Codechange: Use null pointer literal instead of the NULL macro

[openttd-github.git] / src / pathfinder / follow_track.hpp

/* $Id$ */

/*
 * 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/>.
 */

/** @file follow_track.hpp Template function for track followers */

#ifndef  FOLLOW_TRACK_HPP
#define  FOLLOW_TRACK_HPP

#include "../pbs.h"
#include "../roadveh.h"
#include "../station_base.h"
#include "../train.h"
#include "../tunnelbridge.h"
#include "../tunnelbridge_map.h"
#include "../depot_map.h"
#include "pf_performance_timer.hpp"

/**
 * Track follower helper template class (can serve pathfinders and vehicle
 *  controllers). See 6 different typedefs below for 3 different transport
 *  types w/ or w/o 90-deg turns allowed
 */
template <TransportType Ttr_type_, typename VehicleType, bool T90deg_turns_allowed_ = true, bool Tmask_reserved_tracks = false>
struct CFollowTrackT
{
        enum ErrorCode {
                EC_NONE,
                EC_OWNER,
                EC_RAIL_TYPE,
                EC_90DEG,
                EC_NO_WAY,
                EC_RESERVED,
        };

        const VehicleType  *m_veh;           ///< moving vehicle
        Owner               m_veh_owner;     ///< owner of the vehicle
        TileIndex           m_old_tile;      ///< the origin (vehicle moved from) before move
        Trackdir            m_old_td;        ///< the trackdir (the vehicle was on) before move
        TileIndex           m_new_tile;      ///< the new tile (the vehicle has entered)
        TrackdirBits        m_new_td_bits;   ///< the new set of available trackdirs
        DiagDirection       m_exitdir;       ///< exit direction (leaving the old tile)
        bool                m_is_tunnel;     ///< last turn passed tunnel
        bool                m_is_bridge;     ///< last turn passed bridge ramp
        bool                m_is_station;    ///< last turn passed station
        int                 m_tiles_skipped; ///< number of skipped tunnel or station tiles
        ErrorCode           m_err;
        CPerformanceTimer  *m_pPerf;
        RailTypes           m_railtypes;

        inline CFollowTrackT(const VehicleType *v = nullptr, RailTypes railtype_override = INVALID_RAILTYPES, CPerformanceTimer *pPerf = nullptr)
        {
                Init(v, railtype_override, pPerf);
        }

        inline CFollowTrackT(Owner o, RailTypes railtype_override = INVALID_RAILTYPES, CPerformanceTimer *pPerf = nullptr)
        {
                m_veh = nullptr;
                Init(o, railtype_override, pPerf);
        }

        inline void Init(const VehicleType *v, RailTypes railtype_override, CPerformanceTimer *pPerf)
        {
                assert(!IsRailTT() || (v != nullptr && v->type == VEH_TRAIN));
                m_veh = v;
                Init(v != nullptr ? v->owner : INVALID_OWNER, IsRailTT() && railtype_override == INVALID_RAILTYPES ? Train::From(v)->compatible_railtypes : railtype_override, pPerf);
        }

        inline void Init(Owner o, RailTypes railtype_override, CPerformanceTimer *pPerf)
        {
                assert(!IsRoadTT() || m_veh != nullptr);
                assert(!IsRailTT() || railtype_override != INVALID_RAILTYPES);
                m_veh_owner = o;
                m_pPerf = pPerf;
                /* don't worry, all is inlined so compiler should remove unnecessary initializations */
                m_old_tile = INVALID_TILE;
                m_old_td = INVALID_TRACKDIR;
                m_new_tile = INVALID_TILE;
                m_new_td_bits = TRACKDIR_BIT_NONE;
                m_exitdir = INVALID_DIAGDIR;
                m_is_station = m_is_bridge = m_is_tunnel = false;
                m_tiles_skipped = 0;
                m_err = EC_NONE;
                m_railtypes = railtype_override;
        }

        inline static TransportType TT() { return Ttr_type_; }
        inline static bool IsWaterTT() { return TT() == TRANSPORT_WATER; }
        inline static bool IsRailTT() { return TT() == TRANSPORT_RAIL; }
        inline bool IsTram() { return IsRoadTT() && HasBit(RoadVehicle::From(m_veh)->compatible_roadtypes, ROADTYPE_TRAM); }
        inline static bool IsRoadTT() { return TT() == TRANSPORT_ROAD; }
        inline static bool Allow90degTurns() { return T90deg_turns_allowed_; }
        inline static bool DoTrackMasking() { return Tmask_reserved_tracks; }

