4 files changed, 44 insertions, 3 deletions
diff --git a/src/corelib/tools/qstring.cpp b/src/corelib/tools/qstring.cpp
index 8093a26f7d..e6b4cc4b4f 100644
--- a/src/corelib/tools/qstring.cpp
+++ b/src/corelib/tools/qstring.cpp
@@ -8506,7 +8506,7 @@ bool QString::isSimpleText() const
 */
 bool QString::isRightToLeft() const
 {
-    return QStringRef(this).isRightToLeft();
+    return QtPrivate::isRightToLeft(QStringView(*this));
 }
 
 /*! \fn QChar *QString::data()
@@ -10778,8 +10778,23 @@ int QStringRef::count(const QStringRef &str, Qt::CaseSensitivity cs) const
 */
 bool QStringRef::isRightToLeft() const
 {
-    const ushort *p = reinterpret_cast<const ushort*>(unicode());
-    const ushort * const end = p + size();
+    return QtPrivate::isRightToLeft(QStringView(unicode(), size()));
+}
+
+/*!
+    \since 5.11
+    \internal
+    \relates QStringView
+
+    Returns \c true if the string is read right to left.
+
+    \sa QString::isRightToLeft()
+*/
+bool QtPrivate::isRightToLeft(QStringView string)
+{
+    const ushort *p = reinterpret_cast<const ushort*>(string.data());
+    const ushort * const end = p + string.size();
+    int isolateLevel = 0;
     while (p < end) {
         uint ucs4 = *p;
         if (QChar::isHighSurrogate(ucs4) && p < end - 1) {
@@ -10791,10 +10806,23 @@ bool QStringRef::isRightToLeft() const
         }
         switch (QChar::direction(ucs4))
         {
+        case QChar::DirRLI:
+        case QChar::DirLRI:
+        case QChar::DirFSI:
+            ++isolateLevel;
+            break;
+        case QChar::DirPDI:
+            if (isolateLevel)
+                --isolateLevel;
+            break;
         case QChar::DirL:
+            if (isolateLevel)
+                break;
             return false;
         case QChar::DirR:
         case QChar::DirAL:
+            if (isolateLevel)
+                break;
             return true;
         default:
             break;
diff --git a/src/corelib/tools/qstringalgorithms.h b/src/corelib/tools/qstringalgorithms.h
index aaa702301e..6146e525d9 100644
--- a/src/corelib/tools/qstringalgorithms.h
+++ b/src/corelib/tools/qstringalgorithms.h
@@ -80,6 +80,7 @@ Q_REQUIRED_RESULT Q_CORE_EXPORT QByteArray convertToLatin1(QStringView str);
 Q_REQUIRED_RESULT Q_CORE_EXPORT QByteArray convertToUtf8(QStringView str);
 Q_REQUIRED_RESULT Q_CORE_EXPORT QByteArray convertToLocal8Bit(QStringView str);
 Q_REQUIRED_RESULT Q_CORE_EXPORT QVector<uint> convertToUcs4(QStringView str);
+Q_REQUIRED_RESULT Q_CORE_EXPORT bool isRightToLeft(QStringView string);
 
 } // namespace QtPRivate
 
diff --git a/src/corelib/tools/qstringview.cpp b/src/corelib/tools/qstringview.cpp
index 6321427a2d..f1abf13454 100644
--- a/src/corelib/tools/qstringview.cpp
+++ b/src/corelib/tools/qstringview.cpp
@@ -772,4 +772,13 @@ QT_BEGIN_NAMESPACE
     \sa QString::isNull(), QStringRef::isNull(), QStringView
 */
 
+/*!
+    \fn bool QStringView::isRightToLeft();
+    \since 5.11
+
+    Returns \c true if the string is read right to left.
+
+    \sa QString::isRightToLeft()
+*/
+
 QT_END_NAMESPACE
diff --git a/src/corelib/tools/qstringview.h b/src/corelib/tools/qstringview.h
index ef442e5b65..480021a165 100644
--- a/src/corelib/tools/qstringview.h
+++ b/src/corelib/tools/qstringview.h
@@ -266,6 +266,9 @@ public:
     Q_REQUIRED_RESULT bool endsWith(QChar c, Qt::CaseSensitivity cs) const Q_DECL_NOTHROW
     { return QtPrivate::endsWith(*this, QStringView(&c, 1), cs); }
 
+    Q_REQUIRED_RESULT bool isRightToLeft() const Q_DECL_NOTHROW
+    { return QtPrivate::isRightToLeft(*this); }
+
     //
     // STL compatibility API:
     //