From: Mikko Rasa <tdb@tdb.fi>
Date: Tue, 19 Oct 2010 16:32:20 +0000 (+0000)
Subject: Add a variant of Route::find that takes a set of tracks
X-Git-Url: https://git.tdb.fi/?a=commitdiff_plain;h=0e691a3893a07dc362c733869760e0d7d1109ea8;p=r2c2.git

Add a variant of Route::find that takes a set of tracks
Allow setting turnouts in a Route manually
Move Route::update_turnouts to its proper place
Add full route chaining to Train
Better logic for where to start pathfinding
Divert trains to an alternate route if possible when blocked
---

diff --git a/source/libmarklin/route.cpp b/source/libmarklin/route.cpp
index 6cd5841..d2ed3b7 100644
--- a/source/libmarklin/route.cpp
+++ b/source/libmarklin/route.cpp
@@ -53,13 +53,13 @@ struct TrackMatch
 	bool operator()(const Track &t) const { return &t==&track; }
 };
 
-struct TrackInRoute
+struct TrackInSet
 {
-	const Route &route;
+	const set<const Track *> &tracks;
 
-	TrackInRoute(const Route &r): route(r) { }
+	TrackInSet(const set<const Track *> &t): tracks(t) { }
 
-	bool operator()(const Track &t) const { return route.get_tracks().count(&t); }
+	bool operator()(const Track &t) const { return tracks.count(&t); }
 };
 
 template<typename Pred>
@@ -163,6 +163,72 @@ void Route::set_temporary(bool t)
 	temporary = t;
 }
 
+void Route::set_turnout(unsigned addr, unsigned path)
+{
+	if(!addr)
+		throw InvalidParameterValue("Invalid turnout address");
+	map<unsigned, int>::iterator i = turnouts.find(addr);
+	if(i==turnouts.end())
+		throw KeyError("Turnout is not in this route");
+	if(i->second>=0 && path!=static_cast<unsigned>(i->second))
+		throw InvalidState("Setting conflicts with route");
+	i->second = path;
+}
+
+void Route::update_turnouts()
+{
+	set<unsigned> found;
+	for(set<const Track *>::const_iterator i=tracks.begin(); i!=tracks.end(); ++i)
+		if(unsigned tid = (*i)->get_turnout_id())
+		{
+			found.insert(tid);
+
+			const vector<Endpoint> &endpoints = (*i)->get_type().get_endpoints();
+			const vector<Track *> &links = (*i)->get_links();
+
+			// Build a combined path mask from linked endpoints
+			unsigned mask = 15;
+			for(unsigned j=0; j<endpoints.size(); ++j)
+			{
+				if(!tracks.count(links[j]))
+					continue;
+
+				if(unsigned tid2 = links[j]->get_turnout_id())
+				{
+					const Endpoint &ep = links[j]->get_type().get_endpoints()[links[j]->get_endpoint_by_link(**i)];
+					int p = get_turnout(tid2);
+					if(p>=0 && !(ep.paths&(1<<p)))
+					{
+						// The linked track is a turnout and has a path which is incompatible with this endpoint
+						mask &= ~endpoints[j].paths;
+						continue;
+					}
+				}
+				mask &= endpoints[j].paths;
+			}
+
+			if(mask && !(mask&(mask-1)))
+			{
+				// Exactly one possible choice, set the path accordingly
+				unsigned path = 0;
+				for(; (mask && !(mask&1)); mask>>=1, ++path) ;
+				turnouts[tid] = path;
+			}
+			else if(!turnouts.count(tid))
+				// More than one possible choice, and no existing entry - set as undecided
+				turnouts[tid] = -1;
+		}
+
+	// Remove any turnouts that do not exist in the route
+	for(map<unsigned, int>::iterator i=turnouts.begin(); i!=turnouts.end();)
+	{
+		if(!found.count(i->first))
+			turnouts.erase(i++);
+		else
+			++i;
+	}
+}
+
 int Route::get_turnout(unsigned id) const
 {
 	map<unsigned, int>::const_iterator i = turnouts.find(id);
@@ -250,60 +316,6 @@ void Route::add_track_chain(const Track &start, unsigned ep, const TurnoutMap &t
 	}
 }
 
