Fix netsync of race checkpoints and associated map lines

- Use srb2::MobjList to keep checkpoint objects list
  intact after savegame load
- Use std::unordered_map of line tag and vector of line_t
  pointers
  - Use line tag for the key so multiple checkpoints may
    be associated to the same set of lines

src/objects/checkpoint.cpp

@@ -9,6 +9,8 @@
 //-----------------------------------------------------------------------------
 
 #include <algorithm>
+#include <unordered_map>
+#include <vector>
 
 #include <fmt/format.h>
 
@@ -35,8 +37,6 @@
 #include "../sounds.h"
 #include "../tables.h"
 
-using std::vector;
-using std::pair;
 using std::min;
 using std::max;
 using std::clamp;
@@ -45,7 +45,6 @@ extern mobj_t* svg_checkpoints;
 
 #define checkpoint_id(o) ((o)->thing_args[0])
 #define checkpoint_linetag(o) ((o)->thing_args[1])
-#define checkpoint_extralength(o) ((o)->thing_args[2])
 #define checkpoint_other(o) ((o)->target)
 #define checkpoint_orb(o) ((o)->tracer)
 #define checkpoint_arm(o) ((o)->hnext)
@@ -132,6 +131,7 @@ struct Checkpoint : mobj_t
 	struct Arm : mobj_t {};
 
 	INT32 id() const { return checkpoint_id(this); }
+	INT32 linetag() const { return checkpoint_linetag(this); }
 
 	Checkpoint* other() const { return static_cast<Checkpoint*>(checkpoint_other(this)); }
 	void other(Checkpoint* n) { P_SetTarget(&checkpoint_other(this), n); }
@@ -453,39 +453,16 @@ struct CheckpointManager
 	auto begin() { return list_.begin(); }
 	auto end() { return list_.end(); }
 
-	auto find_checkpoint(INT32 id) {
+	auto find_checkpoint(INT32 id)
-		auto it = find_if(list_.begin(), list_.end(), [id](auto pair) { return pair.first->id() == id; });
+	{
-		if (it != list_.end())
+		auto it = std::find_if(begin(), end(), [id](Checkpoint* chk) { return chk->id() == id; });
-		{
+		return it != end() ? *it : nullptr;
-			return it->first;
+	}
-		}
+
-		return static_cast<Checkpoint*>(nullptr);
+	void remove_checkpoint(Checkpoint* end) { list_.erase(end); }
-	}
+
-
+	void link_checkpoint(Checkpoint* chk)
-	// auto find_pair(Checkpoint* chk) {
-	// 	pair<Checkpoint*, vector<line_t*>> retpair;
-	// 	auto it = find_if(list_.begin(), list_.end(), [chk](auto pair) { return pair.first == chk; });
-	// 	if (it != list_.end())
-	// 	{
-	// 		retpair = *it;
-	// 		return retpair;
-	// 	}
-	// 	return static_cast<pair<Checkpoint*, vector<line_t*>>>(nullptr);
-	// }
-
-	void remove_checkpoint(mobj_t* end) 
-	{ 
-		auto chk = static_cast<Checkpoint*>(end);
-		auto it = find_if(list_.begin(), list_.end(), [&](auto pair) { return pair.first == chk; });
-		if (it != list_.end())
-		{
-			list_.erase(it);
-		}
-	}
-
-	void link_checkpoint(mobj_t* end)
 	{
-		auto chk = static_cast<Checkpoint*>(end);
 		auto id = chk->id();
 		if (chk->spawnpoint && id == 0)
 			{
@@ -517,29 +494,39 @@ struct CheckpointManager
 		}
 		else // Checkpoint isn't in the list, find any associated tagged lines and make the pair
 		{
-			vector<line_t*> checklines;
+			if (chk->linetag())
-			if (checkpoint_linetag(chk))
+				lines_.try_emplace(chk->linetag(), std::move(tagged_lines(chk->linetag())));
-			{
+			list_.push_front(chk);
-				INT32 li;
-				INT32 tag = checkpoint_linetag(chk);
-				TAG_ITER_LINES(tag, li)
-				{
-					line_t* line = lines + li;
-					checklines.push_back(line);
-				}
-			}
-			list_.emplace_back(chk, move(checklines));
 		}
 
