include/QtCore/qstringbuilder.h

0001 // Copyright (C) 2020 The Qt Company Ltd.
0002 // SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
0003 // Qt-Security score:critical reason:data-parser
0004
0005 #include <QtCore/qstring.h>
0006
0007 #ifndef QSTRINGBUILDER_H
0008 #define QSTRINGBUILDER_H
0009
0010 #if 0
0011 // syncqt can not handle the templates in this file, and it doesn't need to
0012 // process them anyway because they are internal.
0013 #pragma qt_class(QStringBuilder)
0014 #pragma qt_sync_stop_processing
0015 #endif
0016
0017 #include <QtCore/qbytearray.h>
0018
0019 #include <string.h>
0020
0021 QT_BEGIN_NAMESPACE
0022
0023
0024 struct Q_CORE_EXPORT QAbstractConcatenable
0025 {
0026 protected:
0027     static void convertFromUtf8(QByteArrayView in, QChar *&out) noexcept;
0028     static inline void convertFromAscii(char a, QChar *&out) noexcept
0029     {
0030         *out++ = QLatin1Char(a);
0031     }
0032     static void appendLatin1To(QLatin1StringView in, QChar *out) noexcept;
0033 };
0034
0035 template <typename T> struct QConcatenable;
0036
0037 template <typename T>
0038 using QConcatenableEx = QConcatenable<q20::remove_cvref_t<T>>;
0039
0040 namespace QtStringBuilder {
0041     template <typename A, typename B> struct ConvertToTypeHelper
0042     { typedef A ConvertTo; };
0043     template <typename T> struct ConvertToTypeHelper<T, QString>
0044     { typedef QString ConvertTo; };
0045
0046     template <typename T> using HasIsNull = decltype(std::declval<const T &>().isNull());
0047     template <typename T> bool isNull(const T &t)
0048     {
0049         if constexpr (qxp::is_detected_v<HasIsNull, T>)
0050             return t.isNull();
0051         else
0052             return false;
0053     }
0054 }
0055
0056 template<typename Builder, typename T>
0057 struct QStringBuilderCommon
0058 {
0059     T toUpper() const { return resolved().toUpper(); }
0060     T toLower() const { return resolved().toLower(); }
0061
0062 protected:
0063     T resolved() const { return *static_cast<const Builder*>(this); }
0064 };
0065
0066 template<typename Builder, typename T>
0067 struct QStringBuilderBase : public QStringBuilderCommon<Builder, T>
0068 {
0069 };
0070
0071 template<typename Builder>
0072 struct QStringBuilderBase<Builder, QString> : public QStringBuilderCommon<Builder, QString>
0073 {
0074     QByteArray toLatin1() const { return this->resolved().toLatin1(); }
0075     QByteArray toUtf8() const { return this->resolved().toUtf8(); }
0076     QByteArray toLocal8Bit() const { return this->resolved().toLocal8Bit(); }
0077 };
0078
0079 template <typename A, typename B>
0080 class QStringBuilder : public QStringBuilderBase<QStringBuilder<A, B>,
0081                                                  typename QtStringBuilder::ConvertToTypeHelper<
0082                                                          typename QConcatenableEx<A>::ConvertTo,
0083                                                          typename QConcatenableEx<B>::ConvertTo
0084                                                          >::ConvertTo
0085                                                 >
0086 {
0087 public:
0088     QStringBuilder(A &&a_, B &&b_) : a(std::forward<A>(a_)), b(std::forward<B>(b_)) {}
0089
0090     QStringBuilder(QStringBuilder &&) = default;
0091     QStringBuilder(const QStringBuilder &) = default;
0092     ~QStringBuilder() = default;
0093
0094 private:
0095     friend class QByteArray;
0096     friend class QString;
0097     template <typename T> T convertTo() const
0098     {
0099         if (isNull()) {
0100             // appending two null strings must give back a null string,
0101             // so we're special casing this one out, QTBUG-114206
0102             return T();
0103         }
0104         return convertToImpl<T>(Concatenable::size(*this));
0105     }
0106     template <typename T> T convertToImpl(const qsizetype len) const
0107     {
0108         T s(len, Qt::Uninitialized);
0109
0110         // Using data_ptr() here (private API) so we can bypass the
0111         // isDetached() and the replacement of a null pointer with _empty in
0112         // both QString and QByteArray's data() and constData(). The result is
0113         // the same if len != 0.