        /** Tests if a tile is a road tile with a single tramtrack (tram can reverse) */
        inline DiagDirection GetSingleTramBit(TileIndex tile)
        {
                assert(IsTram()); // this function shouldn't be called in other cases

                if (IsNormalRoadTile(tile)) {
                        RoadBits rb = GetRoadBits(tile, ROADTYPE_TRAM);
                        switch (rb) {
                                case ROAD_NW: return DIAGDIR_NW;
                                case ROAD_SW: return DIAGDIR_SW;
                                case ROAD_SE: return DIAGDIR_SE;
                                case ROAD_NE: return DIAGDIR_NE;
                                default: break;
                        }
                }
                return INVALID_DIAGDIR;
        }

        /**
         * main follower routine. Fills all members and return true on success.
         *  Otherwise returns false if track can't be followed.
         */
        inline bool Follow(TileIndex old_tile, Trackdir old_td)
        {
                m_old_tile = old_tile;
                m_old_td = old_td;
                m_err = EC_NONE;
                assert(
                        ((TrackStatusToTrackdirBits(
                                GetTileTrackStatus(m_old_tile, TT(), (IsRoadTT() && m_veh != nullptr) ? RoadVehicle::From(m_veh)->compatible_roadtypes : 0)
                        ) & TrackdirToTrackdirBits(m_old_td)) != 0) ||
                        (IsTram() && GetSingleTramBit(m_old_tile) != INVALID_DIAGDIR) // Disable the assertion for single tram bits
                );
                m_exitdir = TrackdirToExitdir(m_old_td);
                if (ForcedReverse()) return true;
                if (!CanExitOldTile()) return false;
                FollowTileExit();
                if (!QueryNewTileTrackStatus()) return TryReverse();
                m_new_td_bits &= DiagdirReachesTrackdirs(m_exitdir);
                if (m_new_td_bits == TRACKDIR_BIT_NONE || !CanEnterNewTile()) {
                        /* In case we can't enter the next tile, but are
                         * a normal road vehicle, then we can actually
                         * try to reverse as this is the end of the road.
                         * Trams can only turn on the appropriate bits in
                         * which case reaching this would mean a dead end
                         * near a building and in that case there would
                         * a "false" QueryNewTileTrackStatus result and
                         * as such reversing is already tried. The fact
                         * that function failed can have to do with a
                         * missing road bit, or inability to connect the
                         * different bits due to slopes. */
                        if (IsRoadTT() && !IsTram() && TryReverse()) return true;

                        /* CanEnterNewTile already set a reason.
                         * Do NOT overwrite it (important for example for EC_RAIL_TYPE).
                         * Only set a reason if CanEnterNewTile was not called */
                        if (m_new_td_bits == TRACKDIR_BIT_NONE) m_err = EC_NO_WAY;

                        return false;
                }
                if ((!IsRailTT() && !Allow90degTurns()) || (IsRailTT() && Rail90DegTurnDisallowed(GetTileRailType(m_old_tile), GetTileRailType(m_new_tile), !Allow90degTurns()))) {
                        m_new_td_bits &= (TrackdirBits)~(int)TrackdirCrossesTrackdirs(m_old_td);
                        if (m_new_td_bits == TRACKDIR_BIT_NONE) {
                                m_err = EC_90DEG;
                                return false;
                        }
                }
                return true;
        }

        inline bool MaskReservedTracks()
        {
                if (!DoTrackMasking()) return true;

                if (m_is_station) {
                        /* Check skipped station tiles as well. */
                        TileIndexDiff diff = TileOffsByDiagDir(m_exitdir);
                        for (TileIndex tile = m_new_tile - diff * m_tiles_skipped; tile != m_new_tile; tile += diff) {
                                if (HasStationReservation(tile)) {
                                        m_new_td_bits = TRACKDIR_BIT_NONE;
                                        m_err = EC_RESERVED;
                                        return false;
                                }
                        }
                }

                TrackBits reserved = GetReservedTrackbits(m_new_tile);
                /* Mask already reserved trackdirs. */
                m_new_td_bits &= ~TrackBitsToTrackdirBits(reserved);
                /* Mask out all trackdirs that conflict with the reservation. */
                Track t;
                FOR_EACH_SET_TRACK(t, TrackdirBitsToTrackBits(m_new_td_bits)) {
                        if (TracksOverlap(reserved | TrackToTrackBits(t))) m_new_td_bits &= ~TrackToTrackdirBits(t);
                }
                if (m_new_td_bits == TRACKDIR_BIT_NONE) {
                        m_err = EC_RESERVED;
                        return false;
                }
                return true;
        }

protected:
        /** Follow the m_exitdir from m_old_tile and fill m_new_tile and m_tiles_skipped */
        inline void FollowTileExit()
        {
                m_is_station = m_is_bridge = m_is_tunnel = false;
                m_tiles_skipped = 0;

                /* extra handling for tunnels and bridges in our direction */
                if (IsTileType(m_old_tile, MP_TUNNELBRIDGE)) {
                        DiagDirection enterdir = GetTunnelBridgeDirection(m_old_tile);
                        if (enterdir == m_exitdir) {
                                /* we are entering the tunnel / bridge */
                                if (IsTunnel(m_old_tile)) {
                                        m_is_tunnel = true;
                                        m_new_tile = GetOtherTunnelEnd(m_old_tile);
                                } else { // IsBridge(m_old_tile)
                                        m_is_bridge = true;
                                        m_new_tile = GetOtherBridgeEnd(m_old_tile);
                                }
                                m_tiles_skipped = GetTunnelBridgeLength(m_new_tile, m_old_tile);
                                return;
                        }
                        assert(ReverseDiagDir(enterdir) == m_exitdir);
                }

                /* normal or station tile, do one step */
                m_new_tile = TileAddByDiagDir(m_old_tile, m_exitdir);

                /* special handling for stations */
                if (IsRailTT() && HasStationTileRail(m_new_tile)) {
                        m_is_station = true;
                } else if (IsRoadTT() && IsRoadStopTile(m_new_tile)) {
                        m_is_station = true;
                }
        }

        /** stores track status (available trackdirs) for the new tile into m_new_td_bits */
        inline bool QueryNewTileTrackStatus()
        {
                CPerfStart perf(*m_pPerf);
                if (IsRailTT() && IsPlainRailTile(m_new_tile)) {
                        m_new_td_bits = (TrackdirBits)(GetTrackBits(m_new_tile) * 0x101);
                } else {
                        m_new_td_bits = TrackStatusToTrackdirBits(GetTileTrackStatus(m_new_tile, TT(), IsRoadTT() ? RoadVehicle::From(m_veh)->compatible_roadtypes : 0));

                        if (IsTram() && m_new_td_bits == TRACKDIR_BIT_NONE) {
                                /* GetTileTrackStatus() returns 0 for single tram bits.
                                 * As we cannot change it there (easily) without breaking something, change it here */
                                switch (GetSingleTramBit(m_new_tile)) {
                                        case DIAGDIR_NE:
                                        case DIAGDIR_SW:
                                                m_new_td_bits = TRACKDIR_BIT_X_NE | TRACKDIR_BIT_X_SW;
                                                break;

                                        case DIAGDIR_NW:
                                        case DIAGDIR_SE:
                                                m_new_td_bits = TRACKDIR_BIT_Y_NW | TRACKDIR_BIT_Y_SE;
                                                break;

                                        default: break;
                                }
                        }
                }
                return (m_new_td_bits != TRACKDIR_BIT_NONE);
        }

        /** return true if we can leave m_old_tile in m_exitdir */
        inline bool CanExitOldTile()
        {
                /* road stop can be left at one direction only unless it's a drive-through stop */
                if (IsRoadTT() && IsStandardRoadStopTile(m_old_tile)) {
                        DiagDirection exitdir = GetRoadStopDir(m_old_tile);
                        if (exitdir != m_exitdir) {
                                m_err = EC_NO_WAY;
                                return false;
                        }
                }

