yapf_rail.cpp

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/*
 * This file is part of OpenTTD.
 * OpenTTD is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, version 2.
 * OpenTTD is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 * See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with OpenTTD. If not, see <http://www.gnu.org/licenses/>.
 */
 
#include "../../stdafx.h"
 
#include "yapf.hpp"
#include "yapf_cache.h"
#include "yapf_node_rail.hpp"
#include "yapf_costrail.hpp"
#include "yapf_destrail.hpp"
#include "../../viewport_func.h"
#include "../../newgrf_station.h"
 
#include "../../safeguards.h"
 
template <typename Tpf> void DumpState(Tpf &pf1, Tpf &pf2)
{
  DumpTarget dmp1, dmp2;
  pf1.DumpBase(dmp1);
  pf2.DumpBase(dmp2);
  auto f1 = FileHandle::Open("yapf1.txt", "wt");
  auto f2 = FileHandle::Open("yapf2.txt", "wt");
  assert(f1.has_value());
  assert(f2.has_value());
  fwrite(dmp1.m_out.c_str(), 1, dmp1.m_out.size(), *f1);
  fwrite(dmp2.m_out.c_str(), 1, dmp2.m_out.size(), *f2);
}
 
template <class Types>
class CYapfReserveTrack
{
public:
  typedef typename Types::Tpf Tpf;                     
  typedef typename Types::TrackFollower TrackFollower;
  typedef typename Types::NodeList::Titem Node;        
 
protected:
  inline Tpf &Yapf()
  {
    return *static_cast<Tpf *>(this);
  }
 
private:
  TileIndex m_res_dest;         
  Trackdir  m_res_dest_td;      
  Node      *m_res_node;        
  TileIndex m_res_fail_tile;    
  Trackdir  m_res_fail_td;      
  TileIndex m_origin_tile;      
 
  std::vector<std::pair<TileIndex, Trackdir>> m_signals_set_to_red; 
 
  bool FindSafePositionProc(TileIndex tile, Trackdir td)
  {
    if (IsSafeWaitingPosition(Yapf().GetVehicle(), tile, td, true, !TrackFollower::Allow90degTurns())) {
      m_res_dest = tile;
      m_res_dest_td = td;
      return false;   // Stop iterating segment
    }
    return true;
  }
 
  bool ReserveRailStationPlatform(TileIndex &tile, DiagDirection dir)
  {
    TileIndex     start = tile;
    TileIndexDiff diff = TileOffsByDiagDir(dir);
 
    do {
      if (HasStationReservation(tile)) return false;
      SetRailStationReservation(tile, true);
      MarkTileDirtyByTile(tile);
      tile = TileAdd(tile, diff);
    } while (IsCompatibleTrainStationTile(tile, start) && tile != m_origin_tile);
 
    TriggerStationRandomisation(nullptr, start, SRT_PATH_RESERVATION);
 
    return true;
  }
 
  bool ReserveSingleTrack(TileIndex tile, Trackdir td)
  {
    Trackdir rev_td = ReverseTrackdir(td);
    if (IsRailStationTile(tile)) {
      if (!ReserveRailStationPlatform(tile, TrackdirToExitdir(rev_td))) {
        /* Platform could not be reserved, undo. */
        m_res_fail_tile = tile;
        m_res_fail_td = td;
      }
    } else {
      if (!TryReserveRailTrack(tile, TrackdirToTrack(td))) {
        /* Tile couldn't be reserved, undo. */
        m_res_fail_tile = tile;
        m_res_fail_td = td;
        return false;
      }
 
