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// Copyright (C) 2016 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
#include "qstringbuilder.h"
#include <private/qstringconverter_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, (since 5.10:) QStringView
\li QChar, QLatin1Char, (since 5.10:) \c char16_t,
\li QLatin1StringView,
\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.
\note Defining \c QT_USE_QSTRINGBUILDER at build time (this is the
default when building Qt libraries and tools), will make using \c {'+'}
when concatenating strings work the same way as \c operator%().
\sa QLatin1StringView, QString
*/
/*!
\internal
\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.
*/
/*!
\internal
\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 any of the following types:
\list
\li \c QAnyStringView,
\li \c QString, \c QStringView
\li \c QByteArray, \c QByteArrayView, \c QLatin1StringView
\li \c QChar, \c QLatin1Char, \c char, (since 5.10:) \c char16_t
\li (since 5.10:) \c{const char16_t[]} (\c{u"foo"}),
\endlist
*/
/*!
\internal
\fn template <typename A, typename B> QByteArray QStringBuilder<A, B>::toLatin1() const
Returns a Latin-1 representation of the string as a QByteArray. It
is undefined behavior if the string contains non-Latin1 characters.
*/
/*!
\internal
\fn template <typename A, typename B> QByteArray QStringBuilder<A, B>::toUtf8() const
Returns a UTF-8 representation of the string as a QByteArray.
*/
/*!
\internal
Converts the UTF-8 string viewed by \a in to UTF-16 and writes the result
to the buffer starting at \a out.
*/
void QAbstractConcatenable::convertFromUtf8(QByteArrayView in, QChar *&out) noexcept
{
out = QUtf8::convertToUnicode(out, in);
}
QT_END_NAMESPACE
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