                /* single tram bits can only be left in one direction */
                if (IsTram()) {
                        DiagDirection single_tram = GetSingleTramBit(m_old_tile);
                        if (single_tram != INVALID_DIAGDIR && single_tram != m_exitdir) {
                                m_err = EC_NO_WAY;
                                return false;
                        }
                }

                /* road depots can be also left in one direction only */
                if (IsRoadTT() && IsDepotTypeTile(m_old_tile, TT())) {
                        DiagDirection exitdir = GetRoadDepotDirection(m_old_tile);
                        if (exitdir != m_exitdir) {
                                m_err = EC_NO_WAY;
                                return false;
                        }
                }
                return true;
        }

        /** return true if we can enter m_new_tile from m_exitdir */
        inline bool CanEnterNewTile()
        {
                if (IsRoadTT() && IsStandardRoadStopTile(m_new_tile)) {
                        /* road stop can be entered from one direction only unless it's a drive-through stop */
                        DiagDirection exitdir = GetRoadStopDir(m_new_tile);
                        if (ReverseDiagDir(exitdir) != m_exitdir) {
                                m_err = EC_NO_WAY;
                                return false;
                        }
                }

                /* single tram bits can only be entered from one direction */
                if (IsTram()) {
                        DiagDirection single_tram = GetSingleTramBit(m_new_tile);
                        if (single_tram != INVALID_DIAGDIR && single_tram != ReverseDiagDir(m_exitdir)) {
                                m_err = EC_NO_WAY;
                                return false;
                        }
                }

                /* road and rail depots can also be entered from one direction only */
                if (IsRoadTT() && IsDepotTypeTile(m_new_tile, TT())) {
                        DiagDirection exitdir = GetRoadDepotDirection(m_new_tile);
                        if (ReverseDiagDir(exitdir) != m_exitdir) {
                                m_err = EC_NO_WAY;
                                return false;
                        }
                        /* don't try to enter other company's depots */
                        if (GetTileOwner(m_new_tile) != m_veh_owner) {
                                m_err = EC_OWNER;
                                return false;
                        }
                }
                if (IsRailTT() && IsDepotTypeTile(m_new_tile, TT())) {
                        DiagDirection exitdir = GetRailDepotDirection(m_new_tile);
                        if (ReverseDiagDir(exitdir) != m_exitdir) {
                                m_err = EC_NO_WAY;
                                return false;
                        }
                }

                /* rail transport is possible only on tiles with the same owner as vehicle */
                if (IsRailTT() && GetTileOwner(m_new_tile) != m_veh_owner) {
                        /* different owner */
                        m_err = EC_NO_WAY;
                        return false;
                }

                /* rail transport is possible only on compatible rail types */
                if (IsRailTT()) {
                        RailType rail_type = GetTileRailType(m_new_tile);
                        if (!HasBit(m_railtypes, rail_type)) {
                                /* incompatible rail type */
                                m_err = EC_RAIL_TYPE;
                                return false;
                        }
                }

                /* tunnel holes and bridge ramps can be entered only from proper direction */
                if (IsTileType(m_new_tile, MP_TUNNELBRIDGE)) {
                        if (IsTunnel(m_new_tile)) {
                                if (!m_is_tunnel) {
                                        DiagDirection tunnel_enterdir = GetTunnelBridgeDirection(m_new_tile);
                                        if (tunnel_enterdir != m_exitdir) {
                                                m_err = EC_NO_WAY;
                                                return false;
                                        }
                                }
                        } else { // IsBridge(m_new_tile)
                                if (!m_is_bridge) {
                                        DiagDirection ramp_enderdir = GetTunnelBridgeDirection(m_new_tile);
                                        if (ramp_enderdir != m_exitdir) {
                                                m_err = EC_NO_WAY;
                                                return false;
                                        }
                                }
                        }
                }