      /* Green path signal opposing the path? Turn to red. */
      if (HasPbsSignalOnTrackdir(tile, rev_td) && GetSignalStateByTrackdir(tile, rev_td) == SIGNAL_STATE_GREEN) {
        m_signals_set_to_red.emplace_back(tile, rev_td);
        SetSignalStateByTrackdir(tile, rev_td, SIGNAL_STATE_RED);
        MarkTileDirtyByTile(tile);
      }
    }
 
    return tile != m_res_dest || td != m_res_dest_td;
  }
 
  bool UnreserveSingleTrack(TileIndex tile, Trackdir td)
  {
    if (IsRailStationTile(tile)) {
      TileIndex     start = tile;
      TileIndexDiff diff = TileOffsByDiagDir(TrackdirToExitdir(ReverseTrackdir(td)));
      while ((tile != m_res_fail_tile || td != m_res_fail_td) && IsCompatibleTrainStationTile(tile, start)) {
        SetRailStationReservation(tile, false);
        tile = TileAdd(tile, diff);
      }
    } else if (tile != m_res_fail_tile || td != m_res_fail_td) {
      UnreserveRailTrack(tile, TrackdirToTrack(td));
    }
    return (tile != m_res_dest || td != m_res_dest_td) && (tile != m_res_fail_tile || td != m_res_fail_td);
  }
 
public:
  inline void SetReservationTarget(Node *node, TileIndex tile, Trackdir td)
  {
    m_res_node = node;
    m_res_dest = tile;
    m_res_dest_td = td;
  }
 
  inline void FindSafePositionOnNode(Node *node)
  {
    assert(node->m_parent != nullptr);
 
    /* We will never pass more than two signals, no need to check for a safe tile. */
    if (node->m_parent->m_num_signals_passed >= 2) return;
 
    if (!node->IterateTiles(Yapf().GetVehicle(), Yapf(), *this, &CYapfReserveTrack<Types>::FindSafePositionProc)) {
      m_res_node = node;
    }
  }
 
  bool TryReservePath(PBSTileInfo *target, TileIndex origin)
  {
    m_res_fail_tile = INVALID_TILE;
    m_origin_tile = origin;
 
    if (target != nullptr) {
      target->tile = m_res_dest;
      target->trackdir = m_res_dest_td;
      target->okay = false;
    }
 
    /* Don't bother if the target is reserved. */
    if (!IsWaitingPositionFree(Yapf().GetVehicle(), m_res_dest, m_res_dest_td)) return false;
 
    m_signals_set_to_red.clear();
    for (Node *node = m_res_node; node->m_parent != nullptr; node = node->m_parent) {
      node->IterateTiles(Yapf().GetVehicle(), Yapf(), *this, &CYapfReserveTrack<Types>::ReserveSingleTrack);
      if (m_res_fail_tile != INVALID_TILE) {
        /* Reservation failed, undo. */
        Node *fail_node = m_res_node;
        TileIndex stop_tile = m_res_fail_tile;
        do {
          /* If this is the node that failed, stop at the failed tile. */
          m_res_fail_tile = fail_node == node ? stop_tile : INVALID_TILE;
          fail_node->IterateTiles(Yapf().GetVehicle(), Yapf(), *this, &CYapfReserveTrack<Types>::UnreserveSingleTrack);
        } while (fail_node != node && (fail_node = fail_node->m_parent) != nullptr);
 
        /* Re-instate green path signals we turned to red. */
        for (auto [sig_tile, td] : m_signals_set_to_red) {
          SetSignalStateByTrackdir(sig_tile, td, SIGNAL_STATE_GREEN);
        }
 
        return false;
      }
    }
 
    if (target != nullptr) target->okay = true;
 
    if (Yapf().CanUseGlobalCache(*m_res_node)) {
      YapfNotifyTrackLayoutChange(INVALID_TILE, INVALID_TRACK);
    }
 
    return true;
  }
};
 
template <class Types>
class CYapfFollowAnyDepotRailT
{
public:
  typedef typename Types::Tpf Tpf;                     
  typedef typename Types::TrackFollower TrackFollower;
  typedef typename Types::NodeList::Titem Node;        
  typedef typename Node::Key Key;                      
 
protected:
  inline Tpf &Yapf()
  {
    return *static_cast<Tpf *>(this);
  }
 
public:
  inline void PfFollowNode(Node &old_node)
  {
    TrackFollower F(Yapf().GetVehicle());
    if (F.Follow(old_node.GetLastTile(), old_node.GetLastTrackdir())) {
      Yapf().AddMultipleNodes(&old_node, F);
    }
  }
 
  inline char TransportTypeChar() const
  {
    return 't';
  }
 
  static FindDepotData stFindNearestDepotTwoWay(const Train *v, TileIndex t1, Trackdir td1, TileIndex t2, Trackdir td2, int max_penalty, int reverse_penalty)
  {
    Tpf pf1;
    /*
     * With caching enabled it simply cannot get a reliable result when you
     * have limited the distance a train may travel. This means that the
     * cached result does not match uncached result in all cases and that
     * causes desyncs. So disable caching when finding for a depot that is
     * nearby. This only happens with automatic servicing of vehicles,
     * so it will only impact performance when you do not manually set
     * depot orders and you do not disable automatic servicing.
     */
    if (max_penalty != 0) pf1.DisableCache(true);
    FindDepotData result1 = pf1.FindNearestDepotTwoWay(v, t1, td1, t2, td2, max_penalty, reverse_penalty);
 
    if (_debug_desync_level >= 2) {
      Tpf pf2;
      pf2.DisableCache(true);
      FindDepotData result2 = pf2.FindNearestDepotTwoWay(v, t1, td1, t2, td2, max_penalty, reverse_penalty);
      if (result1.tile != result2.tile || (result1.reverse != result2.reverse)) {
        Debug(desync, 2, "warning: FindNearestDepotTwoWay cache mismatch: {} vs {}",
            result1.tile != INVALID_TILE ? "T" : "F",
            result2.tile != INVALID_TILE ? "T" : "F");
        DumpState(pf1, pf2);
      }
    }
 
    return result1;
  }
 
  inline FindDepotData FindNearestDepotTwoWay(const Train *v, TileIndex t1, Trackdir td1, TileIndex t2, Trackdir td2, int max_penalty, int reverse_penalty)
  {
    /* set origin and destination nodes */
    Yapf().SetOrigin(t1, td1, t2, td2, reverse_penalty, true);
    Yapf().SetDestination(v);
    Yapf().SetMaxCost(max_penalty);
 
    /* find the best path */
    if (!Yapf().FindPath(v)) return FindDepotData();
 
    /* Some path found. */
    Node *n = Yapf().GetBestNode();
 
    /* walk through the path back to the origin */
    Node *pNode = n;
    while (pNode->m_parent != nullptr) {
      pNode = pNode->m_parent;
    }
 
    /* if the origin node is our front vehicle tile/Trackdir then we didn't reverse
     * but we can also look at the cost (== 0 -> not reversed, == reverse_penalty -> reversed) */
    return FindDepotData(n->GetLastTile(), n->m_cost, pNode->m_cost != 0);
  }
};
 
template <class Types>
class CYapfFollowAnySafeTileRailT : public CYapfReserveTrack<Types>
{
public:
  typedef typename Types::Tpf Tpf;                     
  typedef typename Types::TrackFollower TrackFollower;
  typedef typename Types::NodeList::Titem Node;        
  typedef typename Node::Key Key;                      
 
protected:
  inline Tpf &Yapf()
  {
    return *static_cast<Tpf *>(this);
  }
 
public:
  inline void PfFollowNode(Node &old_node)
  {
    TrackFollower F(Yapf().GetVehicle(), Yapf().GetCompatibleRailTypes());
    if (F.Follow(old_node.GetLastTile(), old_node.GetLastTrackdir()) && F.MaskReservedTracks()) {
      Yapf().AddMultipleNodes(&old_node, F);
    }
  }
 
  inline char TransportTypeChar() const
  {
    return 't';
  }
 
  static bool stFindNearestSafeTile(const Train *v, TileIndex t1, Trackdir td, bool override_railtype)
  {
    /* Create pathfinder instance */
    Tpf pf1;
    bool result1;
    if (_debug_desync_level < 2) {
      result1 = pf1.FindNearestSafeTile(v, t1, td, override_railtype, false);
    } else {
      bool result2 = pf1.FindNearestSafeTile(v, t1, td, override_railtype, true);
      Tpf pf2;
      pf2.DisableCache(true);
      result1 = pf2.FindNearestSafeTile(v, t1, td, override_railtype, false);
      if (result1 != result2) {
        Debug(desync, 2, "warning: FindSafeTile cache mismatch: {} vs {}", result2 ? "T" : "F", result1 ? "T" : "F");
        DumpState(pf1, pf2);
      }
    }
 
    return result1;
  }
 
  bool FindNearestSafeTile(const Train *v, TileIndex t1, Trackdir td, bool override_railtype, bool dont_reserve)
  {
    /* Set origin and destination. */
    Yapf().SetOrigin(t1, td);
    Yapf().SetDestination(v, override_railtype);
 
    bool bFound = Yapf().FindPath(v);
    if (!bFound) return false;
 
    /* Found a destination, set as reservation target. */
    Node *pNode = Yapf().GetBestNode();
    this->SetReservationTarget(pNode, pNode->GetLastTile(), pNode->GetLastTrackdir());
 
    /* Walk through the path back to the origin. */
    Node *pPrev = nullptr;
    while (pNode->m_parent != nullptr) {
      pPrev = pNode;
      pNode = pNode->m_parent;
 
      this->FindSafePositionOnNode(pPrev);
    }
 
    return dont_reserve || this->TryReservePath(nullptr, pNode->GetLastTile());
  }
};
 
template <class Types>
class CYapfFollowRailT : public CYapfReserveTrack<Types>
{
public:
  typedef typename Types::Tpf Tpf;                     
  typedef typename Types::TrackFollower TrackFollower;
  typedef typename Types::NodeList::Titem Node;        
  typedef typename Node::Key Key;                      
 
protected:
  inline Tpf &Yapf()
  {
    return *static_cast<Tpf *>(this);
  }
 
public:
  inline void PfFollowNode(Node &old_node)
  {
    TrackFollower F(Yapf().GetVehicle());
    if (F.Follow(old_node.GetLastTile(), old_node.GetLastTrackdir())) {
      Yapf().AddMultipleNodes(&old_node, F);
    }
  }
 
  inline char TransportTypeChar() const
  {
    return 't';
  }
 
  static Trackdir stChooseRailTrack(const Train *v, TileIndex tile, DiagDirection enterdir, TrackBits tracks, bool &path_found, bool reserve_track, PBSTileInfo *target, TileIndex *dest)
  {
    /* create pathfinder instance */
    Tpf pf1;
    Trackdir result1;
 
    if (_debug_desync_level < 2) {
      result1 = pf1.ChooseRailTrack(v, tile, enterdir, tracks, path_found, reserve_track, target, dest);
    } else {
      result1 = pf1.ChooseRailTrack(v, tile, enterdir, tracks, path_found, false, nullptr, nullptr);
      Tpf pf2;
      pf2.DisableCache(true);
      Trackdir result2 = pf2.ChooseRailTrack(v, tile, enterdir, tracks, path_found, reserve_track, target, dest);
      if (result1 != result2) {
        Debug(desync, 2, "warning: ChooseRailTrack cache mismatch: {} vs {}", result1, result2);
        DumpState(pf1, pf2);
      }
    }
 
    return result1;
  }
 
  inline Trackdir ChooseRailTrack(const Train *v, TileIndex, DiagDirection, TrackBits, bool &path_found, bool reserve_track, PBSTileInfo *target, TileIndex *dest)
  {
    if (target != nullptr) target->tile = INVALID_TILE;
    if (dest != nullptr) *dest = INVALID_TILE;
 
    /* set origin and destination nodes */
    PBSTileInfo origin = FollowTrainReservation(v);
    Yapf().SetOrigin(origin.tile, origin.trackdir, INVALID_TILE, INVALID_TRACKDIR, 1, true);
    Yapf().SetDestination(v);
 
    /* find the best path */
    path_found = Yapf().FindPath(v);
 
    /* if path not found - return INVALID_TRACKDIR */
    Trackdir next_trackdir = INVALID_TRACKDIR;
    Node *pNode = Yapf().GetBestNode();
    if (pNode != nullptr) {
      /* reserve till end of path */
      this->SetReservationTarget(pNode, pNode->GetLastTile(), pNode->GetLastTrackdir());
 
      /* path was found or at least suggested
       * walk through the path back to the origin */
      Node *pPrev = nullptr;
      while (pNode->m_parent != nullptr) {
        pPrev = pNode;
        pNode = pNode->m_parent;
 
        this->FindSafePositionOnNode(pPrev);
      }
 
      /* If the best PF node has no parent, then there is no (valid) best next trackdir to return.
       * This occurs when the PF is called while the train is already at its destination. */
      if (pPrev == nullptr) return INVALID_TRACKDIR;
 
      /* return trackdir from the best origin node (one of start nodes) */
      Node &best_next_node = *pPrev;
      next_trackdir = best_next_node.GetTrackdir();
 
      if (reserve_track && path_found) {
        if (dest != nullptr) *dest = Yapf().GetBestNode()->GetLastTile();
        this->TryReservePath(target, pNode->GetLastTile());
      }
    }
 
    /* Treat the path as found if stopped on the first two way signal(s). */
    path_found |= Yapf().m_stopped_on_first_two_way_signal;
    return next_trackdir;
  }
 
  static bool stCheckReverseTrain(const Train *v, TileIndex t1, Trackdir td1, TileIndex t2, Trackdir td2, int reverse_penalty)
  {
    Tpf pf1;
    bool result1 = pf1.CheckReverseTrain(v, t1, td1, t2, td2, reverse_penalty);
 
    if (_debug_desync_level >= 2) {
      Tpf pf2;
      pf2.DisableCache(true);
      bool result2 = pf2.CheckReverseTrain(v, t1, td1, t2, td2, reverse_penalty);
      if (result1 != result2) {
        Debug(desync, 2, "warning: CheckReverseTrain cache mismatch: {} vs {}", result1 ? "T" : "F", result2 ? "T" : "F");
        DumpState(pf1, pf2);
      }
    }
 
    return result1;
  }
 
  inline bool CheckReverseTrain(const Train *v, TileIndex t1, Trackdir td1, TileIndex t2, Trackdir td2, int reverse_penalty)
  {
    /* create pathfinder instance
     * set origin and destination nodes */
    Yapf().SetOrigin(t1, td1, t2, td2, reverse_penalty, false);
    Yapf().SetDestination(v);
 
    /* find the best path */
    bool bFound = Yapf().FindPath(v);
 
    if (!bFound) return false;
 
    /* path was found
     * walk through the path back to the origin */
    Node *pNode = Yapf().GetBestNode();
    while (pNode->m_parent != nullptr) {
      pNode = pNode->m_parent;
    }
 
    /* check if it was reversed origin */
    Node &best_org_node = *pNode;
    bool reversed = (best_org_node.m_cost != 0);
    return reversed;
  }
};
 
template <class Tpf_, class Ttrack_follower, class Tnode_list, template <class Types> class TdestinationT, template <class Types> class TfollowT>
struct CYapfRail_TypesT
{
  typedef CYapfRail_TypesT<Tpf_, Ttrack_follower, Tnode_list, TdestinationT, TfollowT>  Types;
 
  typedef Tpf_                                Tpf;
  typedef Ttrack_follower                     TrackFollower;
  typedef Tnode_list                          NodeList;
  typedef Train                               VehicleType;
  typedef CYapfBaseT<Types>                   PfBase;
  typedef TfollowT<Types>                     PfFollow;
  typedef CYapfOriginTileTwoWayT<Types>       PfOrigin;
  typedef TdestinationT<Types>                PfDestination;
  typedef CYapfSegmentCostCacheGlobalT<Types> PfCache;
  typedef CYapfCostRailT<Types>               PfCost;
};
 
struct CYapfRail1         : CYapfT<CYapfRail_TypesT<CYapfRail1        , CFollowTrackRail    , CRailNodeListTrackDir, CYapfDestinationTileOrStationRailT, CYapfFollowRailT> > {};
struct CYapfRail2         : CYapfT<CYapfRail_TypesT<CYapfRail2        , CFollowTrackRailNo90, CRailNodeListTrackDir, CYapfDestinationTileOrStationRailT, CYapfFollowRailT> > {};
 
struct CYapfAnyDepotRail1 : CYapfT<CYapfRail_TypesT<CYapfAnyDepotRail1, CFollowTrackRail    , CRailNodeListTrackDir, CYapfDestinationAnyDepotRailT     , CYapfFollowAnyDepotRailT> > {};
struct CYapfAnyDepotRail2 : CYapfT<CYapfRail_TypesT<CYapfAnyDepotRail2, CFollowTrackRailNo90, CRailNodeListTrackDir, CYapfDestinationAnyDepotRailT     , CYapfFollowAnyDepotRailT> > {};
 
struct CYapfAnySafeTileRail1 : CYapfT<CYapfRail_TypesT<CYapfAnySafeTileRail1, CFollowTrackFreeRail    , CRailNodeListTrackDir, CYapfDestinationAnySafeTileRailT , CYapfFollowAnySafeTileRailT> > {};
struct CYapfAnySafeTileRail2 : CYapfT<CYapfRail_TypesT<CYapfAnySafeTileRail2, CFollowTrackFreeRailNo90, CRailNodeListTrackDir, CYapfDestinationAnySafeTileRailT , CYapfFollowAnySafeTileRailT> > {};
 
 
Track YapfTrainChooseTrack(const Train *v, TileIndex tile, DiagDirection enterdir, TrackBits tracks, bool &path_found, bool reserve_track, PBSTileInfo *target, TileIndex *dest)
{
  /* default is YAPF type 2 */
  typedef Trackdir (*PfnChooseRailTrack)(const Train*, TileIndex, DiagDirection, TrackBits, bool&, bool, PBSTileInfo*, TileIndex*);
  PfnChooseRailTrack pfnChooseRailTrack = &CYapfRail1::stChooseRailTrack;
 
  /* check if non-default YAPF type needed */
  if (_settings_game.pf.forbid_90_deg) {
    pfnChooseRailTrack = &CYapfRail2::stChooseRailTrack; // Trackdir, forbid 90-deg
  }
 
  Trackdir td_ret = pfnChooseRailTrack(v, tile, enterdir, tracks, path_found, reserve_track, target, dest);
  return (td_ret != INVALID_TRACKDIR) ? TrackdirToTrack(td_ret) : FindFirstTrack(tracks);
}
 
bool YapfTrainCheckReverse(const Train *v)
{
  const Train *last_veh = v->Last();
 
  /* get trackdirs of both ends */
  Trackdir td = v->GetVehicleTrackdir();
  Trackdir td_rev = ReverseTrackdir(last_veh->GetVehicleTrackdir());
 
  /* tiles where front and back are */
  TileIndex tile = v->tile;
  TileIndex tile_rev = last_veh->tile;
 
  int reverse_penalty = 0;
 
  if (v->track == TRACK_BIT_WORMHOLE) {
    /* front in tunnel / on bridge */
    DiagDirection dir_into_wormhole = GetTunnelBridgeDirection(tile);
 
    if (TrackdirToExitdir(td) == dir_into_wormhole) tile = GetOtherTunnelBridgeEnd(tile);
    /* Now 'tile' is the tunnel entry/bridge ramp the train will reach when driving forward */
 
    /* Current position of the train in the wormhole */
    TileIndex cur_tile = TileVirtXY(v->x_pos, v->y_pos);
 
    /* Add distance to drive in the wormhole as penalty for the forward path, i.e. bonus for the reverse path
     * Note: Negative penalties are ok for the start tile. */
    reverse_penalty -= DistanceManhattan(cur_tile, tile) * YAPF_TILE_LENGTH;
  }
 
  if (last_veh->track == TRACK_BIT_WORMHOLE) {
    /* back in tunnel / on bridge */
    DiagDirection dir_into_wormhole = GetTunnelBridgeDirection(tile_rev);
 
    if (TrackdirToExitdir(td_rev) == dir_into_wormhole) tile_rev = GetOtherTunnelBridgeEnd(tile_rev);
    /* Now 'tile_rev' is the tunnel entry/bridge ramp the train will reach when reversing */
 
    /* Current position of the last wagon in the wormhole */
    TileIndex cur_tile = TileVirtXY(last_veh->x_pos, last_veh->y_pos);
 
    /* Add distance to drive in the wormhole as penalty for the revere path. */
    reverse_penalty += DistanceManhattan(cur_tile, tile_rev) * YAPF_TILE_LENGTH;
  }
 
  typedef bool (*PfnCheckReverseTrain)(const Train*, TileIndex, Trackdir, TileIndex, Trackdir, int);
  PfnCheckReverseTrain pfnCheckReverseTrain = CYapfRail1::stCheckReverseTrain;
 
  /* check if non-default YAPF type needed */
  if (_settings_game.pf.forbid_90_deg) {
    pfnCheckReverseTrain = &CYapfRail2::stCheckReverseTrain; // Trackdir, forbid 90-deg
  }
 
  /* slightly hackish: If the pathfinders finds a path, the cost of the first node is tested to distinguish between forward- and reverse-path. */
  if (reverse_penalty == 0) reverse_penalty = 1;
 
  bool reverse = pfnCheckReverseTrain(v, tile, td, tile_rev, td_rev, reverse_penalty);
 
  return reverse;
}
 
FindDepotData YapfTrainFindNearestDepot(const Train *v, int max_penalty)
{
  const Train *last_veh = v->Last();
 
  PBSTileInfo origin = FollowTrainReservation(v);
  TileIndex last_tile = last_veh->tile;
  Trackdir td_rev = ReverseTrackdir(last_veh->GetVehicleTrackdir());
 
  typedef FindDepotData (*PfnFindNearestDepotTwoWay)(const Train*, TileIndex, Trackdir, TileIndex, Trackdir, int, int);
  PfnFindNearestDepotTwoWay pfnFindNearestDepotTwoWay = &CYapfAnyDepotRail1::stFindNearestDepotTwoWay;
 
  /* check if non-default YAPF type needed */
  if (_settings_game.pf.forbid_90_deg) {
    pfnFindNearestDepotTwoWay = &CYapfAnyDepotRail2::stFindNearestDepotTwoWay; // Trackdir, forbid 90-deg
  }
 
  return pfnFindNearestDepotTwoWay(v, origin.tile, origin.trackdir, last_tile, td_rev, max_penalty, YAPF_INFINITE_PENALTY);
}
 
bool YapfTrainFindNearestSafeTile(const Train *v, TileIndex tile, Trackdir td, bool override_railtype)
{
  typedef bool (*PfnFindNearestSafeTile)(const Train*, TileIndex, Trackdir, bool);
  PfnFindNearestSafeTile pfnFindNearestSafeTile = CYapfAnySafeTileRail1::stFindNearestSafeTile;
 
  /* check if non-default YAPF type needed */
  if (_settings_game.pf.forbid_90_deg) {
    pfnFindNearestSafeTile = &CYapfAnySafeTileRail2::stFindNearestSafeTile;
  }
 
  return pfnFindNearestSafeTile(v, tile, td, override_railtype);
}
 
int CSegmentCostCacheBase::s_rail_change_counter = 0;
 
void YapfNotifyTrackLayoutChange(TileIndex tile, Track track)
{
  CSegmentCostCacheBase::NotifyTrackLayoutChange(tile, track);
}