0114         auto d = reinterpret_cast<typename T::iterator>(s.data_ptr().data());
0115         const auto start = d;
0116         Concatenable::appendTo(*this, d);
0117
0118         if constexpr (Concatenable::ExactSize) {
0119             Q_UNUSED(start)
0120         } else {
0121             if (len != d - start) {
0122                 // this resize is necessary since we allocate a bit too much
0123                 // when dealing with variable sized 8-bit encodings
0124                 s.resize(d - start);
0125             }
0126         }
0127         return s;
0128     }
0129
0130     typedef QConcatenable<QStringBuilder<A, B> > Concatenable;
0131 public:
0132     typedef typename Concatenable::ConvertTo ConvertTo;
0133     operator ConvertTo() const { return convertTo<ConvertTo>(); }
0134
0135     qsizetype size() const { return Concatenable::size(*this); }
0136
0137     bool isNull() const
0138     {
0139         return QtStringBuilder::isNull(a) && QtStringBuilder::isNull(b);
0140     }
0141
0142     A a;
0143     B b;
0144
0145 private:
0146     QStringBuilder &operator=(QStringBuilder &&) = delete;
0147     QStringBuilder &operator=(const QStringBuilder &) = delete;
0148 };
0149
0150 template <> struct QConcatenable<char> : private QAbstractConcatenable
0151 {
0152     typedef char type;
0153     typedef QByteArray ConvertTo;
0154     enum { ExactSize = true };
0155     static qsizetype size(const char) { return 1; }
0156 #ifndef QT_NO_CAST_FROM_ASCII
0157     QT_ASCII_CAST_WARN static inline void appendTo(const char c, QChar *&out)
0158     {
0159         QAbstractConcatenable::convertFromAscii(c, out);
0160     }
0161 #endif
0162     static inline void appendTo(const char c, char *&out)
0163     { *out++ = c; }
0164 };
0165
0166 template <> struct QConcatenable<QByteArrayView> : private QAbstractConcatenable
0167 {
0168     typedef QByteArrayView type;
0169     typedef QByteArray ConvertTo;
0170     enum { ExactSize = true };
0171     static qsizetype size(QByteArrayView bav) { return bav.size(); }
0172 #ifndef QT_NO_CAST_FROM_ASCII
0173     QT_ASCII_CAST_WARN static inline void appendTo(QByteArrayView bav, QChar *&out)
0174     {
0175         QAbstractConcatenable::convertFromUtf8(bav, out);
0176     }
0177 #endif
0178     static inline void appendTo(QByteArrayView bav, char *&out)
0179     {
0180         qsizetype n = bav.size();
0181         if (n)
0182             memcpy(out, bav.data(), n);
0183         out += n;
0184     }
0185 };
0186
0187 template <> struct QConcatenable<char16_t> : private QAbstractConcatenable
0188 {
0189     typedef char16_t type;
0190     typedef QString ConvertTo;
0191     enum { ExactSize = true };
0192     static constexpr qsizetype size(char16_t) { return 1; }
0193     static inline void appendTo(char16_t c, QChar *&out)
0194     { *out++ = c; }
0195 };
0196
0197 template <> struct QConcatenable<QLatin1Char>
0198 {
0199     typedef QLatin1Char type;
0200     typedef QString ConvertTo;
0201     enum { ExactSize = true };
0202     static qsizetype size(const QLatin1Char) { return 1; }
0203     static inline void appendTo(const QLatin1Char c, QChar *&out)
0204     { *out++ = c; }
0205     static inline void appendTo(const QLatin1Char c, char *&out)
0206     { *out++ = c.toLatin1(); }
0207 };
0208
0209 template <> struct QConcatenable<QChar> : private QAbstractConcatenable
0210 {
0211     typedef QChar type;
0212     typedef QString ConvertTo;
0213     enum { ExactSize = true };
0214     static qsizetype size(const QChar) { return 1; }
0215     static inline void appendTo(const QChar c, QChar *&out)
0216     { *out++ = c; }
0217 };
0218
0219 template <> struct QConcatenable<QChar::SpecialCharacter> : private QAbstractConcatenable
0220 {
0221     typedef QChar::SpecialCharacter type;
0222     typedef QString ConvertTo;
0223     enum { ExactSize = true };
0224     static qsizetype size(const QChar::SpecialCharacter) { return 1; }
0225     static inline void appendTo(const QChar::SpecialCharacter c, QChar *&out)
0226     { *out++ = c; }
0227 };
0228
0229 template <> struct QConcatenable<QLatin1StringView> : private QAbstractConcatenable
0230 {
0231     typedef QLatin1StringView type;
0232     typedef QString ConvertTo;
0233     enum { ExactSize = true };
0234     static qsizetype size(const QLatin1StringView a) { return a.size(); }
0235     static inline void appendTo(const QLatin1StringView a, QChar *&out)
