Store the selected items in a more efficient way

Since Dolphin 2.0, we have stored the selected items in a QSet<int>,
which is neither space-efficient nor particularly fast when inserting
many items which are in a consecutive range.

This commit replaces the QSet<int> by a new class "KItemSet", which
stores the items in a sorted list of ranges. For each range, we only
store the first index and the length of the range, so we need a lot
less memory for most common selection patterns, and we also save quite
a few CPU cycles in many situations, because adding an item to the
KItemSet will in many cases not need a memory allocation at all, and
it's particularly easy when inserting sorted items into the KItemSet in
a row.

KItemSet contains a minimal subset of QSet's API which makes it
suitable as a drop-in replacement for our needs. It also has iterators,
such that the items can be iterated through easily, also with foreach.
One advantage of KItemSet compared to QSet<int> is that the items are
always iterated through in ascending order.

REVIEW: 113488

1 files changed, 2 insertions, 1 deletions

diff --git a/src/kitemviews/kfileitemmodel.h b/src/kitemviews/kfileitemmodel.h
index 4b50477d9..c57329fc8 100644
--- a/src/kitemviews/kfileitemmodel.h
+++ b/src/kitemviews/kfileitemmodel.h
@@ -27,6 +27,7 @@
 #include <kitemviews/private/kfileitemmodelfilter.h>
 
 #include <QHash>
+#include <QSet>
 
 class KFileItemModelDirLister;
 class QTimer;
@@ -99,7 +100,7 @@ public:
     bool showDirectoriesOnly() const;
 
     /** @reimp */
-    virtual QMimeData* createMimeData(const QSet<int>& indexes) const;
+    virtual QMimeData* createMimeData(const KItemSet& indexes) const;
 
     /** @reimp */
     virtual int indexForKeyboardSearch(const QString& text, int startFromIndex = 0) const;