-void Route::update_turnouts()
-{
-	set<unsigned> found;
-	for(set<const Track *>::const_iterator i=tracks.begin(); i!=tracks.end(); ++i)
-		if(unsigned tid = (*i)->get_turnout_id())
-		{
-			found.insert(tid);
-
-			const vector<Endpoint> &endpoints = (*i)->get_type().get_endpoints();
-			const vector<Track *> &links = (*i)->get_links();
-
-			// Build a combined path mask from linked endpoints
-			unsigned mask = 15;
-			for(unsigned j=0; j<endpoints.size(); ++j)
-			{
-				if(!tracks.count(links[j]))
-					continue;
-
-				if(unsigned tid2 = links[j]->get_turnout_id())
-				{
-					const Endpoint &ep = links[j]->get_type().get_endpoints()[links[j]->get_endpoint_by_link(**i)];
-					int p = get_turnout(tid2);
-					if(p>=0 && !(ep.paths&(1<<p)))
-					{
-						// The linked track is a turnout and has a path which is incompatible with this endpoint
-						mask &= ~endpoints[j].paths;
-						continue;
-					}
-				}
-				mask &= endpoints[j].paths;
-			}
-
-			if(mask && !(mask&(mask-1)))
-			{
-				// Exactly one possible choice, set the path accordingly
-				unsigned path = 0;
-				for(; (mask && !(mask&1)); mask>>=1, ++path) ;
-				turnouts[tid] = path;
-			}
-			else if(!turnouts.count(tid))
-				// More than one possible choice, and no existing entry - set as undecided
-				turnouts[tid] = -1;
-		}
-
-	// Remove any turnouts that do not exist in the route
-	for(map<unsigned, int>::iterator i=turnouts.begin(); i!=turnouts.end();)
-	{
-		if(!found.count(i->first))
-			turnouts.erase(i++);
-		else
-			++i;
-	}
-}
-
 void Route::save(list<DataFile::Statement> &st) const
 {
 	st.push_back((DataFile::Statement("name"), name));
@@ -375,7 +387,12 @@ Route *Route::find(const Track &from, unsigned ep, const Track &to)
 
 Route *Route::find(const Track &from, unsigned ep, const Route &to)
 {
-	return create_route(from, ep, TrackInRoute(to));
+	return create_route(from, ep, TrackInSet(to.get_tracks()));
+}
+
+Route *Route::find(const Track &from, unsigned ep, const set<const Track *> &to)
+{
+	return create_route(from, ep, TrackInSet(to));
 }
 
 
diff --git a/source/libmarklin/route.h b/source/libmarklin/route.h
index 7c188b0..3825c7e 100644
--- a/source/libmarklin/route.h
+++ b/source/libmarklin/route.h
@@ -53,6 +53,7 @@ public:
 	const std::string &get_name() const { return name; }
 	void set_temporary(bool);
 	bool is_temporary() const { return temporary; }
+	void set_turnout(unsigned, unsigned);
 	void update_turnouts();
 	int get_turnout(unsigned) const;
 	const std::map<unsigned, int> &get_turnouts() const { return turnouts; }
@@ -68,6 +69,7 @@ private:
 public:
 	static Route *find(const Track &, unsigned, const Track &);
 	static Route *find(const Track &, unsigned, const Route &);
+	static Route *find(const Track &, unsigned, const std::set<const Track *> &);
 };
 
 } // namespace Marklin
diff --git a/source/libmarklin/train.cpp b/source/libmarklin/train.cpp
index bd813d3..baa58db 100644
--- a/source/libmarklin/train.cpp
+++ b/source/libmarklin/train.cpp
@@ -55,8 +55,6 @@ Train::Train(Layout &l, const VehicleType &t, unsigned a):
 	speed_changing(false),
 	reverse(false),
 	functions(0),
-	route(0),
-	next_route(0),
 	end_of_route(false),
 	status("Unplaced"),
 	travel_dist(0),
@@ -207,35 +205,29 @@ void Train::set_timetable(Timetable *tt)
 
 void Train::set_route(const Route *r)
 {
-	if(!rsv_blocks.empty())
-	{
-		for(list<BlockRef>::iterator i=rsv_blocks.begin(); i!=rsv_blocks.end(); ++i)
-			if(i->block->get_sensor_id())
-			{
-				release_blocks(rsv_blocks, ++i, rsv_blocks.end());
-				break;
-			}
-	}
+	free_noncritical_blocks();
 
