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, 3 insertions, 3 deletions

diff --git a/src/views/dolphinview.h b/src/views/dolphinview.h
index a6f969bc1..b43957f22 100644
--- a/src/views/dolphinview.h
+++ b/src/views/dolphinview.h
@@ -34,7 +34,6 @@
 #include <QBoxLayout>
 #include <QKeyEvent>
 #include <QLinkedList>
-#include <QSet>
 #include <QWidget>
 
 typedef KIO::FileUndoManager::CommandType CommandType;
@@ -45,6 +44,7 @@ class KActionCollection;
 class KFileItemModel;
 class KItemListContainer;
 class KItemModelBase;
+class KItemSet;
 class KUrl;
 class ToolTipManager;
 class VersionControlObserver;
@@ -563,7 +563,7 @@ private slots:
     void activate();
 
     void slotItemActivated(int index);
-    void slotItemsActivated(const QSet<int>& indexes);
+    void slotItemsActivated(const KItemSet& indexes);
     void slotItemMiddleClicked(int index);
     void slotItemContextMenuRequested(int index, const QPointF& pos);
     void slotViewContextMenuRequested(const QPointF& pos);
@@ -587,7 +587,7 @@ private slots:
      * the signal is emitted only after no selection change has been done
      * within a small delay.
      */
-    void slotSelectionChanged(const QSet<int>& current, const QSet<int>& previous);
+    void slotSelectionChanged(const KItemSet& current, const KItemSet& previous);
 
     /**
      * Is called by emitDelayedSelectionChangedSignal() and emits the