QStringList::join: add an overload taking a single QChar

This overload avoids the needless heap allocation that the traditional
overload incurs due to the implicit QChar -> QString conversion
involved there.

In order to share the implementation between the two overloads,
QStringList_join now takes the separator as a (Char*,int) tuple
instead of as a QString.

Change-Id: I92961f13a3f19099de2a6e2df9f4789a12fc83a0
Reviewed-by: João Abecasis <joao.abecasis@nokia.com>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

1 files changed, 8 insertions, 2 deletions

diff --git a/src/corelib/tools/qstringlist.h b/src/corelib/tools/qstringlist.h
index 3e63e30a57..3656b3fa40 100644
--- a/src/corelib/tools/qstringlist.h
+++ b/src/corelib/tools/qstringlist.h
@@ -75,6 +75,7 @@ public:
     inline int removeDuplicates();
 
     inline QString join(const QString &sep) const;
+    inline QString join(QChar sep) const;
 
     inline QStringList filter(const QString &str, Qt::CaseSensitivity cs = Qt::CaseSensitive) const;
     inline bool contains(const QString &str, Qt::CaseSensitivity cs = Qt::CaseSensitive) const;
@@ -122,7 +123,7 @@ Q_DECLARE_TYPEINFO(QStringList, Q_MOVABLE_TYPE);
 namespace QtPrivate {
     void Q_CORE_EXPORT QStringList_sort(QStringList *that, Qt::CaseSensitivity cs);
     int Q_CORE_EXPORT QStringList_removeDuplicates(QStringList *that);
-    QString Q_CORE_EXPORT QStringList_join(const QStringList *that, const QString &sep);
+    QString Q_CORE_EXPORT QStringList_join(const QStringList *that, const QChar *sep, int seplen);
     QStringList Q_CORE_EXPORT QStringList_filter(const QStringList *that, const QString &str,
                                                Qt::CaseSensitivity cs);
 
@@ -161,7 +162,12 @@ inline int QStringList::removeDuplicates()
 
 inline QString QStringList::join(const QString &sep) const
 {
-    return QtPrivate::QStringList_join(this, sep);
+    return QtPrivate::QStringList_join(this, sep.constData(), sep.length());
+}
+
+inline QString QStringList::join(QChar sep) const
+{
+    return QtPrivate::QStringList_join(this, &sep, 1);
 }
 
 inline QStringList QStringList::filter(const QString &str, Qt::CaseSensitivity cs) const