-	route = r;
-	next_route = 0;
+	routes.clear();
+	if(r)
+		routes.push_back(r);
 	end_of_route = false;
 
-	if(route && !cur_blocks.empty())
+	if(r && !cur_blocks.empty())
 	{
 		BlockRef &last = (rsv_blocks.empty() ? cur_blocks.back() : rsv_blocks.back());
 		BlockRef next = last.next();
 		const Block::Endpoint &ep = next.block->get_endpoints()[next.entry];
-		if(!route->get_tracks().count(ep.track))
-		{
-			next_route = route;
-			route = Route::find(*ep.track, ep.track_ep, *next_route);
-		}
+		if(!r->get_tracks().count(ep.track))
+			routes.push_front(Route::find(*ep.track, ep.track_ep, *r));
+
+		/* XXX This is sort of a hack, but it keeps divert() happy.  Need to come
+		up with a better solution when there is time. */
+		routes.push_front(create_lead_route());
 	}
 
 	reserve_more();
 
-	signal_route_changed.emit(route);
+	signal_route_changed.emit(get_route());
 }
 
 void Train::go_to(const Track &to)
@@ -248,20 +240,138 @@ void Train::go_to(const Track &to)
 			return;
 		}
 
-	BlockRef *last = 0;
-	if(rsv_blocks.empty())
-		last = &cur_blocks.back();
+	free_noncritical_blocks();
+
+	BlockRef &last = (rsv_blocks.empty() ? cur_blocks.back() : rsv_blocks.back());
+	BlockRef next = last.next();
+	const Block::Endpoint &ep = next.block->get_endpoints()[next.entry];
+
+	set_route(Route::find(*ep.track, ep.track_ep, to));
+}
+
+bool Train::divert(Track &from)
+{
+	if(!from.get_turnout_id())
+		throw InvalidParameterValue("Can't divert from a non-turnout");
+	if(routes.empty())
+		return false;
+
+	int path = -1;
+	unsigned from_ep = 0;
+	list<RouteRef>::iterator route = routes.begin();
+	Block *block = cur_blocks.back().block;
+	unsigned entry = cur_blocks.back().entry;
+	set<const Track *> visited;
+
+	// Follow our routes to find out where we're entering the turnout
+	while(1)
+	{
+		Block *link = block->get_link(block->traverse(entry, route->route));
+		entry = link->get_endpoint_by_link(*block);
+		block = link;
+
+		const Block::Endpoint &entry_ep = block->get_endpoints()[entry];
+
+		if(visited.count(entry_ep.track))
+			return false;
+		visited.insert(entry_ep.track);
+
+		if(!advance_route(route, *entry_ep.track))
+			return false;
+
+		if(entry_ep.track==&from)
+		{
+			if(block->get_train()==this && !free_block(*block))
+				return false;
+
+			from_ep = entry_ep.track_ep;
+			path = route->route->get_turnout(from.get_turnout_id());
+			break;
+		}
+	}
+
+	// Check that more than one path is available
+	unsigned ep_paths = from.get_type().get_endpoints()[from_ep].paths;
+	if(!(ep_paths&(ep_paths-1)))
+		return false;
+
+	// Choose some other path
+	for(int i=0; ep_paths>>i; ++i)
+		if((ep_paths&(1<<i)) && i!=path)
+		{
+			path = i;
+			break;
+		}
+
+	Track *track = from.get_link(from.traverse(from_ep, path));
+	if(!track)
+		return false;
+
+	unsigned ep = track->get_endpoint_by_link(from);
+
+	set<const Track *> tracks;
+	for(list<RouteRef>::iterator i=routes.begin(); i!=routes.end(); ++i)
+		tracks.insert(i->route->get_tracks().begin(), i->route->get_tracks().end());
+	Route *diversion = 0;
+	try
+	{
+		diversion = Route::find(*track, ep, tracks);
+	}
+	catch(const Msp::Exception &)
+	{
+		return false;
+	}
+
+	diversion->set_name("Diversion");
+	diversion->add_track(from);
+	diversion->set_turnout(from.get_turnout_id(), path);
+
+	if(!is_valid_diversion(*diversion, from, from_ep))
+	{
+		delete diversion;
+		return false;
+	}
+
+	// Follow the diversion route until we get back to the original route
+	list<RouteRef>::iterator end = routes.end();
+	while(1)
+	{
+		path = 0;
+		if(track->get_turnout_id())
+			path = diversion->get_turnout(track->get_turnout_id());
+		Track *next = track->get_link(track->traverse(ep, path));
+
+		for(list<RouteRef>::iterator i=route; (end==routes.end() && i!=routes.end()); ++i)
+			if(i->route->get_tracks().count(next))
+				end = i;
+
+		if(end!=routes.end())
+			break;
+		else if(!diversion->get_tracks().count(next))
+			throw Exception("Pathfinder returned a bad route");
+
+		ep = next->get_endpoint_by_link(*track);
+		track = next;
+	}
+
+	if(route==end)
+		// We are rejoining the same route we diverted from, duplicate it
+		routes.insert(end, *route);
 	else
 	{
-		for(list<BlockRef>::iterator i=rsv_blocks.begin(); (i!=rsv_blocks.end() && !last); ++i)
-			if(i->block->get_sensor_id())
-				last = &*i;
+		++route;
+		routes.erase(route, end);
 	}
+	routes.insert(end, RouteRef(diversion, from.get_turnout_id()));
 
-	BlockRef next = last->next();
-	const Block::Endpoint &ep = next.block->get_endpoints()[next.entry];
+	return true;
+}
 
-	set_route(Route::find(*ep.track, ep.track_ep, to));
+const Route *Train::get_route() const
+{
+	if(routes.empty())
+		return 0;
+	return routes.front().route;
 }
 
 void Train::place(Block &block, unsigned entry)
@@ -337,6 +447,75 @@ bool Train::free_block(Block &block)
 	return false;
 }
 
+void Train::free_noncritical_blocks()
+{
+	if(cur_blocks.empty() || rsv_blocks.empty())
+		return;
+
+	if(controller->get_speed()==0)
+	{
+		release_blocks(rsv_blocks);
+		return;
+	}
+
+	float margin = 10*layout.get_catalogue().get_scale();
+	float min_dist = controller->get_braking_distance()*1.3+margin;
+
+	Vehicle &veh = *(reverse ? vehicles.back() : vehicles.front());
+
+	Track *track = veh.get_track();
+	list<BlockRef>::iterator block = cur_blocks.begin();
+	bool in_rsv = false;
+	while(block!=rsv_blocks.end() && !block->block->get_tracks().count(track))
+	{
+		++block;
+		if(block==cur_blocks.end())
+		{
+			block = rsv_blocks.begin();
+			in_rsv = true;
+		}
+	}
+
+	unsigned entry = veh.get_entry();
+	float dist = veh.get_offset();
+	if(reverse)
+		entry = track->traverse(entry);
+	else
+		dist = track->get_type().get_path_length(track->get_active_path())-dist;
+	dist -= veh.get_type().get_length()/2;
+
+	bool nsens = 0;
+	while(1)
+	{
+		Track *next = track->get_link(track->traverse(entry));
+		entry = next->get_endpoint_by_link(*track);
+		track = next;
+
+		if(!block->block->get_tracks().count(track))
+		{
+			++block;
+			if(block==cur_blocks.end())
+			{
+				block = rsv_blocks.begin();
+				in_rsv = true;
+			}
+			if(block==rsv_blocks.end())
+				return;
+
+			if(dist>min_dist && nsens>0)
+			{
+				release_blocks(rsv_blocks, block, rsv_blocks.end());
+				return;
+			}
+
+			if(in_rsv && block->block->get_sensor_id())
+				++nsens;
+		}
+
+		dist += track->get_type().get_path_length(track->get_active_path());
+	}
+}
+
 int Train::get_entry_to_block(Block &block) const
 {
 	for(list<BlockRef>::const_iterator i=cur_blocks.begin(); i!=cur_blocks.end(); ++i)
@@ -435,7 +614,7 @@ void Train::tick(const Time::TimeStamp &t, const Time::TimeDelta &dt)
 		if(dist>10*layout.get_catalogue().get_scale())
 		{
 			cur_blocks.front().block->reserve(0);
-			cur_blocks.erase(cur_blocks.begin());
+			cur_blocks.pop_front();
 		}
 	}
 }
@@ -467,12 +646,12 @@ void Train::save(list<DataFile::Statement> &st) const
 			st.push_back((DataFile::Statement("block"), i->block->get_id()));
 	}
 
-	if(route)
+	if(!routes.empty())
 	{
-		if(!route->is_temporary())
-			st.push_back((DataFile::Statement("route"), route->get_name()));
-		else if(next_route && !next_route->is_temporary())
-			st.push_back((DataFile::Statement("route"), next_route->get_name()));
+		list<RouteRef>::const_iterator i = routes.begin();
+		for(; (i!=routes.end() && i->route->is_temporary()); ++i) ;
+		if(i!=routes.end())
+			st.push_back((DataFile::Statement("route"), i->route->get_name()));
 	}
 
 	if(timetable)
@@ -577,16 +756,15 @@ void Train::sensor_event(unsigned addr, bool state)
 			overshoot_dist = 0;
 
 			// Check if we've reached the next route
-			if(next_route)
+			if(routes.size()>1)
 			{
-				const set<const Track *> &rtracks = next_route->get_tracks();
+				const set<const Track *> &rtracks = (++routes.begin())->route->get_tracks();
 				for(list<BlockRef>::iterator j=rsv_blocks.begin(); j!=i; ++j)
 					if(rtracks.count(j->block->get_endpoints()[j->entry].track))
 					{
-						route = next_route;
-						next_route = 0;
+						routes.pop_front();
 						// XXX Exceptions?
-						signal_route_changed.emit(route);
+						signal_route_changed.emit(routes.front().route);
 						break;
 					}
 			}
@@ -631,7 +809,7 @@ void Train::sensor_event(unsigned addr, bool state)
 
 void Train::turnout_event(unsigned addr, bool)
 {
-	if(pending_block)
+	if(pending_block && (!pending_block->get_train() || pending_block->get_train()==this))
 	{
 		unsigned pending_addr = pending_block->get_turnout_id();
 		bool double_addr = (*pending_block->get_tracks().begin())->get_type().is_double_address();
@@ -690,24 +868,16 @@ unsigned Train::reserve_more()
 	if(end_of_route)
 		return nsens;
 
-	const Route *cur_route = 0;
-	if(route)
-	{
-		const set<Track *> &tracks = start->block->get_tracks();
-		for(set<Track *>::const_iterator i=tracks.begin(); (cur_route!=route && i!=tracks.end()); ++i)
-		{
-			if(route->get_tracks().count(*i))
-				cur_route = route;
-			else if(next_route && next_route->get_tracks().count(*i))
-				cur_route = next_route;
-		}
-	}
+	list<RouteRef>::iterator cur_route = routes.begin();
+	advance_route(cur_route, *start->block->get_endpoints()[start->entry].track);
 
 	float approach_margin = 50*layout.get_catalogue().get_scale();
 	float min_dist = controller->get_braking_distance()*1.3+approach_margin*2;
 
