Change QStringBuilder to use UTF-8 too

This commit completes the previous commit so that both QString and
QStringBuilder now operate on UTF-8 input.

A small fix was required in QStringBuilder: an if clause isn't enough
to separate the two append versions. Since there are no QString
functions that append to char*, if we're converting to a QByteArray,
we need to go through a QString first in a separate function.

Change-Id: Ic503340c5d0c32d420c90c91cc2e0fc1ae9230f3
Reviewed-by: Lars Knoll <lars.knoll@nokia.com>

2 files changed, 34 insertions, 9 deletions

diff --git a/src/corelib/tools/qstringbuilder.cpp b/src/corelib/tools/qstringbuilder.cpp
index a044cca3c9..2fe556096b 100644
--- a/src/corelib/tools/qstringbuilder.cpp
+++ b/src/corelib/tools/qstringbuilder.cpp
@@ -108,12 +108,24 @@ void QAbstractConcatenable::convertFromAscii(const char *a, int len, QChar *&out
     if (len == -1) {
         if (!a)
             return;
-        while (*a)
+        while (*a && uchar(*a) < 0x80U)
             *out++ = QLatin1Char(*a++);
+        if (!*a)
+            return;
     } else {
-        for (int i = 0; i < len; ++i)
+        int i;
+        for (i = 0; i < len && uchar(a[i]) < 0x80U; ++i)
             *out++ = QLatin1Char(a[i]);
+        if (i == len)
+            return;
+        a += i;
+        len -= i;
     }
+
+    // we need to complement with UTF-8 appending
+    QString tmp = QString::fromUtf8(a, len);
+    memcpy(out, reinterpret_cast<const char *>(tmp.constData()), sizeof(QChar) * tmp.size());
+    out += tmp.size();
 }
 
 QT_END_NAMESPACE
diff --git a/src/corelib/tools/qstringbuilder.h b/src/corelib/tools/qstringbuilder.h
index 9b1cd1ee7e..6b258eb09a 100644
--- a/src/corelib/tools/qstringbuilder.h
+++ b/src/corelib/tools/qstringbuilder.h
@@ -381,15 +381,11 @@ operator+(const A &a, const B &b)
 }
 #endif
 
+namespace QtStringBuilder {
 template <typename A, typename B>
-QByteArray &operator+=(QByteArray &a, const QStringBuilder<A, B> &b)
+QByteArray &appendToByteArray(QByteArray &a, const QStringBuilder<A, B> &b, char)
 {
-#ifndef QT_NO_CAST_TO_ASCII
-    if (sizeof(typename QConcatenable< QStringBuilder<A, B> >::ConvertTo::value_type) == sizeof(QChar)) {
-        //it is not save to optimize as in utf8 it is not possible to compute the size
-        return a += QString(b);
-    }
-#endif
+    // append 8-bit data to a byte array
     int len = a.size() + QConcatenable< QStringBuilder<A, B> >::size(b);
     a.reserve(len);
     char *it = a.data() + a.size();
@@ -398,6 +394,23 @@ QByteArray &operator+=(QByteArray &a, const QStringBuilder<A, B> &b)
     return a;
 }
 
+#ifndef QT_NO_CAST_TO_ASCII
+template <typename A, typename B>
+QByteArray &appendToByteArray(QByteArray &a, const QStringBuilder<A, B> &b, QChar)
+{
+    // append UTF-16 data to the byte array
+    return a += QString(b);
+}
+#endif
+}
+
+template <typename A, typename B>
+QByteArray &operator+=(QByteArray &a, const QStringBuilder<A, B> &b)
+{
+    return QtStringBuilder::appendToByteArray(a, b,
+                                              typename QConcatenable< QStringBuilder<A, B> >::ConvertTo::value_type());
+}
+
 template <typename A, typename B>
 QString &operator+=(QString &a, const QStringBuilder<A, B> &b)
 {