Tracerestrict: Add slot action mode, try to acquire (only on reserve)

src/lang/english.txt

@@ -3010,6 +3010,7 @@ STR_TRACE_RESTRICT_COUNTER_OP                                   :Counter operati
 STR_TRACE_RESTRICT_PF_PENALTY_CONTROL                           :Penalty config
 STR_TRACE_RESTRICT_SLOT_ACQUIRE_WAIT                            :Acquire or wait
 STR_TRACE_RESTRICT_SLOT_TRY_ACQUIRE                             :Try to acquire
+STR_TRACE_RESTRICT_SLOT_TRY_ACQUIRE_ON_RES                      :Try to acquire (on reserve)
 STR_TRACE_RESTRICT_SLOT_RELEASE_FRONT                           :Release (front)
 STR_TRACE_RESTRICT_SLOT_RELEASE_BACK                            :Release (back)
 STR_TRACE_RESTRICT_SLOT_PBS_RES_END_ACQUIRE_WAIT                :PBS end: Acquire or wait
@@ -3017,6 +3018,7 @@ STR_TRACE_RESTRICT_SLOT_PBS_RES_END_TRY_ACQUIRE                 :PBS end: Try to
 STR_TRACE_RESTRICT_SLOT_PBS_RES_END_RELEASE                     :PBS end: Release
 STR_TRACE_RESTRICT_SLOT_ACQUIRE_WAIT_ITEM                       :Acquire slot: {STRING1}{BLACK}{STRING}, or wait at PBS signal
 STR_TRACE_RESTRICT_SLOT_TRY_ACQUIRE_ITEM                        :Try to acquire slot: {STRING1}{BLACK}{STRING}, or continue anyway
+STR_TRACE_RESTRICT_SLOT_TRY_ACQUIRE_ITEM_RES_ONLY               :Try to acquire (on PBS reserve) slot: {STRING1}{BLACK}{STRING}, or continue anyway
 STR_TRACE_RESTRICT_SLOT_RELEASE_FRONT_ITEM                      :Release slot: {STRING1}{BLACK}{STRING} (front of train)
 STR_TRACE_RESTRICT_SLOT_RELEASE_BACK_ITEM                       :Release slot: {STRING1}{BLACK}{STRING} (back of train)
 STR_TRACE_RESTRICT_SLOT_PBS_RES_END_ACQUIRE_WAIT_ITEM           :PBS reservation ending here: Acquire slot: {STRING1}{BLACK}{STRING}, or wait at start

src/saveload/extended_ver_sl.cpp

@@ -68,7 +68,7 @@ static uint32 saveLC(const SlxiSubChunkInfo *info, bool dry_run);
 
 const SlxiSubChunkInfo _sl_xv_sub_chunk_infos[] = {
 	{ XSLFI_VERSION_LABEL,          XSCF_IGNORABLE_ALL,       1,   1, "version_label",             saveVL,  loadVL,  nullptr        },
-	{ XSLFI_TRACE_RESTRICT,         XSCF_NULL,               11,  11, "tracerestrict",             nullptr, nullptr, "TRRM,TRRP,TRRS" },
+	{ XSLFI_TRACE_RESTRICT,         XSCF_NULL,               12,  12, "tracerestrict",             nullptr, nullptr, "TRRM,TRRP,TRRS" },
 	{ XSLFI_TRACE_RESTRICT_OWNER,   XSCF_NULL,                1,   1, "tracerestrict_owner",       nullptr, nullptr, nullptr        },
 	{ XSLFI_TRACE_RESTRICT_ORDRCND, XSCF_NULL,                3,   3, "tracerestrict_order_cond",  nullptr, nullptr, nullptr        },
 	{ XSLFI_TRACE_RESTRICT_STATUSCND,XSCF_NULL,               1,   1, "tracerestrict_status_cond", nullptr, nullptr, nullptr        },

src/tracerestrict.cpp

@@ -671,6 +671,10 @@ void TraceRestrictProgram::Execute(const Train* v, const TraceRestrictProgramInp
 								if (input.permitted_slot_operations & TRPISP_PBS_RES_END_RELEASE) slot->Vacate(v->index);
 								break;
 
+							case TRSCOF_ACQUIRE_TRY_ON_RESERVE:
+								if (input.permitted_slot_operations & TRPISP_ACQUIRE_ON_RES) slot->Occupy(v->index);
+								break;
+
 							default:
 								NOT_REACHED();
 								break;
@@ -924,6 +928,10 @@ CommandCost TraceRestrictProgram::Validate(const std::vector<TraceRestrictItem>
 							actions_used_flags |= TRPAUF_PBS_RES_END_SLOT;
 							break;
 
+						case TRSCOF_ACQUIRE_TRY_ON_RESERVE:
+							actions_used_flags |= TRPAUF_SLOT_ACQUIRE_ON_RES;
+							break;
+
 						default:
 							NOT_REACHED();
 							break;

src/tracerestrict.h

@@ -327,6 +327,7 @@ enum TraceRestrictSlotCondOpField {
 	TRSCOF_PBS_RES_END_ACQ_WAIT   = 4,       ///< PBS reservations ending at this signal: acquire a slot, or wait
 	TRSCOF_PBS_RES_END_ACQ_TRY    = 5,       ///< PBS reservations ending at this signal: acquire a slot, or carry on otherwise
 	TRSCOF_PBS_RES_END_RELEASE    = 6,       ///< PBS reservations ending at this signal: release a slot
+	TRSCOF_ACQUIRE_TRY_ON_RESERVE = 7,       ///< try to acquire a slot (on reserve), or carry on otherwise
 	/* space up to 8 */
 };
 
