Widgets: use QStringRef to optimize memory allocation

Replace substring functions that return QString with
corresponding functions that return QStringRef where
it's possible.

Create QString from QStringRef only where necessary.

Change-Id: Id1c39093199519f2794b11560c2c0ded2d52b928
Reviewed-by: Marc Mutz <marc.mutz@kdab.com>

4 files changed, 5 insertions, 5 deletions

diff --git a/src/widgets/widgets/qcalendarwidget.cpp b/src/widgets/widgets/qcalendarwidget.cpp
index 66e4a89fe9..caeabb660b 100644
--- a/src/widgets/widgets/qcalendarwidget.cpp
+++ b/src/widgets/widgets/qcalendarwidget.cpp
@@ -554,7 +554,7 @@ void QCalendarDateValidator::setFormat(const QString &format)
     bool quoting = false;
     QString separator;
     while (pos < format.size()) {
-        QString mid = format.mid(pos);
+        const QStringRef mid = format.midRef(pos);
         int offset = 1;
 
         if (mid.startsWith(quote)) {
diff --git a/src/widgets/widgets/qlineedit_p.cpp b/src/widgets/widgets/qlineedit_p.cpp
index 6ff40e9c50..3d8a854753 100644
--- a/src/widgets/widgets/qlineedit_p.cpp
+++ b/src/widgets/widgets/qlineedit_p.cpp
@@ -97,7 +97,7 @@ void QLineEditPrivate::_q_completionHighlighted(const QString &newText)
     } else {
         int c = control->cursor();
         QString text = control->text();
-        q->setText(text.left(c) + newText.mid(c));
+        q->setText(text.leftRef(c) + newText.midRef(c));
         control->moveCursor(control->end(), false);
 #ifndef Q_OS_ANDROID
         const bool mark = true;
diff --git a/src/widgets/widgets/qwidgetlinecontrol.cpp b/src/widgets/widgets/qwidgetlinecontrol.cpp
index a77794df8a..7fab2c1de5 100644
--- a/src/widgets/widgets/qwidgetlinecontrol.cpp
+++ b/src/widgets/widgets/qwidgetlinecontrol.cpp
@@ -1180,14 +1180,14 @@ QString QWidgetLineControl::maskString(uint pos, const QString &str, bool clear)
                     int n = findInMask(i, true, true, str[(int)strIndex]);
                     if (n != -1) {
                         if (str.length() != 1 || i == 0 || (i > 0 && (!m_maskData[i-1].separator || m_maskData[i-1].maskChar != str[(int)strIndex]))) {
-                            s += fill.mid(i, n-i+1);
+                            s += fill.midRef(i, n - i + 1);
                             i = n + 1; // update i to find + 1
                         }
                     } else {
                         // search for valid m_blank if not
                         n = findInMask(i, true, false, str[(int)strIndex]);
                         if (n != -1) {
-                            s += fill.mid(i, n-i);
+                            s += fill.midRef(i, n - i);
                             switch (m_maskData[n].caseMode) {
                             case MaskInputData::Upper:
                                 s += str[(int)strIndex].toUpper();
diff --git a/src/widgets/widgets/qwidgettextcontrol.cpp b/src/widgets/widgets/qwidgettextcontrol.cpp
index dfb1f865dc..af6d879661 100644
--- a/src/widgets/widgets/qwidgettextcontrol.cpp
+++ b/src/widgets/widgets/qwidgettextcontrol.cpp
@@ -2123,7 +2123,7 @@ QVariant QWidgetTextControl::inputMethodQuery(Qt::InputMethodQuery property, QVa
             tmpCursor.movePosition(QTextCursor::NextBlock);
             --numBlocks;
         }
-        result += block.text().mid(0,localPos);
+        result += block.text().midRef(0, localPos);
         return QVariant(result);
     }
     default: