Initial minimal working tracerestrict implementation.

This is a port of the tracerestrict/routing restrictions feature
from TTDPatch.
At present this implements if tests (train length only),
and pathfinder deny and penalty actions.
This requires the use of YAPF. Note that restrictions are only evaluated
within the YAPF lookahead distance.

src/pathfinder/yapf/yapf_costrail.hpp

@@ -13,6 +13,7 @@
 #define YAPF_COSTRAIL_HPP
 
 #include "../../pbs.h"
+#include "../../tracerestrict.h"
 
 template <class Types>
 class CYapfCostRailT
@@ -180,6 +181,30 @@ public:
 		return 0;
 	}
 
+private:
+	// returns true if ExecuteTraceRestrict should be called
+	inline bool ShouldCheckTraceRestrict(Node& n, TileIndex tile)
+	{
+		return n.m_num_signals_passed < m_sig_look_ahead_costs.Size() &&
+				IsRestrictedSignal(tile);
+	}
+
+	// returns true if dead end bit has been set
+	inline bool ExecuteTraceRestrict(Node& n, TileIndex tile, Trackdir trackdir, int& cost, TraceRestrictProgramResult &out)
+	{
+		const TraceRestrictProgram *prog = GetExistingTraceRestrictProgram(tile, TrackdirToTrack(trackdir));
+		if (prog) {
+			prog->Execute(Yapf().GetVehicle(), out);
+			if (out.flags & TRPRF_DENY) {
+				n.m_segment->m_end_segment_reason |= ESRB_DEAD_END;
+				return true;
+			}
+			cost += out.penalty;
+		}
+		return false;
+	}
+
+public:
 	int SignalCost(Node& n, TileIndex tile, Trackdir trackdir)
 	{
 		int cost = 0;
@@ -239,6 +264,13 @@ public:
 						}
 					}
 
+					if (ShouldCheckTraceRestrict(n, tile)) {
+						TraceRestrictProgramResult out;
+						if (ExecuteTraceRestrict(n, tile, trackdir, cost, out)) {
+							return -1;
+						}
+					}
+
 					n.m_num_signals_passed++;
 					n.m_segment->m_last_signal_tile = tile;
 					n.m_segment->m_last_signal_td = trackdir;
@@ -246,6 +278,13 @@ public:
 
 				if (has_signal_against && IsPbsSignal(GetSignalType(tile, TrackdirToTrack(trackdir)))) {
 					cost += n.m_num_signals_passed < Yapf().PfGetSettings().rail_look_ahead_max_signals ? Yapf().PfGetSettings().rail_pbs_signal_back_penalty : 0;
+
+					if (ShouldCheckTraceRestrict(n, tile)) {
+						TraceRestrictProgramResult out;
+						if (ExecuteTraceRestrict(n, tile, trackdir, cost, out)) {
+							return -1;
+						}
+					}
 				}
 			}
 		}