From 8c31771a3252f3717ce53fd33567c74003c7cd1a Mon Sep 17 00:00:00 2001
From: Mikko Rasa <tdb@tdb.fi>
Date: Sun, 30 Mar 2014 15:35:34 +0300
Subject: [PATCH] Start refactoring TrainRoutePlanner

OOP calls for the logic to be close to the data it uses, so let's put it
there.
---
 source/libr2c2/trainrouteplanner.cpp | 147 ++++++++++++++++-----------
 source/libr2c2/trainrouteplanner.h   |   6 +-
 2 files changed, 92 insertions(+), 61 deletions(-)

diff --git a/source/libr2c2/trainrouteplanner.cpp b/source/libr2c2/trainrouteplanner.cpp
index c5519e4..f517afd 100644
--- a/source/libr2c2/trainrouteplanner.cpp
+++ b/source/libr2c2/trainrouteplanner.cpp
@@ -40,7 +40,7 @@ void TrainRoutePlanner::plan()
 
 		if(update_states(*i))
 		{
-			int next_train = find_next_train(*i);
+			int next_train = i->find_next_train();
 			if(next_train>=0)
 				add_steps(*i, next_train);
 		}
@@ -53,65 +53,16 @@ void TrainRoutePlanner::plan()
 bool TrainRoutePlanner::update_states(RoutingStep &step)
 {
 	RoutingStep next(&step);
-	bool changes = false;
-	for(vector<TrainRoutingState>::iterator i=next.trains.begin(); i!=next.trains.end(); ++i)
-	{
-		if(i->state==ARRIVED)
-			continue;
-
-		TrainState old_state = i->state;
-		if(i->state==BLOCKED)
-			i->state = MOVING;
-
-		TrackIter next_track = i->track.next(i->path);
-		if(!next_track)
-			return false;
-
-		for(vector<TrainRoutingState>::iterator j=next.trains.begin(); j!=next.trains.end(); ++j)
-			if(j!=i)
-			{
-				if(j->track.track()==next_track.track())
-				{
-					unsigned other_exit = j->track.reverse(j->path).entry();
-					if(next_track.entry()==other_exit)
-						return false;
-				}
-				else if(!j->is_occupied(*next_track))
-					continue;
+	if(!next.update_states())
+		return true;
+	if(next.check_deadlocks())
+		return false;
 
-				i->state = BLOCKED;
-			}
-
-		if(i->state!=old_state)
-			changes = true;
-	}
-
-	if(changes)
-	{
-		list<RoutingStep>::iterator i;
-		for(i=steps.begin(); (i!=steps.end() && !(next<*i)); ++i) ;
-		steps.insert(i, next);
-	}
-
-	return !changes;
-}
+	list<RoutingStep>::iterator i;
+	for(i=steps.begin(); (i!=steps.end() && !(next<*i)); ++i) ;
+	steps.insert(i, next);
 
-int TrainRoutePlanner::find_next_train(RoutingStep &step)
-{
-	Time::TimeDelta min_dt;
-	int next_train = -1;
-	for(unsigned i=0; i<step.trains.size(); ++i)
-		if(step.trains[i].state==MOVING)
-		{
-			Time::TimeDelta dt = step.trains[i].get_time_to_next_track();
-			if(dt<min_dt || next_train<0)
-			{
-				min_dt = dt;
-				next_train = i;
-			}
-		}
-
-	return next_train;
+	return false;
 }
 
 void TrainRoutePlanner::add_steps(RoutingStep &step, unsigned train_index)
@@ -244,7 +195,8 @@ TrainRoutePlanner::TrainRoutingState::TrainRoutingState(TrainRoutingInfo &inf):
 	occupied_tracks(0),
 	state(MOVING),
 	delay(info->router->get_departure_delay()),
-	waypoint(info->router->get_n_waypoints() ? 0 : -1)
+	waypoint(info->router->get_n_waypoints() ? 0 : -1),
+	blocked_by(-1)
 {
 	const Vehicle *veh = &info->train->get_vehicle(0);
 	// TODO margins
@@ -277,7 +229,8 @@ TrainRoutePlanner::TrainRoutingState::TrainRoutingState(const TrainRoutingState
 	back_offset(other.back_offset),
 	state(other.state),
 	delay(other.delay),
-	waypoint(other.waypoint)
+	waypoint(other.waypoint),
+	blocked_by(other.blocked_by)
 {
 	++occupied_tracks->refcount;
 }
@@ -345,6 +298,80 @@ TrainRoutePlanner::RoutingStep::RoutingStep(RoutingStep *p):
 	prev(p)
 { }
 