0236     {
0237         appendLatin1To(a, out);
0238         out += a.size();
0239     }
0240     static inline void appendTo(const QLatin1StringView a, char *&out)
0241     {
0242         if (const char *data = a.data()) {
0243             memcpy(out, data, a.size());
0244             out += a.size();
0245         }
0246     }
0247 };
0248
0249 template <> struct QConcatenable<QString> : private QAbstractConcatenable
0250 {
0251     typedef QString type;
0252     typedef QString ConvertTo;
0253     enum { ExactSize = true };
0254     static qsizetype size(const QString &a) { return a.size(); }
0255     static inline void appendTo(const QString &a, QChar *&out)
0256     {
0257         const qsizetype n = a.size();
0258         if (n)
0259             memcpy(out, a.data(), sizeof(QChar) * n);
0260         out += n;
0261     }
0262 };
0263
0264 template <> struct QConcatenable<QStringView> : private QAbstractConcatenable
0265 {
0266     typedef QStringView type;
0267     typedef QString ConvertTo;
0268     enum { ExactSize = true };
0269     static qsizetype size(QStringView a) { return a.size(); }
0270     static inline void appendTo(QStringView a, QChar *&out)
0271     {
0272         const auto n = a.size();
0273         if (n)
0274             memcpy(out, a.data(), sizeof(QChar) * n);
0275         out += n;
0276     }
0277 };
0278
0279 template <qsizetype N> struct QConcatenable<const char[N]> : private QAbstractConcatenable
0280 {
0281     typedef const char type[N];
0282     typedef QByteArray ConvertTo;
0283     enum { ExactSize = false };
0284     static qsizetype size(const char[N]) { return N - 1; }
0285 #ifndef QT_NO_CAST_FROM_ASCII
0286     QT_ASCII_CAST_WARN static inline void appendTo(const char a[N], QChar *&out)
0287     {
0288         QAbstractConcatenable::convertFromUtf8(QByteArrayView(a, N - 1), out);
0289     }
0290 #endif
0291     static inline void appendTo(const char a[N], char *&out)
0292     {
0293         while (*a)
0294             *out++ = *a++;
0295     }
0296 };
0297
0298 template <qsizetype N> struct QConcatenable<char[N]> : QConcatenable<const char[N]>
0299 {
0300     typedef char type[N];
0301 };
0302
0303 template <> struct QConcatenable<const char *> : private QAbstractConcatenable
0304 {
0305     typedef const char *type;
0306     typedef QByteArray ConvertTo;
0307     enum { ExactSize = false };
0308     static qsizetype size(const char *a) { return qstrlen(a); }
0309 #ifndef QT_NO_CAST_FROM_ASCII
0310     QT_ASCII_CAST_WARN static inline void appendTo(const char *a, QChar *&out)
0311     { QAbstractConcatenable::convertFromUtf8(QByteArrayView(a), out); }
0312 #endif
0313     static inline void appendTo(const char *a, char *&out)
0314     {
0315         if (!a)
0316             return;
0317         while (*a)
0318             *out++ = *a++;
0319     }
0320 };
0321
0322 template <> struct QConcatenable<char *> : QConcatenable<const char*>
0323 {
0324     typedef char *type;
0325 };
0326
0327 template <qsizetype N> struct QConcatenable<const char16_t[N]> : private QAbstractConcatenable
0328 {
0329     using type = const char16_t[N];
0330     using ConvertTo = QString;
0331     enum { ExactSize = true };
0332     static qsizetype size(const char16_t[N]) { return N - 1; }
0333     static void appendTo(const char16_t a[N], QChar *&out)
0334     {
0335         memcpy(static_cast<void *>(out), a, (N - 1) * sizeof(char16_t));
0336         out += N - 1;
0337     }
0338 };
0339
0340 template <qsizetype N> struct QConcatenable<char16_t[N]> : QConcatenable<const char16_t[N]>
0341 {
0342     using type = char16_t[N];
0343 };
0344
0345 template <> struct QConcatenable<const char16_t *> : private QAbstractConcatenable
0346 {
0347     using type = const char16_t *;
0348     using ConvertTo = QString;
0349     enum { ExactSize = true };
0350     static qsizetype size(const char16_t *a) { return QStringView(a).size(); }
0351     QT_ASCII_CAST_WARN static inline void appendTo(const char16_t *a, QChar *&out)
0352     {
0353         if (!a)
0354             return;
0355         while (*a)
0356             *out++ = *a++;
0357     }
0358 };
0359
0360 template <> struct QConcatenable<char16_t *> : QConcatenable<const char16_t*>
0361 {
0362     typedef char16_t *type;
0363 };
0364
0365 template <> struct QConcatenable<QByteArray> : private QAbstractConcatenable
0366 {
0367     typedef QByteArray type;