 	BlockRef *last = start;
 	BlockRef *good = start;
+	Track *divert_track = 0;
+	bool try_divert = false;
 	unsigned good_sens = nsens;
 	float good_dist = dist;
 	Train *blocking_train = 0;
@@ -719,8 +889,12 @@ unsigned Train::reserve_more()
 	{
 		// Traverse to the next block
 		float length = 0;
-		unsigned exit = last->block->traverse(last->entry, cur_route, &length);
-		Block *link = last->block->get_link(exit);
+		Block *link = 0;
+		{
+			const Route *route = (cur_route!=routes.end() ? cur_route->route : 0);
+			unsigned exit = last->block->traverse(last->entry, route, &length);
+			link = last->block->get_link(exit);
+		}
 		if(!link)
 			break;
 
@@ -730,11 +904,9 @@ unsigned Train::reserve_more()
 
 		const Block::Endpoint &entry_ep = link->get_endpoints()[entry];
 
-		if(cur_route)
+		if(cur_route!=routes.end())
 		{
-			if(cur_route!=next_route && next_route && next_route->get_tracks().count(entry_ep.track))
-				cur_route = next_route;
-			else if(!cur_route->get_tracks().count(entry_ep.track))
+			if(!advance_route(cur_route, *entry_ep.track))
 			{
 				// Keep the blocks if we arrived at the end of the route
 				if(!blocking_train)
@@ -747,8 +919,8 @@ unsigned Train::reserve_more()
 				break;
 			}
 		}
-		else if(route && route->get_tracks().count(entry_ep.track))
-			cur_route = route;
+		else if(!routes.empty() && routes.front().route->get_tracks().count(entry_ep.track))
+			cur_route = routes.begin();
 
 		if(link->get_endpoints().size()<2)
 		{
@@ -765,11 +937,12 @@ unsigned Train::reserve_more()
 		{
 			if(link->get_train()!=blocking_train)
 			{
-				// XXX is it possible that this won't free all the blocks we want?
 				if(blocking_train->free_block(*contested_blocks.back().block))
 				{
 					// Roll back and start actually reserving the blocks
 					last = &rsv_blocks.back();
+					cur_route = routes.begin();
+					advance_route(cur_route, *last->block->get_endpoints()[last->entry].track);
 					if(blocking_train->get_priority()==priority)
 						blocking_train->yield_to(*this);
 					blocking_train = 0;
@@ -777,7 +950,9 @@ unsigned Train::reserve_more()
 				}
 				else
 				{
+					yield_to(*blocking_train);
 					pending_block = contested_blocks.front().block;
+					try_divert = divert_track;
 					break;
 				}
 			}
@@ -801,24 +976,27 @@ unsigned Train::reserve_more()
 			if(other_entry<0)
 				throw LogicError("Block reservation inconsistency");
 
-			int other_prio = other_train->get_priority();
-
 			bool entry_conflict = (static_cast<unsigned>(entry)==link->traverse(other_entry));
 			bool exit_conflict = (link->traverse(entry)==static_cast<unsigned>(other_entry));
-			if(!entry_conflict && !exit_conflict)
+			if(!entry_conflict && !last->block->get_turnout_id())
 			{
-				/* Same direction, keep the blocks we got so far and wait for the
-				other train to pass */
+				/* The other train is not coming to the blocks we're holding, so we
+				can keep them. */
 				good = last;
 				good_sens = nsens;
 				good_dist = dist;
+			}
+
+			int other_prio = other_train->get_priority();
 
-				// Ask a lesser priority train to free the block for us
-				if(other_train->get_priority()<priority)
-					if(other_train->free_block(*link))
-						reserved = link->reserve(this);
+			if(!entry_conflict && !exit_conflict && other_prio<priority)
+			{
+				/* Ask a lesser priority train going to the same direction to free
+				the block for us */
+				if(other_train->free_block(*link))
+					reserved = link->reserve(this);
 			}
-			else if(other_prio<priority || (other_prio==priority && other_train!=yielding_to && entry_conflict))
+			else if(other_train!=yielding_to && (other_prio<priority || (other_prio==priority && entry_conflict)))
 			{
 				/* A lesser priority train is coming at us, we must ask it to free
 				enough blocks to get clear of it to avoid a potential deadlock */
@@ -828,6 +1006,9 @@ unsigned Train::reserve_more()
 				last = &contested_blocks.back();
 				continue;
 			}
+			else if(divert_track && (entry_conflict || exit_conflict))
+				// We are blocked, but there's a diversion possibility
+				try_divert = true;
 
 			if(!reserved)
 			{
@@ -839,22 +1020,29 @@ unsigned Train::reserve_more()
 		if(link->get_turnout_id())
 		{
 			const Endpoint &track_ep = entry_ep.track->get_type().get_endpoints()[entry_ep.track_ep];
+			bool multiple_paths = (track_ep.paths&(track_ep.paths-1));
 
