Undo: implement rudimentary support for undo of dive-merging

For this, an output-parameter was added to the backend merge_dives()
function. When non-zero, instead of adding the merged dive to
the preferred trip, the preferred trip is returned to the caller.

Since the new UndoObject, just like the delete-dives UndoObject,
needs to remove/readd a set of dives, the corresponding functionality
was split-off in a helper function.

Signed-off-by: Berthold Stoeger <bstoeger@mail.tuwien.ac.at>

1 files changed, 22 insertions, 1 deletions

diff --git a/desktop-widgets/undocommands.h b/desktop-widgets/undocommands.h
index c30ae5fae..128c62e51 100644
--- a/desktop-widgets/undocommands.h
+++ b/desktop-widgets/undocommands.h
@@ -180,7 +180,7 @@ private:
 	void redo() override;
 
 	// For redo
-	QVector<struct dive*> divesToDelete;
+	std::vector<struct dive*> divesToDelete;
 
 	std::vector<OwningTripPtr> tripsToAdd;
 	std::vector<DiveToAdd> divesToAdd;
@@ -246,4 +246,25 @@ private:
 	dive		*divesToUnsplit[2];
 };
 
+class UndoMergeDives : public QUndoCommand {
+public:
+	UndoMergeDives(const QVector<dive *> &dives);
+private:
+	void undo() override;
+	void redo() override;
+
+	// For redo
+	// Add one and remove a batch of dives
+	DiveToAdd		 mergedDive;
+	std::vector<dive *>	 divesToMerge;
+
+	// For undo
+	// Remove one and add a batch of dives
+	dive			*diveToUnmerge;
+	std::vector<DiveToAdd>	 unmergedDives;
+
+	// For undo and redo
+	QVector<QPair<int, int>> divesToRenumber;
+};
+
 #endif // UNDOCOMMANDS_H