0368     typedef QByteArray ConvertTo;
0369     enum { ExactSize = false };
0370     static qsizetype size(const QByteArray &ba) { return ba.size(); }
0371 #ifndef QT_NO_CAST_FROM_ASCII
0372     QT_ASCII_CAST_WARN static inline void appendTo(const QByteArray &ba, QChar *&out)
0373     {
0374         QAbstractConcatenable::convertFromUtf8(ba, out);
0375     }
0376 #endif
0377     static inline void appendTo(const QByteArray &ba, char *&out)
0378     {
0379         const qsizetype n = ba.size();
0380         if (n)
0381             memcpy(out, ba.begin(), n);
0382         out += n;
0383     }
0384 };
0385
0386
0387 template <typename A, typename B>
0388 struct QConcatenable< QStringBuilder<A, B> >
0389 {
0390     typedef QStringBuilder<A, B> type;
0391     using ConvertTo = typename QtStringBuilder::ConvertToTypeHelper<
0392                 typename QConcatenableEx<A>::ConvertTo,
0393                 typename QConcatenableEx<B>::ConvertTo
0394             >::ConvertTo;
0395     enum { ExactSize = QConcatenableEx<A>::ExactSize && QConcatenableEx<B>::ExactSize };
0396     static qsizetype size(const type &p)
0397     {
0398         return QConcatenableEx<A>::size(p.a) + QConcatenableEx<B>::size(p.b);
0399     }
0400     template<typename T> static inline void appendTo(const type &p, T *&out)
0401     {
0402         QConcatenableEx<A>::appendTo(p.a, out);
0403         QConcatenableEx<B>::appendTo(p.b, out);
0404     }
0405 };
0406
0407 template <typename A, typename B,
0408          typename = std::void_t<typename QConcatenableEx<A>::type, typename QConcatenableEx<B>::type>>
0409 auto operator%(A &&a, B &&b)
0410 {
0411     return QStringBuilder<A, B>(std::forward<A>(a), std::forward<B>(b));
0412 }
0413
0414 // QT_USE_FAST_OPERATOR_PLUS was introduced in 4.7, QT_USE_QSTRINGBUILDER is to be used from 4.8 onwards
0415 // QT_USE_FAST_OPERATOR_PLUS does not remove the normal operator+ for QByteArray
0416 #if defined(QT_USE_FAST_OPERATOR_PLUS) || defined(QT_USE_QSTRINGBUILDER)
0417 template <typename A, typename B,
0418          typename = std::void_t<typename QConcatenableEx<A>::type, typename QConcatenableEx<B>::type>>
0419 auto operator+(A &&a, B &&b)
0420 {
0421     return std::forward<A>(a) % std::forward<B>(b);
0422 }
0423 #endif
0424
0425 namespace QtStringBuilder {
0426 template <typename A, typename B>
0427 QByteArray &appendToByteArray(QByteArray &a, const QStringBuilder<A, B> &b, char)
0428 {
0429     // append 8-bit data to a byte array
0430     qsizetype len = a.size() + QConcatenable< QStringBuilder<A, B> >::size(b);
0431     a.detach(); // a detach() in a.data() could reset a.capacity() to a.size()
0432     if (len > a.data_ptr().freeSpaceAtEnd()) // capacity() was broken when prepend()-optimization landed
0433         a.reserve(qMax(len, 2 * a.capacity()));
0434     char *it = a.data() + a.size();
0435     QConcatenable< QStringBuilder<A, B> >::appendTo(b, it);
0436     a.resize(len); //we need to resize after the appendTo for the case str+=foo+str
0437     return a;
0438 }
0439
0440 #ifndef QT_NO_CAST_TO_ASCII
0441 template <typename A, typename B>
0442 QByteArray &appendToByteArray(QByteArray &a, const QStringBuilder<A, B> &b, QChar)
0443 {
0444     return a += QString(b).toUtf8();
0445 }
0446 #endif
0447 }
0448
0449 template <typename A, typename B>
0450 QByteArray &operator+=(QByteArray &a, const QStringBuilder<A, B> &b)
0451 {
0452     return QtStringBuilder::appendToByteArray(a, b,
0453                                               typename QConcatenable< QStringBuilder<A, B> >::ConvertTo::value_type());
0454 }
0455
0456 template <typename A, typename B>
0457 QString &operator+=(QString &a, const QStringBuilder<A, B> &b)
0458 {
0459     qsizetype len = a.size() + QConcatenable< QStringBuilder<A, B> >::size(b);
0460     a.detach(); // a detach() in a.data() could reset a.capacity() to a.size()
0461     if (len > a.data_ptr().freeSpaceAtEnd()) // capacity() was broken when prepend()-optimization landed
0462         a.reserve(qMax(len, 2 * a.capacity()));
0463     QChar *it = a.data() + a.size();
0464     QConcatenable< QStringBuilder<A, B> >::appendTo(b, it);
0465     // we need to resize after the appendTo for the case str+=foo+str
0466     a.resize(it - a.constData()); //may be smaller than len if there was conversion from utf8
0467     return a;
0468 }
0469
0470 QT_END_NAMESPACE
0471
0472 #endif // QSTRINGBUILDER_H