+bool TrainRoutePlanner::RoutingStep::update_states()
+{
+	bool changes = false;
+	for(vector<TrainRoutingState>::iterator i=trains.begin(); i!=trains.end(); ++i)
+	{
+		if(i->state==ARRIVED)
+			continue;
+
+		TrainState old_state = i->state;
+
+		TrackIter next_track = i->track.next(i->path);
+		if(next_track)
+		{
+			i->blocked_by = get_occupant(*next_track);
+			if(i->blocked_by>=0)
+				i->state = BLOCKED;
+			else if(i->state==BLOCKED)
+				i->state = MOVING;
+		}
+		else
+			i->state = BLOCKED;
+
+		if(i->state!=old_state)
+			changes = true;
+	}
+
+	return changes;
+}
+
+bool TrainRoutePlanner::RoutingStep::check_deadlocks() const
+{
+	for(unsigned i=0; i<trains.size(); ++i)
+	{
+		const TrainRoutingState &train = trains[i];
+		if(train.state!=BLOCKED)
+			continue;
+
+		if(train.blocked_by<0)
+			return true;
+
+		if(trains[train.blocked_by].blocked_by==static_cast<int>(i))
+			return true;
+	}
+
+	return false;
+}
+
+int TrainRoutePlanner::RoutingStep::get_occupant(Track &track) const
+{
+	for(unsigned i=0; i<trains.size(); ++i)
+		if(trains[i].is_occupied(track))
+			return i;
+
+	return -1;
+}
+
+int TrainRoutePlanner::RoutingStep::find_next_train() const
+{
+	Time::TimeDelta min_dt;
+	int next_train = -1;
+	for(unsigned i=0; i<trains.size(); ++i)
+		if(trains[i].state==MOVING)
+		{
+			Time::TimeDelta dt = trains[i].get_time_to_next_track();
+			if(dt<min_dt || next_train<0)
+			{
+				min_dt = dt;
+				next_train = i;
+			}
+		}
+
+	return next_train;
+}
+
 void TrainRoutePlanner::RoutingStep::advance(const Time::TimeDelta &dt)
 {
 	time += dt;
diff --git a/source/libr2c2/trainrouteplanner.h b/source/libr2c2/trainrouteplanner.h
index b241150..f50669c 100644
--- a/source/libr2c2/trainrouteplanner.h
+++ b/source/libr2c2/trainrouteplanner.h
@@ -62,6 +62,7 @@ private:
 		TrainState state;
 		Msp::Time::TimeDelta delay;
 		int waypoint;
+		int blocked_by;
 
 		TrainRoutingState(TrainRoutingInfo &);
 		TrainRoutingState(const TrainRoutingState &);
@@ -82,6 +83,10 @@ private:
 		RoutingStep();
 		RoutingStep(RoutingStep *);
 
+		bool update_states();
+		bool check_deadlocks() const;
+		int get_occupant(Track &) const;
+		int find_next_train() const;
 		void advance(const Msp::Time::TimeDelta &);
 		bool is_viable() const;
 		bool is_goal() const;
@@ -98,7 +103,6 @@ public:
 	void plan();
 private:
 	bool update_states(RoutingStep &);
-	int find_next_train(RoutingStep &);
 	void add_steps(RoutingStep &, unsigned);
 	void add_waiting_step(RoutingStep &, unsigned);
 	void add_steps(RoutingStep &, TrainRoutingState &train);
-- 
2.45.2