From 0ed8db78007be243ebb95c3aeafad64fa136630b Mon Sep 17 00:00:00 2001
From: Anton Kudryavtsev <anton.kudryavtsev@vk.team>
Date: Fri, 15 Sep 2023 12:39:34 +0300
Subject: [PATCH] QString::toHtmlEscaped: avoid unconditional copy

Let's find replaceable chars and then do copy

Change-Id: I2d365626218b0daf2023144dee7e901e8e99adc6
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
Reviewed-by: Edward Welbourne <edward.welbourne@qt.io>
---
 src/corelib/text/qstring.cpp | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/src/corelib/text/qstring.cpp b/src/corelib/text/qstring.cpp
index 68d0cb3e6f..81891e3cdb 100644
--- a/src/corelib/text/qstring.cpp
+++ b/src/corelib/text/qstring.cpp
@@ -9926,10 +9926,14 @@ qsizetype QtPrivate::count(QStringView haystack, const QRegularExpression &re)
 */
 QString QString::toHtmlEscaped() const
 {
+    const auto pos = std::u16string_view(*this).find_first_of(u"<>&\"");
+    if (pos == std::u16string_view::npos)
+        return *this;
     QString rich;
     const qsizetype len = size();
     rich.reserve(qsizetype(len * 1.1));
-    for (QChar ch : *this) {
+    rich += qToStringViewIgnoringNull(*this).first(pos);
+    for (auto ch : qToStringViewIgnoringNull(*this).sliced(pos)) {
         if (ch == u'<')
             rich += "&lt;"_L1;
         else if (ch == u'>')