From 4682af483fd7f6e06e28c237f5029733927652fd Mon Sep 17 00:00:00 2001
From: Ievgenii Meshcheriakov <ievgenii.meshcheriakov@qt.io>
Date: Thu, 7 Oct 2021 17:28:32 +0200
Subject: [PATCH] QString: Use QStringIterator in QtPrivate::isRightToLeft()

This simplifies the code. While at it, also expand default case
so changes in the QChar::Direction enum don't go unnoticed.

Change-Id: Id52140b0aaf7fd259c4b8079462811603eb3ff93
Reviewed-by: Edward Welbourne <edward.welbourne@qt.io>
Reviewed-by: Giuseppe D'Angelo <giuseppe.dangelo@kdab.com>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
---
 src/corelib/text/qstring.cpp | 36 +++++++++++++++++++++---------------
 1 file changed, 21 insertions(+), 15 deletions(-)

diff --git a/src/corelib/text/qstring.cpp b/src/corelib/text/qstring.cpp
index ec813ee750..437fde6875 100644
--- a/src/corelib/text/qstring.cpp
+++ b/src/corelib/text/qstring.cpp
@@ -9974,20 +9974,12 @@ QDataStream &operator>>(QDataStream &in, QString &str)
 */
 bool QtPrivate::isRightToLeft(QStringView string) noexcept
 {
-    const char16_t *p = string.utf16();
-    const char16_t * const end = p + string.size();
     int isolateLevel = 0;
-    while (p < end) {
-        uint ucs4 = *p;
-        if (QChar::isHighSurrogate(ucs4) && p < end - 1) {
-            char16_t low = p[1];
-            if (QChar::isLowSurrogate(low)) {
-                ucs4 = QChar::surrogateToUcs4(ucs4, low);
-                ++p;
-            }
-        }
-        switch (QChar::direction(ucs4))
-        {
+
+    for (QStringIterator i(string); i.hasNext();) {
+        const char32_t c = i.next();
+
+        switch (QChar::direction(c)) {
         case QChar::DirRLI:
         case QChar::DirLRI:
         case QChar::DirFSI:
@@ -10006,10 +9998,24 @@ bool QtPrivate::isRightToLeft(QStringView string) noexcept
             if (isolateLevel)
                 break;
             return true;
-        default:
+        case QChar::DirEN:
+        case QChar::DirES:
+        case QChar::DirET:
+        case QChar::DirAN:
+        case QChar::DirCS:
+        case QChar::DirB:
+        case QChar::DirS:
+        case QChar::DirWS:
+        case QChar::DirON:
+        case QChar::DirLRE:
+        case QChar::DirLRO:
+        case QChar::DirRLE:
+        case QChar::DirRLO:
+        case QChar::DirPDF:
+        case QChar::DirNSM:
+        case QChar::DirBN:
             break;
         }
-        ++p;
     }
     return false;
 }