@@ -403,6 +404,7 @@ enum TraceRestrictProgramActionsUsedFlags {
 	TRPAUF_TRAIN_NOT_STUCK        = 1 << 11, ///< Train is not stuck
 	TRPAUF_CHANGE_COUNTER         = 1 << 12, ///< Change counter value is present
 	TRPAUF_NO_PBS_BACK_PENALTY    = 1 << 13, ///< No PBS back penalty is present
+	TRPAUF_SLOT_ACQUIRE_ON_RES    = 1 << 14, ///< Slot acquire (on reserve) action is present
 };
 DECLARE_ENUM_AS_BIT_SET(TraceRestrictProgramActionsUsedFlags)
 
@@ -417,6 +419,7 @@ enum TraceRestrictProgramInputSlotPermissions {
 	TRPISP_PBS_RES_END_ACQ_DRY    = 1 << 4,  ///< Dry-run slot acquire (PBS reservations ending at this signal) is permitted
 	TRPISP_PBS_RES_END_RELEASE    = 1 << 5,  ///< Slot release (PBS reservations ending at this signal) is permitted
 	TRPISP_CHANGE_COUNTER         = 1 << 6,  ///< Change counter value is permitted
+	TRPISP_ACQUIRE_ON_RES         = 1 << 7,  ///< Slot acquire (reserving route) is permitted
 };
 DECLARE_ENUM_AS_BIT_SET(TraceRestrictProgramInputSlotPermissions)
 

src/tracerestrict_gui.cpp

@@ -722,6 +722,7 @@ static const StringID _slot_op_cond_ops_str[] = {
 	STR_TRACE_RESTRICT_SLOT_PBS_RES_END_ACQUIRE_WAIT,
 	STR_TRACE_RESTRICT_SLOT_PBS_RES_END_TRY_ACQUIRE,
 	STR_TRACE_RESTRICT_SLOT_PBS_RES_END_RELEASE,
+	STR_TRACE_RESTRICT_SLOT_TRY_ACQUIRE_ON_RES,
 	INVALID_STRING_ID,
 };
 static const uint _slot_op_cond_ops_val[] = {
@@ -732,6 +733,7 @@ static const uint _slot_op_cond_ops_val[] = {
 	TRSCOF_PBS_RES_END_ACQ_WAIT,
 	TRSCOF_PBS_RES_END_ACQ_TRY,
 	TRSCOF_PBS_RES_END_RELEASE,
+	TRSCOF_ACQUIRE_TRY_ON_RESERVE,
 };
 /** cargo conditional operators dropdown list set */
 static const TraceRestrictDropDownListSet _slot_op_cond_ops = {
@@ -1409,6 +1411,10 @@ static void DrawInstructionString(const TraceRestrictProgram *prog, TraceRestric
 						instruction_string = STR_TRACE_RESTRICT_SLOT_PBS_RES_END_RELEASE_ITEM;
 						break;
 
+					case TRSCOF_ACQUIRE_TRY_ON_RESERVE:
+						instruction_string = STR_TRACE_RESTRICT_SLOT_TRY_ACQUIRE_ITEM_RES_ONLY;
+						break;
+
 					default:
 						NOT_REACHED();
 						break;

src/train_cmd.cpp

@@ -4067,10 +4067,10 @@ static Track ChooseTrainTrack(Train *v, TileIndex tile, DiagDirection enterdir,
 		if (track != INVALID_TRACK && HasPbsSignalOnTrackdir(tile, TrackEnterdirToTrackdir(track, enterdir))) {
 			if (IsRestrictedSignal(tile) && v->force_proceed != TFP_SIGNAL) {
 				const TraceRestrictProgram *prog = GetExistingTraceRestrictProgram(tile, track);
-				if (prog && prog->actions_used_flags & (TRPAUF_WAIT_AT_PBS | TRPAUF_SLOT_ACQUIRE | TRPAUF_TRAIN_NOT_STUCK)) {
+				if (prog && prog->actions_used_flags & (TRPAUF_WAIT_AT_PBS | TRPAUF_SLOT_ACQUIRE | TRPAUF_SLOT_ACQUIRE_ON_RES | TRPAUF_TRAIN_NOT_STUCK)) {
 					TraceRestrictProgramResult out;
 					TraceRestrictProgramInput input(tile, TrackEnterdirToTrackdir(track, enterdir), nullptr, nullptr);
-					input.permitted_slot_operations = TRPISP_ACQUIRE;
+					input.permitted_slot_operations = TRPISP_ACQUIRE | TRPISP_ACQUIRE_ON_RES;
 					prog->Execute(v, input, out);
 					if (out.flags & TRPRF_TRAIN_NOT_STUCK) {
 						v->wait_counter = 0;