                /* special handling for rail stations - get to the end of platform */
                if (IsRailTT() && m_is_station) {
                        /* entered railway station
                         * get platform length */
                        uint length = BaseStation::GetByTile(m_new_tile)->GetPlatformLength(m_new_tile, TrackdirToExitdir(m_old_td));
                        /* how big step we must do to get to the last platform tile; */
                        m_tiles_skipped = length - 1;
                        /* move to the platform end */
                        TileIndexDiff diff = TileOffsByDiagDir(m_exitdir);
                        diff *= m_tiles_skipped;
                        m_new_tile = TILE_ADD(m_new_tile, diff);
                        return true;
                }

                return true;
        }

        /** return true if we must reverse (in depots and single tram bits) */
        inline bool ForcedReverse()
        {
                /* rail and road depots cause reversing */
                if (!IsWaterTT() && IsDepotTypeTile(m_old_tile, TT())) {
                        DiagDirection exitdir = IsRailTT() ? GetRailDepotDirection(m_old_tile) : GetRoadDepotDirection(m_old_tile);
                        if (exitdir != m_exitdir) {
                                /* reverse */
                                m_new_tile = m_old_tile;
                                m_new_td_bits = TrackdirToTrackdirBits(ReverseTrackdir(m_old_td));
                                m_exitdir = exitdir;
                                m_tiles_skipped = 0;
                                m_is_tunnel = m_is_bridge = m_is_station = false;
                                return true;
                        }
                }

                /* Single tram bits and standard road stops cause reversing. */
                if (IsRoadTT() && ((IsTram() && GetSingleTramBit(m_old_tile) == ReverseDiagDir(m_exitdir)) ||
                                (IsStandardRoadStopTile(m_old_tile) && GetRoadStopDir(m_old_tile) == ReverseDiagDir(m_exitdir)))) {
                        /* reverse */
                        m_new_tile = m_old_tile;
                        m_new_td_bits = TrackdirToTrackdirBits(ReverseTrackdir(m_old_td));
                        m_exitdir = ReverseDiagDir(m_exitdir);
                        m_tiles_skipped = 0;
                        m_is_tunnel = m_is_bridge = m_is_station = false;
                        return true;
                }

                return false;
        }

        /** return true if we successfully reversed at end of road/track */
        inline bool TryReverse()
        {
                if (IsRoadTT() && !IsTram()) {
                        /* if we reached the end of road, we can reverse the RV and continue moving */
                        m_exitdir = ReverseDiagDir(m_exitdir);
                        /* new tile will be the same as old one */
                        m_new_tile = m_old_tile;
                        /* set new trackdir bits to all reachable trackdirs */
                        QueryNewTileTrackStatus();
                        m_new_td_bits &= DiagdirReachesTrackdirs(m_exitdir);
                        if (m_new_td_bits != TRACKDIR_BIT_NONE) {
                                /* we have some trackdirs reachable after reversal */
                                return true;
                        }
                }
                m_err = EC_NO_WAY;
                return false;
        }

public:
        /** Helper for pathfinders - get min/max speed on the m_old_tile/m_old_td */
        int GetSpeedLimit(int *pmin_speed = nullptr) const
        {
                int min_speed = 0;
                int max_speed = INT_MAX; // no limit

                /* Check for on-bridge speed limit */
                if (!IsWaterTT() && IsBridgeTile(m_old_tile)) {
                        int spd = GetBridgeSpec(GetBridgeType(m_old_tile))->speed;
                        if (IsRoadTT()) spd *= 2;
                        if (max_speed > spd) max_speed = spd;
                }
                /* Check for speed limit imposed by railtype */
                if (IsRailTT()) {
                        uint16 rail_speed = GetRailTypeInfo(GetRailType(m_old_tile))->max_speed;
                        if (rail_speed > 0) max_speed = min(max_speed, rail_speed);
                }

                /* if min speed was requested, return it */
                if (pmin_speed != nullptr) *pmin_speed = min_speed;
                return max_speed;
        }
};

typedef CFollowTrackT<TRANSPORT_WATER, Ship,        true > CFollowTrackWater;
typedef CFollowTrackT<TRANSPORT_ROAD,  RoadVehicle, true > CFollowTrackRoad;
typedef CFollowTrackT<TRANSPORT_RAIL,  Train,       true > CFollowTrackRail;

typedef CFollowTrackT<TRANSPORT_RAIL,  Train,       false> CFollowTrackRailNo90;

typedef CFollowTrackT<TRANSPORT_RAIL, Train, true,  true > CFollowTrackFreeRail;
typedef CFollowTrackT<TRANSPORT_RAIL, Train, false, true > CFollowTrackFreeRailNo90;

#endif /* FOLLOW_TRACK_HPP */