 		chk->gingerbread();
 	}
 
-	void clear() { list_.clear(); }
+	void clear() { lines_.clear(); }
 
-	auto count() { return list_.size(); }
+	auto count() { return list_.count(); }
+
+	const std::vector<line_t*>* lines_for(const Checkpoint* chk) const
+	{
+		auto it = lines_.find(chk->linetag());
+		return it != lines_.end() ? &it->second : nullptr;
+	}
 
 private:
-	vector<pair<Checkpoint*, vector<line_t*>>> list_;
+	srb2::MobjList<Checkpoint, svg_checkpoints> list_;
+	std::unordered_map<INT32, std::vector<line_t*>> lines_;
+
+	static std::vector<line_t*> tagged_lines(INT32 tag)
+	{
+		std::vector<line_t*> checklines;
+		INT32 li;
+		TAG_ITER_LINES(tag, li)
+		{
+			line_t* line = lines + li;
+			checklines.push_back(line);
+		}
+		return checklines;
+	}
 };
 
 CheckpointManager g_checkpoints;
@@ -548,13 +535,13 @@ CheckpointManager g_checkpoints;
 
 void Obj_LinkCheckpoint(mobj_t* end)
 {
-	g_checkpoints.link_checkpoint(end);
+	g_checkpoints.link_checkpoint(static_cast<Checkpoint*>(end));
 }
 
 void Obj_UnlinkCheckpoint(mobj_t* end)
 {
 	auto chk = static_cast<Checkpoint*>(end);
-	g_checkpoints.remove_checkpoint(end);
+	g_checkpoints.remove_checkpoint(chk);
 	P_RemoveMobj(chk->orb());
 	P_RemoveMobj(chk->arm());
 }
@@ -575,20 +562,20 @@ void __attribute__((optimize("O0"))) Obj_CrossCheckpoints(player_t* player, fixe
 {
 	LineOnDemand ray(old_x, old_y, player->mo->x, player->mo->y, player->mo->radius);
 
-	auto it = find_if(
+	auto it = std::find_if(
 		g_checkpoints.begin(),
 		g_checkpoints.end(),
-		[&](auto chkpair)
+		[&](Checkpoint* chk)
 		{
-			Checkpoint* chk = chkpair.first;
 			if (!chk->valid())
 			{
 				return false;
 			}
 
 			LineOnDemand* gate;
+			const std::vector<line_t*>* lines = g_checkpoints.lines_for(chk);
 
-			if (chkpair.second.empty())
+			if (!lines || lines->empty())
 			{
 				LineOnDemand dyngate = chk->crossing_line();
 				if (!ray.overlaps(dyngate))
@@ -598,15 +585,15 @@ void __attribute__((optimize("O0"))) Obj_CrossCheckpoints(player_t* player, fixe
 			else 
 			{
 				auto it = find_if(
-					chkpair.second.begin(),
+					lines->begin(),
-					chkpair.second.end(),
+					lines->end(),
 					[&](const line_t* line)
 					{
 						return ray.overlaps(*line);
 					}
 				);
 				
-				if (it == chkpair.second.end())
+				if (it == lines->end())
 				{
 					return false;
 				}
@@ -640,7 +627,7 @@ void __attribute__((optimize("O0"))) Obj_CrossCheckpoints(player_t* player, fixe
 		return;
 	}
 
-	Checkpoint* chk = it->first;
+	Checkpoint* chk = *it;
 
 	if (player->checkpointId == chk->id())
 	{
@@ -657,9 +644,8 @@ void __attribute__((optimize("O0"))) Obj_CrossCheckpoints(player_t* player, fixe
 
 	if (gametyperules & GTR_CHECKPOINTS)
 	{
-		for (auto chkpair : g_checkpoints)
+		for (Checkpoint* chk : g_checkpoints)
 		{
-			Checkpoint* chk = chkpair.first;
 			if (chk->valid())
 			{
 				chk->untwirl();
@@ -741,13 +727,12 @@ void Obj_ClearCheckpoints()
 
 void Obj_DeactivateCheckpoints()
 {
-	for (auto chkpair : g_checkpoints)
+	for (Checkpoint* chk : g_checkpoints)
 	{
-		Checkpoint* chk = chkpair.first;
 		if (chk->valid())
 		{
 			chk->untwirl();
 			chk->other()->untwirl();
 		}
 	}
-}
+}