Progsig: Fix various issues with removing program dependencies.

Fix RemoveProgramDependencies using one parameter for both source
and target, and rename the parameters to something sensible.
Update program window when invalidating in RemoveProgramDependencies.
Make SignalStateCondition::IsSignalValid const and add CheckSignalValid
for non-const validaty checking.

src/programmable_signals.cpp

@@ -121,21 +121,23 @@ SignalStateCondition::SignalStateCondition(SignalReference this_sig,
 	: SignalCondition(PSC_SIGNAL_STATE), this_sig(this_sig), sig_tile(sig_tile)
 	, sig_track(sig_track)
 {
-	if (this->IsSignalValid())
+	if (this->CheckSignalValid())
 		AddSignalDependency(SignalReference(this->sig_tile, TrackdirToTrack(sig_track)),
 																				this->this_sig);
 }
 
-bool SignalStateCondition::IsSignalValid()
+bool SignalStateCondition::IsSignalValid() const
 {
-	if (IsValidTile(this->sig_tile)) {
-		if (IsTileType(this->sig_tile, MP_RAILWAY) && HasSignalOnTrackdir(this->sig_tile, this->sig_track)) {
-			return true;
-		} else {
-			Invalidate();
-		}
+	return IsValidTile(this->sig_tile) && IsTileType(this->sig_tile, MP_RAILWAY) && HasSignalOnTrackdir(this->sig_tile, this->sig_track);
+}
+
+bool SignalStateCondition::CheckSignalValid()
+{
+	bool valid = this->IsSignalValid();
+	if (!valid) {
+		this->Invalidate();
 	}
-	return false;
+	return valid;
 }
 
 void SignalStateCondition::Invalidate()
@@ -151,7 +153,7 @@ void SignalStateCondition::SetSignal(TileIndex tile, Trackdir track)
 																					 this->this_sig);
 	this->sig_tile = tile;
 	this->sig_track = track;
-	if (this->IsSignalValid())
+	if (this->CheckSignalValid())
 		AddSignalDependency(SignalReference(this->sig_tile, TrackdirToTrack(sig_track)),
 																				this->this_sig);
 }
@@ -165,7 +167,7 @@ void SignalStateCondition::SetSignal(TileIndex tile, Trackdir track)
 
 /*virtual*/ bool SignalStateCondition::Evaluate(SignalVM& vm)
 {
-	if (!this->IsSignalValid()) {
+	if (!this->CheckSignalValid()) {
 		DEBUG(misc, 1, "Signal (%x, %d) has an invalid condition", this->this_sig.tile, this->this_sig.track);
 		return false;
 	}
@@ -412,9 +414,9 @@ SignalState RunSignalProgram(SignalReference ref, uint num_exits, uint num_green
 	return vm.state;
 }
 
-void RemoveProgramDependencies(SignalReference by, SignalReference on)
+void RemoveProgramDependencies(SignalReference dependency_target, SignalReference signal_to_update)
 {
-	SignalProgram *prog = GetSignalProgram(by);
+	SignalProgram *prog = GetSignalProgram(signal_to_update);
 	for (SignalInstruction **b = prog->instructions.Begin(), **i = b, **e = prog->instructions.End();
 			i != e; i++) {
 		SignalInstruction *insn = *i;
@@ -422,13 +424,14 @@ void RemoveProgramDependencies(SignalReference by, SignalReference on)
 			SignalIf* ifi = static_cast<SignalIf*>(insn);
 			if (ifi->condition->ConditionCode() == PSC_SIGNAL_STATE) {
 				SignalStateCondition* c = static_cast<SignalStateCondition*>(ifi->condition);
-				if(c->sig_tile == by.tile && TrackdirToTrack(c->sig_track) == by.track)
+				if(c->sig_tile == dependency_target.tile && TrackdirToTrack(c->sig_track) == dependency_target.track)
 					c->Invalidate();
 				}
 			}
 		}
 
-	AddTrackToSignalBuffer(by.tile, by.track, GetTileOwner(by.tile));
+	InvalidateWindowData(WC_SIGNAL_PROGRAM, (signal_to_update.tile << 3) | signal_to_update.track);
+	AddTrackToSignalBuffer(signal_to_update.tile, signal_to_update.track, GetTileOwner(signal_to_update.tile));
 	UpdateSignalsInBuffer();
 }
 

src/programmable_signals.h

@@ -202,7 +202,8 @@ class SignalStateCondition: public SignalCondition {
 		SignalStateCondition(SignalReference this_sig, TileIndex sig_tile, Trackdir sig_track);
 
 		void SetSignal(TileIndex tile, Trackdir track);
-		bool IsSignalValid();
+		bool IsSignalValid() const;
+		bool CheckSignalValid();
 		void Invalidate();
 
 		virtual bool Evaluate(SignalVM& vm);
@@ -389,7 +390,7 @@ void FreeSignalPrograms();
 SignalState RunSignalProgram(SignalReference ref, uint num_exits, uint num_green);
 
 /// Remove dependencies on signal @p on from @p by
-void RemoveProgramDependencies(SignalReference by, SignalReference on);
+void RemoveProgramDependencies(SignalReference dependency_target, SignalReference signal_to_update);
 ///@}
 
 #endif

src/signal.cpp

@@ -768,11 +768,11 @@ void CheckRemoveSignalsFromTile(TileIndex tile)
 	}
 }
 
-static void NotifyRemovingDependentSignal(SignalReference on, SignalReference by)
+static void NotifyRemovingDependentSignal(SignalReference being_removed, SignalReference dependant)
 {
-	SignalType t = GetSignalType(by.tile, by.track);
+	SignalType t = GetSignalType(dependant.tile, dependant.track);
 	if (IsProgrammableSignal(t)) {
-		RemoveProgramDependencies(by, on);
+		RemoveProgramDependencies(being_removed, dependant);
 	} else {
 		DEBUG(misc, 0, "Removing dependency held by non-programmable signal (Unexpected)");
 	}