiscard]] int toInt(bool *ok = nullptr, int base = 10) const
246 { return QtPrivate::toIntegral<int>(*this, ok, base); }
247 [[nodiscard]] uint toUInt(bool *ok = nullptr, int base = 10) const
248 { return QtPrivate::toIntegral<uint>(*this, ok, base); }
249 [[nodiscard]] long toLong(bool *ok = nullptr, int base = 10) const
250 { return QtPrivate::toIntegral<long>(*this, ok, base); }
251 [[nodiscard]] ulong toULong(bool *ok = nullptr, int base = 10) const
252 { return QtPrivate::toIntegral<ulong>(*this, ok, base); }
253 [[nodiscard]] qlonglong toLongLong(bool *ok = nullptr, int base = 10) const
254 { return QtPrivate::toIntegral<qlonglong>(*this, ok, base); }
255 [[nodiscard]] qulonglong toULongLong(bool *ok = nullptr, int base = 10) const
256 { return QtPrivate::toIntegral<qulonglong>(*this, ok, base); }
257 [[nodiscard]] float toFloat(bool *ok = nullptr) const
258 {
259 const auto r = QtPrivate::toFloat(*this);
260 if (ok)
261 *ok = bool(r);
262 return r.value_or(0.0f);
263 }
264 [[nodiscard]] double toDouble(bool *ok = nullptr) const
265 {
266 const auto r = QtPrivate::toDouble(*this);
267 if (ok)
268 *ok = bool(r);
269 return r.value_or(0.0);
270 }
271
272 [[nodiscard]] bool startsWith(QByteArrayView other) const noexcept
273 { return QtPrivate::startsWith(*this, other); }
274 [[nodiscard]] constexpr bool startsWith(char c) const noexcept
275 { return !empty() && front() == c; }
276
277 [[nodiscard]] bool endsWith(QByteArrayView other) const noexcept
278 { return QtPrivate::endsWith(*this, other); }
279 [[nodiscard]] constexpr bool endsWith(char c) const noexcept
280 { return !empty() && back() == c; }
281
282 [[nodiscard]] qsizetype indexOf(QByteArrayView a, qsizetype from = 0) const noexcept
283 { return QtPrivate::findByteArray(*this, from, a); }
284 [[nodiscard]] qsizetype indexOf(char ch, qsizetype from = 0) const noexcept
285 { return QtPrivate::findByteArray(*this, from, ch); }
286
287 [[nodiscard]] bool contains(QByteArrayView a) const noexcept
288 { return indexOf(a) != qsizetype(-1); }
289 [[nodiscard]] bool contains(char c) const noexcept
290 { return indexOf(c) != qsizetype(-1); }
291
292 [[nodiscard]] qsizetype lastIndexOf(QByteArrayView a) const noexcept
293 { return lastIndexOf(a, size()); }
294 [[nodiscard]] qsizetype lastIndexOf(QByteArrayView a, qsizetype from) const noexcept
295 { return QtPrivate::lastIndexOf(*this, from, a); }
296 [[nodiscard]] qsizetype lastIndexOf(char ch, qsizetype from = -1) const noexcept
297 { return QtPrivate::lastIndexOf(*this, from, ch); }
298
299 [[nodiscard]] qsizetype count(QByteArrayView a) const noexcept
300 { return QtPrivate::count(*this, a); }
301 [[nodiscard]] qsizetype count(char ch) const noexcept
302 { return QtPrivate::count(*this, QByteArrayView(&ch, 1)); }
303
304 inline int compare(QByteArrayView a, Qt::CaseSensitivity cs = Qt::CaseSensitive) const noexcept;
305
306 [[nodiscard]] inline bool isValidUtf8() const noexcept { return QtPrivate::isValidUtf8(*this); }
307
308 //
309 // STL compatibility API:
310 //
311 [[nodiscard]] constexpr const_iterator begin() const noexcept { return data(); }
312 [[nodiscard]] constexpr const_iterator end() const noexcept { return data() + size(); }
313 [[nodiscard]] constexpr const_iterator cbegin() const noexcept { return begin(); }
314 [[nodiscard]] constexpr const_iterator cend() const noexcept { return end(); }
315 [[nodiscard]] constexpr const_reverse_iterator rbegin() const noexcept { return const_reverse_iterator(end()); }
316 [[nodiscard]] constexpr const_reverse_iterator rend() const noexcept { return const_reverse_iterator(begin()); }
317 [[nodiscard]] constexpr const_reverse_iterator crbegin() const noexcept { return rbegin(); }
318 [[nodiscard]] constexpr const_reverse_iterator crend() const noexcept { return rend(); }
