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39
40#include "qstringbuilder.h"
41#include <private/qutfcodec_p.h>
42
43QT_BEGIN_NAMESPACE
44
45/*!
46 \class QStringBuilder
47 \inmodule QtCore
48 \internal
49 \reentrant
50 \since 4.6
51
52 \brief The QStringBuilder class is a template class that provides a facility to build up QStrings and QByteArrays from smaller chunks.
53
54 \ingroup tools
55 \ingroup shared
56 \ingroup string-processing
57
58
59 To build a QString by multiple concatenations, QString::operator+()
60 is typically used. This causes \e{n - 1} allocations when building
61 a string from \e{n} chunks. The same is true for QByteArray.
62
63 QStringBuilder uses expression templates to collect the individual
64 chunks, compute the total size, allocate the required amount of
65 memory for the final string object, and copy the chunks into the
66 allocated memory.
67
68 The QStringBuilder class is not to be used explicitly in user
69 code. Instances of the class are created as return values of the
70 operator%() function, acting on objects of the following types:
71
72 For building QStrings:
73
74 \list
75 \li QString, QStringRef, (since 5.10:) QStringView
76 \li QChar, QCharRef, QLatin1Char, (since 5.10:) \c char16_t,
77 \li QLatin1String,
78 \li (since 5.10:) \c{const char16_t[]} (\c{u"foo"}),
79 \li QByteArray, \c char, \c{const char[]}.
80 \endlist
81
82 The types in the last list point are only available when
83 \c QT_NO_CAST_FROM_ASCII is not defined.
84
85 For building QByteArrays:
86
87 \list
88 \li QByteArray, \c char, \c{const char[]}.
89 \endlist
90
91 Concatenating strings with operator%() generally yields better
92 performance than using \c QString::operator+() on the same chunks
93 if there are three or more of them, and performs equally well in other
94 cases.
95
96 \sa QLatin1String, QString
97*/
98
99/*! \fn template <typename A, typename B> QStringBuilder<A, B>::QStringBuilder(const A &a, const B &b)
100 Constructs a QStringBuilder from \a a and \a b.
101 */
102
103/* \fn template <typename A, typename B> QStringBuilder<A, B>::operator%(const A &a, const B &b)
104
105 Returns a \c QStringBuilder object that is converted to a QString object
106 when assigned to a variable of QString type or passed to a function that
107 takes a QString parameter.
108
109 This function is usable with arguments of type \c QString,
110 \c QLatin1String, \c QStringRef,
111 \c QChar, \c QCharRef, \c QLatin1Char, and \c char.
112*/
113
114/* \fn template <typename A, typename B> QByteArray QStringBuilder<A, B>::toLatin1() const
115 Returns a Latin-1 representation of the string as a QByteArray. The
116 returned byte array is undefined if the string contains non-Latin1
117 characters.
118 */
119/* \fn template <typename A, typename B> QByteArray QStringBuilder<A, B>::toUtf8() const
120 Returns a UTF-8 representation of the string as a QByteArray.
121 */
122
123
124/*!
125 \internal
126 */
127void QAbstractConcatenable::convertFromAscii(const char *a, int len, QChar *&out) noexcept
128{
129 if (Q_UNLIKELY(len == -1)) {
130 if (!a)
131 return;
132 len = int(strlen(s: a));
133 }
134 out = QUtf8::convertToUnicode(out, a, len);
135}
136
137QT_END_NAMESPACE
138

source code of qtbase/src/corelib/text/qstringbuilder.cpp