-			// Keep the blocks reserved so far, as either us or the other train can diverge
-			good = last;
-			good_sens = nsens;
-			good_dist = dist;
+			if(multiple_paths || !last->block->get_turnout_id())
+			{
+				/* We can keep the blocks reserved so far if we are facing the
+				points or if there was no turnout immediately before this one.
+				With multiple successive turnouts (as is common in crossovers) it's
+				best to hold at one we can divert from. */
+				good = last;
+				good_sens = nsens;
+				good_dist = dist;
+			}
 
 			// Figure out what path we'd like to take on the turnout
 			int path = -1;
-			if(cur_route)
-				path = cur_route->get_turnout(link->get_turnout_id());
+			for(list<RouteRef>::iterator i=cur_route; (path<0 && i!=routes.end()); ++i)
+				path = i->route->get_turnout(link->get_turnout_id());
 			if(path<0)
 				path = entry_ep.track->get_active_path();
-			if(!((track_ep.paths>>path)&1))
+			if(!(track_ep.paths&(1<<path)))
 			{
 				for(unsigned i=0; track_ep.paths>>i; ++i)
-					if((track_ep.paths>>i)&1)
+					if(track_ep.paths&(1<<i))
 						path = i;
 			}
 
@@ -869,6 +1057,11 @@ unsigned Train::reserve_more()
 					break;
 				}
 			}
+
+			if(multiple_paths && cur_route!=routes.end() && cur_route->diversion!=link->get_turnout_id())
+				/* There's multiple paths to be taken and we are on a route - take
+				note of the diversion possibility */
+				divert_track = entry_ep.track;
 		}
 
 		if(!contested_blocks.empty() && contested_blocks.front().block==link)
@@ -886,7 +1079,7 @@ unsigned Train::reserve_more()
 	while(!rsv_blocks.empty() && &rsv_blocks.back()!=good)
 	{
 		rsv_blocks.back().block->reserve(0);
-		rsv_blocks.erase(--rsv_blocks.end());
+		rsv_blocks.pop_back();
 	}
 
 	if(!rsv_blocks.empty() && &rsv_blocks.back()!=start)
@@ -899,6 +1092,9 @@ unsigned Train::reserve_more()
 	if(i!=rsv_blocks.begin())
 		cur_blocks.splice(cur_blocks.end(), rsv_blocks, rsv_blocks.begin(), i);
 
+	if(try_divert && divert(*divert_track))
+		return reserve_more();
+
 	return good_sens;
 }
 
@@ -1072,6 +1268,94 @@ void Train::reverse_blocks(list<BlockRef> &blocks) const
 		i->entry = i->block->traverse(i->entry);
 }
 