319
320 [[nodiscard]] constexpr bool empty() const noexcept { return size() == 0; }
321 [[nodiscard]] constexpr char front() const { Q_ASSERT(!empty()); return m_data[0]; }
322 [[nodiscard]] constexpr char back() const { Q_ASSERT(!empty()); return m_data[m_size - 1]; }
323
324 [[nodiscard]] constexpr Q_IMPLICIT operator std::string_view() const noexcept
325 { return std::string_view(m_data, size_t(m_size)); }
326
327 [[nodiscard]] constexpr qsizetype max_size() const noexcept { return maxSize(); }
328
329 //
330 // Qt compatibility API:
331 //
332 [[nodiscard]] constexpr bool isNull() const noexcept { return !m_data; }
333 [[nodiscard]] constexpr bool isEmpty() const noexcept { return empty(); }
334 [[nodiscard]] constexpr qsizetype length() const noexcept
335 { return size(); }
336 [[nodiscard]] constexpr char first() const { return front(); }
337 [[nodiscard]] constexpr char last() const { return back(); }
338
339 [[nodiscard]] static constexpr qsizetype maxSize() noexcept
340 {
341 // -1 to deal with the pointer one-past-the-end;
342 return QtPrivate::MaxAllocSize - 1;
343 }
344
345private:
346 Q_ALWAYS_INLINE constexpr void verify([[maybe_unused]] qsizetype pos = 0,
347 [[maybe_unused]] qsizetype n = 1) const
348 {
349 Q_ASSERT(pos >= 0);
350 Q_ASSERT(pos <= size());
351 Q_ASSERT(n >= 0);
352 Q_ASSERT(n <= size() - pos);
353 }
354
355 friend bool
356 comparesEqual(const QByteArrayView &lhs, const QByteArrayView &rhs) noexcept
357 {
358 return lhs.size() == rhs.size()
359 && (!lhs.size() || memcmp(lhs.data(), rhs.data(), lhs.size()) == 0);
360 }
361 friend Qt::strong_ordering
362 compareThreeWay(const QByteArrayView &lhs, const QByteArrayView &rhs) noexcept
363 {
364 const int res = QtPrivate::compareMemory(lhs, rhs);
365 return Qt::compareThreeWay(res, 0);
366 }
367 Q_DECLARE_STRONGLY_ORDERED(QByteArrayView)
368
369 friend bool comparesEqual(const QByteArrayView &lhs, const char *rhs) noexcept
370 { return comparesEqual(lhs, QByteArrayView(rhs)); }
371 friend Qt::strong_ordering
372 compareThreeWay(const QByteArrayView &lhs, const char *rhs) noexcept
373 { return compareThreeWay(lhs, QByteArrayView(rhs)); }
374 Q_DECLARE_STRONGLY_ORDERED(QByteArrayView, const char *)
375
376 // defined in qstring.cpp
377 friend Q_CORE_EXPORT bool
378 comparesEqual(const QByteArrayView &lhs, const QChar &rhs) noexcept;
379 friend Q_CORE_EXPORT Qt::strong_ordering
380 compareThreeWay(const QByteArrayView &lhs, const QChar &rhs) noexcept;
381 friend Q_CORE_EXPORT bool
382 comparesEqual(const QByteArrayView &lhs, char16_t rhs) noexcept;
383 friend Q_CORE_EXPORT Qt::strong_ordering
384 compareThreeWay(const QByteArrayView &lhs, char16_t rhs) noexcept;
385#if !defined(QT_NO_CAST_FROM_ASCII) && !defined(QT_RESTRICTED_CAST_FROM_ASCII)
386 Q_DECLARE_STRONGLY_ORDERED(QByteArrayView, QChar, QT_ASCII_CAST_WARN)
387 Q_DECLARE_STRONGLY_ORDERED(QByteArrayView, char16_t, QT_ASCII_CAST_WARN)
388#endif // !defined(QT_NO_CAST_FROM_ASCII) && !defined(QT_RESTRICTED_CAST_FROM_ASCII)
389
390 qsizetype m_size;
391 const storage_type *m_data;
392};
393Q_DECLARE_TYPEINFO(QByteArrayView, Q_PRIMITIVE_TYPE);
394
395template<typename QByteArrayLike,
396 std::enable_if_t<std::is_same_v<QByteArrayLike, QByteArray>, bool> = true>
397[[nodiscard]] inline QByteArrayView qToByteArrayViewIgnoringNull(const QByteArrayLike &b) noexcept
398{ return QByteArrayView(b.begin(), b.size()); }
399
400inline int QByteArrayView::compare(QByteArrayView a, Qt::CaseSensitivity cs) const noexcept
401{
402 return cs == Qt::CaseSensitive ? QtPrivate::compareMemory(*this, a) :
403 qstrnicmp(data(), size(), a.data(), a.size());
404}
405
406#if QT_DEPRECATED_SINCE(6, 0)
407QT_DEPRECATED_VERSION_X_6_0("Use the QByteArrayView overload.")
