QString: add resize(int, QChar)

This will be used in QTextStream to speed up padding processing.

[ChangeLog][QtCore][QString] Added resize(int, QChar) overload.

Change-Id: Id51f8cdacb167310157100b05cacf20e9a5d2716
Reviewed-by: Topi Reiniö <topi.reinio@theqtcompany.com>
Reviewed-by: Olivier Goffart (Woboq GmbH) <ogoffart@woboq.com>

2 files changed, 21 insertions, 3 deletions

diff --git a/src/corelib/tools/qstring.cpp b/src/corelib/tools/qstring.cpp
index 2f340477fc..4ffad7031a 100644
--- a/src/corelib/tools/qstring.cpp
+++ b/src/corelib/tools/qstring.cpp
@@ -1652,9 +1652,7 @@ QString::QString(QChar ch)
     \snippet qstring/main.cpp 45
 
     If you want to append a certain number of identical characters to
-    the string, use \l operator+=() as follows rather than resize():
-
-    \snippet qstring/main.cpp 46
+    the string, use the \l {QString::}{resize(int, QChar)} overload.
 
     If you want to expand the string so that it reaches a certain
     width and fill the new positions with a particular character, use
@@ -1694,6 +1692,25 @@ void QString::resize(int size)
     }
 }
 
+/*!
+    \overload
+    \since 5.7
+
+    Unlike \l {QString::}{resize(int)}, this overload
+    initializes the new characters to \a fillChar:
+
+    \snippet qstring/main.cpp 46
+*/
+
+void QString::resize(int size, QChar fillChar)
+{
+    const int oldSize = length();
+    resize(size);
+    const int difference = length() - oldSize;
+    if (difference > 0)
+        std::fill_n(d->begin() + oldSize, difference, fillChar.unicode());
+}
+
 /*! \fn int QString::capacity() const
 
     Returns the maximum number of characters that can be stored in
diff --git a/src/corelib/tools/qstring.h b/src/corelib/tools/qstring.h
index 75f94d7f93..9dc770d2c5 100644
--- a/src/corelib/tools/qstring.h
+++ b/src/corelib/tools/qstring.h
@@ -233,6 +233,7 @@ public:
     inline int length() const;
     inline bool isEmpty() const;
     void resize(int size);
+    void resize(int size, QChar fillChar);
 
     QString &fill(QChar c, int size = -1);
     void truncate(int pos);