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 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406  /**************************************************************************** ** ** Copyright (C) 2020 Klarälvdalens Datakonsult AB, a KDAB Group company, info@kdab.com, author Marc Mutz ** Contact: https://www.qt.io/licensing/ ** ** This file is part of the documentation of the Qt Toolkit. ** ** $QT_BEGIN_LICENSE:FDL$ ** Commercial License Usage ** Licensees holding valid commercial Qt licenses may use this file in ** accordance with the commercial license agreement provided with the ** Software or, alternatively, in accordance with the terms contained in ** a written agreement between you and The Qt Company. For licensing terms ** and conditions see https://www.qt.io/terms-conditions. For further ** information use the contact form at https://www.qt.io/contact-us. ** ** GNU Free Documentation License Usage ** Alternatively, this file may be used under the terms of the GNU Free ** Documentation License version 1.3 as published by the Free Software ** Foundation and appearing in the file included in the packaging of ** this file. Please review the following information to ensure ** the GNU Free Documentation License version 1.3 requirements ** will be met: https://www.gnu.org/licenses/fdl-1.3.html. ** $QT_END_LICENSE$ ** ****************************************************************************/ /*! \class QAnyStringView \inmodule QtCore \since 6.0 \brief The QAnyStringView class provides a unified view on Latin-1, UTF-8, or UTF-16 strings with a read-only subset of the QString API. \reentrant \ingroup tools \ingroup string-processing A QAnyStringView references a contiguous portion of a string it does not own. It acts as an interface type to all kinds of strings, without the need to construct a QString first. Unlike QStringView and QUtf8StringView, QAnyStringView can hold strings of any of the following encodings: UTF-8, UTF-16, and Latin-1. The latter is supported to keep old source working efficiently. It is expected that by Qt 7, the Latin-1 support will be removed. The string may be represented as an array (or an array-compatible data-structure such as QString, std::basic_string, etc.) of \c char, \c char8_t, QChar, \c ushort, \c char16_t or (on platforms, such as Windows, where it is a 16-bit type) \c wchar_t. QAnyStringView is designed as an interface type; its main use-case is as a function parameter type. When QAnyStringViews are used as automatic variables or data members, care must be taken to ensure that the referenced string data (for example, owned by a QString) outlives the QAnyStringView on all code paths, lest the string view ends up referencing deleted data. When used as an interface type, QAnyStringView allows a single function to accept a wide variety of string data sources. One function accepting QAnyStringView thus replaces five function overloads (taking QString, \c{(const QChar*, int)}, QUtf8StringView, QLatin1String (but see above), and QChar), while at the same time enabling even more string data sources to be passed to the function, such as \c{u8"Hello World"}, a \c char8_t string literal. Like elsewhere in Qt, QAnyStringView assumes \c char data is encoded in UTF-8, unless it is presented as a QLatin1String. QAnyStringViews should be passed by value, not by reference-to-const: \snippet code/src_corelib_text_qanystringview.cpp 0 QAnyStringView can also be used as the return value of a function, but this is not recommended. QUtf8StringView or QStringView are better suited as function return values. If you call a function returning QAnyStringView, take extra care to not keep the QAnyStringView around longer than the function promises to keep the referenced string data alive. If in doubt, obtain a strong reference to the data by calling toString() to convert the QAnyStringView into a QString. QAnyStringView is a \e{Literal Type}. \section Compatible Character Types QAnyStringView accepts strings over a variety of character types: \list \li \c char (both signed and unsigned) \li \c char8_t (C++20 only) \li \c char16_t \li \c wchar_t (where it's a 16-bit type, e.g. Windows) \li \c ushort \li \c QChar \endlist The 8-bit character types are interpreted as UTF-8 data (except when presented as a QLatin1String) while the 16-bit character types are interpreted as UTF-16 data in host byte order (the same as QString). \section Sizes and Sub-Strings All sizes and positions in QAnyStringView functions are in the encoding's code points (that is, UTF-16 surrogate pairs count as two for the purposes of these functions, the same as in QString, and UTF-8 multibyte sequences count as two, three or four, depending on their length). \sa QUtf8StringView, QStringView */ /*! \typedef QStringView::difference_type Alias for \c{std::ptrdiff_t}. Provided for compatibility with the STL. */ /*! \typedef QStringView::size_type Alias for qsizetype. Provided for compatibility with the STL. */ /*! \fn QAnyStringView::QAnyStringView() Constructs a null string view. \sa isNull() */ /*! \fn QAnyStringView::QAnyStringView(std::nullptr_t) Constructs a null string view. \sa isNull() */ /*! \fn template QAnyStringView::QAnyStringView(const Char *str, qsizetype len) Constructs a string view on \a str with length \a len. The range \c{[str,len)} must remain valid for the lifetime of this string view object. Passing \nullptr as \a str is safe if \a len is 0, too, and results in a null string view. The behavior is undefined if \a len is negative or, when positive, if \a str is \nullptr. This constructor only participates in overload resolution if \c Char is a compatible character type. \sa isNull(), {Compatible Character Types} */ /*! \fn template QAnyStringView::QAnyStringView(const Char *first, const Char *last) Constructs a string view on \a first with length (\a last - \a first). The range \c{[first,last)} must remain valid for the lifetime of this string view object. Passing \c \nullptr as \a first is safe if \a last is \nullptr, too, and results in a null string view. The behavior is undefined if \a last precedes \a first, or \a first is \nullptr and \a last is not. This constructor only participates in overload resolution if \c Char is a compatible character type. \sa isNull(), {Compatible Character Types} */ /*! \fn template QAnyStringView::QAnyStringView(const Char *str) Constructs a string view on \a str. The length is determined by scanning for the first \c{Char(0)}. \a str must remain valid for the lifetime of this string view object. Passing \nullptr as \a str is safe and results in a null string view. This constructor only participates in overload resolution if \a str is not an array and if \c Char is a compatible character type. \sa isNull(), {Compatible Character Types} */ /*! \fn template QAnyStringView::QAnyStringView(const Char (&string)[N]) Constructs a string view on the character string literal \a string. The length is set to \c{N-1}, excluding the trailing \c{Char(0)}. If you need the full array, use the constructor from pointer and size instead: \snippet code/src_corelib_text_qanystringview.cpp 2 \a string must remain valid for the lifetime of this string view object. This constructor only participates in overload resolution if \a string is an actual array and \c Char is a compatible character type. \sa {Compatible Character Types} */ /*! \fn QAnyStringView::QAnyStringView(const QString &str) Constructs a string view on \a str. \c{str.data()} must remain valid for the lifetime of this string view object. The string view will be null if and only if \c{str.isNull()}. */ /*! \fn QAnyStringView::QAnyStringView(const QByteArray &str) Constructs a string view on \a str. The data in \a str is interpreted as UTF-8. \c{str.data()} must remain valid for the lifetime of this string view object. The string view will be null if and only if \c{str.isNull()}. */ /*! \fn template QAnyStringView::QAnyStringView(const StdBasicString &str) Constructs a string view on \a str. The length is taken from \c{str.size()}. \c{str.data()} must remain valid for the lifetime of this string view object. This constructor only participates in overload resolution if \c StdBasicString is an instantiation of \c std::basic_string with a compatible character type. The string view will be empty if and only if \c{str.empty()}. It is unspecified whether this constructor can result in a null string view (\c{str.data()} would have to return \nullptr for this). \sa isNull(), isEmpty(), {Compatible Character Types} */ /*! \fn QString QAnyStringView::toString() const Returns a deep copy of this string view's data as a QString. The return value will be a null QString if and only if this string view is null. */ /*! \fn const void *QStringView::data() const Returns a const pointer to the first character in the string. \note The character array represented by the return value is \e not null-terminated. \sa size_bytes() */ /*! \fn bool QAnyStringView::empty() const Returns whether this string view is empty - that is, whether \c{size() == 0}. This function is provided for STL compatibility. \sa isEmpty(), isNull(), size() */ /*! \fn bool QAnyStringView::isEmpty() const Returns whether this string view is empty - that is, whether \c{size() == 0}. This function is provided for compatibility with other Qt containers. \sa empty(), isNull(), size() */ /*! \fn bool QAnyStringView::isNull() const Returns whether this string view is null - that is, whether \c{data() == nullptr}. This functions is provided for compatibility with other Qt containers. \sa empty(), isEmpty(), size() */ /*! \fn qsizetype QAnyStringView::size() const Returns the size of this string view, in the encoding's code points. \sa empty(), isEmpty(), isNull(), size_bytes(), {Sizes and Sub-Strings} */ /*! \fn QAnyStringView::size_bytes() const Returns the size of this string view, but in bytes, not code-points. You can use this function together with data() for hashing or serialization. This function is provided for STL compatibility. \sa size(), data() */ /*! \fn int QStringView::length() const \obsolete Use size() instead, and port callers to qsizetype. Same as size(), except that it returns the result as an \c int. This function is provided for compatibility with other Qt containers. \warning QAnyStringView can represent strings with more than 2\sup{31} characters. Calling this function on a string view for which size() returns a value greater than \c{INT_MAX} constitutes undefined behavior. \sa size() */ /*! \fn QChar QAnyStringView::front() const Returns the first character in the string. This function is provided for STL compatibility. \warning Calling this function on an empty string view constitutes undefined behavior. \sa back(), {Sizes and Sub-Strings} */ /*! \fn QChar QAnyStringView::back() const Returns the last character in the string. This function is provided for STL compatibility. \warning Calling this function on an empty string view constitutes undefined behavior. \sa front(), {Sizes and Sub-Strings} */ /*! \fn QAnyStringView::compare(QAnyStringView lhs, QAnyStringView rhs, Qt::CaseSensitivity cs) Returns an integer that compares to zero as \a lhs compares to \a rhs. If \a cs is Qt::CaseSensitive (the default), the comparison is case sensitive; otherwise the comparison is case-insensitive. \sa operator==(), operator<(), operator>() */ /*! \fn template qToAnyStringViewIgnoringNull(const QStringLike &s); \since 6.0 \internal Convert \a s to a QAnyStringView ignoring \c{s.isNull()}. Returns a string-view that references \a{s}'s data, but is never null. This is a faster way to convert a QString or QByteArray to a QAnyStringView, if null QStrings or QByteArrays can legitimately be treated as empty ones. \sa QString::isNull(), QAnyStringView */ /*! \fn QAnyStringView::toWCharArray(wchar_t *array) const Transcribes this string into the given \a array. The caller is responsible for ensuring \a array is large enough to hold the \c wchar_t encoding of this string (allocating the array with space for size() elements is always sufficient). The array is encoded in UTF-16 on platforms where \c wchar_t is 2 bytes wide (e.g. Windows); otherwise (Unix systems), \c wchar_t is assumed to be 4 bytes wide and the data is written in UCS-4. \note This function writes no null terminator to the end of \a array. Returns the number of \c wchar_t entries written to \a array. \sa QString::toWCharArray() */