408inline quint16 qChecksum(const char *s, qsizetype len,
409 Qt::ChecksumType standard = Qt::ChecksumIso3309)
410{ return qChecksum(QByteArrayView(s, len), standard); }
411#endif
412
413qsizetype QtPrivate::findByteArray(QByteArrayView haystack, qsizetype from, char needle) noexcept
414{
415 if (from < 0)
416 from = qMax(from + haystack.size(), qsizetype(0));
417 if (from < haystack.size()) {
418 const char *const b = haystack.data();
419 if (const auto n = static_cast<const char *>(
420 memchr(b + from, needle, static_cast<size_t>(haystack.size() - from)))) {
421 return n - b;
422 }
423 }
424 return -1;
425}
426
427qsizetype QtPrivate::lastIndexOf(QByteArrayView haystack, qsizetype from, uchar needle) noexcept
428{
429 if (from < 0)
430 from = qMax(from + haystack.size(), qsizetype(0));
431 else
432 from = qMin(from, haystack.size() - 1);
433
434 const char *const b = haystack.data();
435 const void *n = b ? qmemrchr(b, needle, from + 1) : nullptr;
436 return n ? static_cast<const char *>(n) - b : -1;
437}
438
439QT_END_NAMESPACE
440
441#endif // QBYTEARRAYVIEW_H
QDataStream
\inmodule QtCore\reentrant
Definition qdatastream.h:49
QT_BEGIN_NAMESPACE
Combined button and popup list for selecting options.
Definition qstandardpaths_haiku.cpp:21
QtPrivate::asString
QString && asString(QString &&s)
Definition qstring.h:1662
QtPrivate::qStringLikeToArg
constexpr QAnyStringArg qStringLikeToArg(QAnyStringView s) noexcept
Definition qstring.h:1723
QtPrivate::asString
const QString & asString(const QString &s)
Definition qstring.h:1661
QtPrivate::lengthHelperPointer
static constexpr qsizetype lengthHelperPointer(const Char *data) noexcept
Definition qbytearrayview.h:69
QtPrivate::isLatin1
constexpr bool isLatin1(QLatin1StringView s) noexcept
Definition qstring.h:78
Qt::Literals::StringLiterals::operator""_s
QString operator""_s(const char16_t *str, size_t size) noexcept
Definition qstring.h:1769
Qt
Definition qcompare.h:76
qToByteArrayViewIgnoringNull
QByteArrayView qToByteArrayViewIgnoringNull(const QByteArrayLike &b) noexcept
Definition qbytearrayview.h:397
Q_DECLARE_TYPEINFO
Q_DECLARE_TYPEINFO(QByteArrayView, Q_PRIMITIVE_TYPE)
__has_cpp_attribute
#define __has_cpp_attribute(x)
Definition qcompilerdetection.h:442
Q_LOGGING_CATEGORY
Q_LOGGING_CATEGORY(lcEventDispatcher, "qt.eventdispatcher")
qt_int_sqrt
Q_CORE_EXPORT Q_DECL_CONST_FUNCTION unsigned int qt_int_sqrt(unsigned int n)
\inmodule QtCore \title Global Qt Declarations
Definition qglobal.cpp:99
operator+
QString operator+(const QString &s1, QChar s2)
Definition qstring.h:1543
operator+
QString operator+(QString &&lhs, const QString &rhs)
Definition qstring.h:1541
erase_if
qsizetype erase_if(QString &s, Predicate pred)
Definition qstring.h:1761
operator+
QString operator+(QString &&lhs, QChar rhs)
Definition qstring.h:1545
operator+
QString operator+(QChar s1, const QString &s2)
Definition qstring.h:1547
operator+
QString operator+(const QString &s1, const QString &s2)
Definition qstring.h:1539
erase
qsizetype erase(QString &s, const T &t)
Definition qstring.h:1755
QInternal_CallBackTable
Definition qglobal.cpp:127
QInternal_CallBackTable::callbacks
QList< QList< qInternalCallback > > callbacks
Definition qglobal.cpp:128
QtPrivate::QAnyStringArg::QAnyStringArg
constexpr QAnyStringArg(QAnyStringView v) noexcept
Definition qstring.h:1707
QtPrivate::QAnyStringArg::string
QAnyStringView string
Definition qstring.h:1705
QtPrivate::QLatin1StringArg::string
QLatin1StringView string
Definition qstring.h:1699
QtPrivate::QLatin1StringArg::QLatin1StringArg
constexpr QLatin1StringArg(QLatin1StringView v) noexcept
Definition qstring.h:1701
QtPrivate::QStringViewArg::QStringViewArg
constexpr QStringViewArg(QStringView v) noexcept
Definition qstring.h:1695