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| |
| #include "qstringbuilder.h" |
| #include <private/qutfcodec_p.h> |
| |
| QT_BEGIN_NAMESPACE |
| |
| /*! |
| \class QStringBuilder |
| \inmodule QtCore |
| \internal |
| \reentrant |
| \since 4.6 |
| |
| \brief The QStringBuilder class is a template class that provides a facility to build up QStrings and QByteArrays from smaller chunks. |
| |
| \ingroup tools |
| \ingroup shared |
| \ingroup string-processing |
| |
| |
| To build a QString by multiple concatenations, QString::operator+() |
| is typically used. This causes \e{n - 1} allocations when building |
| a string from \e{n} chunks. The same is true for QByteArray. |
| |
| QStringBuilder uses expression templates to collect the individual |
| chunks, compute the total size, allocate the required amount of |
| memory for the final string object, and copy the chunks into the |
| allocated memory. |
| |
| The QStringBuilder class is not to be used explicitly in user |
| code. Instances of the class are created as return values of the |
| operator%() function, acting on objects of the following types: |
| |
| For building QStrings: |
| |
| \list |
| \li QString, QStringRef, (since 5.10:) QStringView |
| \li QChar, QCharRef, QLatin1Char, (since 5.10:) \c char16_t, |
| \li QLatin1String, |
| \li (since 5.10:) \c{const char16_t[]} (\c{u"foo"}), |
| \li QByteArray, \c char, \c{const char[]}. |
| \endlist |
| |
| The types in the last list point are only available when |
| \c QT_NO_CAST_FROM_ASCII is not defined. |
| |
| For building QByteArrays: |
| |
| \list |
| \li QByteArray, \c char, \c{const char[]}. |
| \endlist |
| |
| Concatenating strings with operator%() generally yields better |
| performance than using \c QString::operator+() on the same chunks |
| if there are three or more of them, and performs equally well in other |
| cases. |
| |
| \sa QLatin1String, QString |
| */ |
| |
| /*! \fn template <typename A, typename B> QStringBuilder<A, B>::QStringBuilder(const A &a, const B &b) |
| Constructs a QStringBuilder from \a a and \a b. |
| */ |
| |
| /* \fn template <typename A, typename B> QStringBuilder<A, B>::operator%(const A &a, const B &b) |
| |
| Returns a \c QStringBuilder object that is converted to a QString object |
| when assigned to a variable of QString type or passed to a function that |
| takes a QString parameter. |
| |
| This function is usable with arguments of type \c QString, |
| \c QLatin1String, \c QStringRef, |
| \c QChar, \c QCharRef, \c QLatin1Char, and \c char. |
| */ |
| |
| /* \fn template <typename A, typename B> QByteArray QStringBuilder<A, B>::toLatin1() const |
| Returns a Latin-1 representation of the string as a QByteArray. The |
| returned byte array is undefined if the string contains non-Latin1 |
| characters. |
| */ |
| /* \fn template <typename A, typename B> QByteArray QStringBuilder<A, B>::toUtf8() const |
| Returns a UTF-8 representation of the string as a QByteArray. |
| */ |
| |
| |
| /*! |
| \internal |
| */ |
| void QAbstractConcatenable::convertFromAscii(const char *a, int len, QChar *&out) noexcept |
| { |
| if (Q_UNLIKELY(len == -1)) { |
| if (!a) |
| return; |
| len = int(strlen(a)); |
| } |
| out = QUtf8::convertToUnicode(out, a, len); |
| } |
| |
| QT_END_NAMESPACE |