Dive list: move sort-functionality into core

To make sorting more controlled, move all sorting functions into
the core. For this, introduce a "dive_or_trip" structure, which
represents a top-level item. Adapt the DiveTripModel accordingly.
There are now three sorting functions:
	1) dive_less_than
	2) trip_less_than
	3) dive_or_trip_less_than
These should be used by all sorting code. By moving them to a
single place, the mess can hopefully be cleaned up.

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

1 files changed, 9 insertions, 18 deletions

diff --git a/qt-models/divetripmodel.h b/qt-models/divetripmodel.h
index 4993c855f..8ff4524b3 100644
--- a/qt-models/divetripmodel.h
+++ b/qt-models/divetripmodel.h
@@ -81,24 +81,15 @@ private slots:
 private:
 	// The model has up to two levels. At the top level, we have either trips or dives
 	// that do not belong to trips. Such a top-level item is represented by the "Item"
-	// struct. Two cases two consider:
-	// 1) If "trip" is non-null, then this is a dive-trip and the dives are collected
-	// in the dives vector.  Note that in principle we could also get the dives in a
-	// trip from the backend, but there they are collected in a linked-list, which is
-	// quite inconvenient to access.
-	// 2) If "trip" is null, this is a dive and dives is supposed to contain exactly
-	// one element, which is the corresponding dive.
-	//
-	// Top-level items are ordered by timestamp. For dives, the core function
-	// dive_less_than is used, which guarantees a stable ordering even in the
-	// case of equal timestamps. For dives and trips, place dives before trips
-	// in the case of an equal timestamp. For trips with equal timestamps, the
-	// order is currently undefined. This is currently not a problem, because
-	// the core doesn't have a list of sorted trips. But nevertheless something
-	// to keep in mind.
+	// struct, which is based on the dive_or_trip structure.
+	// If it is a trip, additionally, the dives are collected in a vector.
+	// The items are ordered chronologically according to the dive_or_trip_less_than()
+	// function, which guarantees a stable ordering even in the case of equal timestamps.
+	// For dives and trips, it place dives chronologically after trips, so that in
+	// the default-descending view they are shown before trips.
 	struct Item {
-		dive_trip		*trip;
-		std::vector<dive *>	 dives;			// std::vector<> instead of QVector for insert() with three iterators
+		dive_or_trip		d_or_t;
+		std::vector<dive *>	dives;			// std::vector<> instead of QVector for insert() with three iterators
 		Item(dive_trip *t, const QVector<dive *> &dives);
 		Item(dive_trip *t, dive *d);			// Initialize a trip with one dive
 		Item(dive *d);					// Initialize a top-level dive
@@ -126,7 +117,7 @@ private:
 	void addDivesToTrip(int idx, const QVector<dive *> &dives);
 
 	dive *diveOrNull(const QModelIndex &index) const;	// Returns a dive if this index represents a dive, null otherwise
-	QPair<dive_trip *, dive *> tripOrDive(const QModelIndex &index) const;
+	dive_or_trip tripOrDive(const QModelIndex &index) const;
 								// Returns either a pointer to a trip or a dive, or twice null of index is invalid
 								// null, something is really wrong
 	void setupModelData();