+bool Train::advance_route(list<RouteRef>::iterator &iter, const Track &track)
+{
+	while(iter!=routes.end() && !iter->route->get_tracks().count(&track))
+		++iter;
+	if(iter==routes.end())
+		return false;
+
+	list<RouteRef>::iterator next = iter;
+	++next;
+	if(next!=routes.end() && next->diversion && next->route->get_tracks().count(&track))
+		iter = next;
+
+	return true;
+}
+
+Route *Train::create_lead_route()
+{
+	Route *lead = new Route(layout);
+	lead->set_name("Lead");
+	lead->set_temporary(true);
+
+	for(list<BlockRef>::iterator i=cur_blocks.begin(); i!=rsv_blocks.end(); )
+	{
+		// XXX Make Route eat non-const tracks to get rid of this idiocy and various const_casts
+		const set<Track *> &btracks = i->block->get_tracks();
+		set<const Track *> tracks(btracks.begin(), btracks.end());
+		lead->add_tracks(tracks);
+
+		if(++i==cur_blocks.end())
+			i = rsv_blocks.begin();
+	}
+
+	return lead;
+}
+
+bool Train::is_valid_diversion(const Route &diversion, const Track &from, unsigned from_ep)
+{
+	float diversion_len = 0;
+	const Track *track = &from;
+	unsigned ep = from_ep;
+	while(diversion.get_tracks().count(track))
+	{
+		unsigned path = 0;
+		if(track->get_turnout_id())
+			path = diversion.get_turnout(track->get_turnout_id());
+		diversion_len += track->get_type().get_path_length(path);
+
+		const Track *next = track->get_link(track->traverse(ep, path));
+		ep = next->get_endpoint_by_link(*track);
+		track = next;
+
+		if(track==&from)
+			return false;
+	}
+
+	list<RouteRef>::iterator route = routes.begin();
+	if(!advance_route(route, from))
+		return false;
+
+	set<const Track *> visited;
+	float route_len = 0;
+	track = &from;
+	ep = from_ep;
+	while(1)
+	{
+		unsigned path = 0;
+		if(track->get_turnout_id())
+			path = route->route->get_turnout(track->get_turnout_id());
+		route_len += track->get_type().get_path_length(path);
+
+		if(track!=&from && diversion.get_tracks().count(track))
+			break;
+
+		if(visited.count(track))
+			return false;
+		visited.insert(track);
+
+		const Track *next = track->get_link(track->traverse(ep, path));
+		ep = next->get_endpoint_by_link(*track);
+		track = next;
+
+		if(!advance_route(route, *track))
+			return false;
+	}
+
+	return diversion_len<route_len*1.2;
+}
+
 
 Train::BlockRef::BlockRef(Block *b, unsigned e):
 	block(b),
@@ -1092,6 +1376,12 @@ Train::BlockRef Train::BlockRef::next() const
 }
 
 
+Train::RouteRef::RouteRef(const Route *r, unsigned d):
+	route(r),
+	diversion(d)
+{ }
+
+
 Train::RealSpeed::RealSpeed():
 	speed(0),
 	weight(0)
diff --git a/source/libmarklin/train.h b/source/libmarklin/train.h
index 02d1d52..e675c4b 100644
--- a/source/libmarklin/train.h
+++ b/source/libmarklin/train.h
@@ -60,6 +60,14 @@ private:
 		BlockRef next() const;
 	};
 
+	struct RouteRef
+	{
+		const Route *route;
+		unsigned diversion;
+
+		RouteRef(const Route *, unsigned = 0);
+	};
+
 	struct RealSpeed
 	{
 		float speed;
@@ -89,8 +97,7 @@ private:
 	bool reverse;
 	Msp::Time::TimeStamp stop_timeout;
 	unsigned functions;
-	const Route *route;
-	const Route *next_route;
+	std::list<RouteRef> routes;
 	bool end_of_route;
 	std::string status;
 
@@ -135,11 +142,13 @@ public:
 
 	void set_route(const Route *);
 	void go_to(const Track &);
-	const Route *get_route() const { return route; }
+	bool divert(Track &);
+	const Route *get_route() const;
 	void place(Block &, unsigned);
 	void unplace();
 	bool is_placed() const { return !cur_blocks.empty(); }
 	bool free_block(Block &);
+	void free_noncritical_blocks();
 	int get_entry_to_block(Block &) const;
 	float get_reserved_distance() const;
 
@@ -165,6 +174,9 @@ private:
 	void release_blocks(std::list<BlockRef> &);
 	void release_blocks(std::list<BlockRef> &, std::list<BlockRef>::iterator, std::list<BlockRef>::iterator);
 	void reverse_blocks(std::list<BlockRef> &) const;
+	bool advance_route(std::list<RouteRef>::iterator &, const Track &);
+	Route *create_lead_route();
+	bool is_valid_diversion(const Route &, const Track &, unsigned);
 };
 
 } // namespace Marklin