Merge pull request #5039 from Goober5000/object_iteration_fixes

more robust object iteration

Author: Goober5000

code/object/object.h

@@ -15,6 +15,7 @@
 #include "globalincs/globals.h"
 #include "globalincs/pstypes.h"
 #include "math/vecmat.h"
+#include "object/object.h"
 #include "object/object_flags.h"
 #include "physics/physics.h"
 #include "utils/event.h"
@@ -159,13 +160,30 @@ class object
 	object& operator= (const object & other); // no implementation
 };
 
+extern int Num_objects;
+extern object Objects[];
+
 struct object_h {
 	object *objp;
 	int sig;
 
 	bool IsValid() const {return (objp != NULL && objp->signature == sig && sig > 0);}
-	object_h(object *in){objp=in; if(objp!=NULL){sig=in->signature;}}
+	object_h(object *in){objp=in; sig = (in == nullptr) ? -1 : in->signature;}
 	object_h(){objp=NULL;sig=-1;}
+
+	object_h(int objnum)
+	{
+		if (objnum >= 0 && objnum < MAX_OBJECTS)
+		{
+			objp = &Objects[objnum];
+			sig = objp->signature;
+		}
+		else
+		{
+			objp = nullptr;
+			sig = -1;
+		}
+	}
 };
 
 // object backup struct used by Fred.
@@ -194,13 +212,10 @@ class checkobject
 extern int Object_inited;
 extern int Show_waypoints;
 
-// The next signature for the next newly created object. Zero is bogus
-extern int Object_next_signature;		
-extern int Num_objects;
-
-extern object Objects[];
+extern int Object_next_signature;		// The next signature for the next newly created object. Zero is bogus
 extern int Highest_object_index;		//highest objnum
 extern int Highest_ever_object_index;
+
 extern object obj_free_list;
 extern object obj_used_list;
 extern object obj_create_list;

code/scripting/api/libs/mission.cpp

@@ -83,10 +83,47 @@ extern TIMESTAMP Game_shudder_time;
 extern int Game_shudder_total;
 extern float Game_shudder_intensity;
 
+constexpr int COUNT_OBJECTS = -1000;
+
+// Returns the indexth object subclass
+template <typename A>
+int object_subclass_at_index(A& object_subclass_array, size_t array_size, int index)
+{
+	int count = 0;
+
+	for (size_t i = 0; i < array_size; ++i)
+	{
+		int objnum = object_subclass_array[i].objnum;
+		if (objnum < 0 || objnum >= MAX_OBJECTS)
+			continue;
+		if (Objects[objnum].flags[Object::Object_Flags::Should_be_dead])
+			continue;
+
+		++count;
+
+		if (count == index)
+		{
+			return object_subclass_array[i].objnum;
+		}
+	}
+
+	if (index == COUNT_OBJECTS)
+		return count;
+	else
+		return -1;
+}
+
+// Counts the number of indexable objects
+template <typename A>
+int object_subclass_count(A& object_subclass_array, size_t array_size)
+{
+	return object_subclass_at_index(object_subclass_array, array_size, COUNT_OBJECTS);
+}
+
+
 namespace scripting {
 namespace api {
 
-
 //**********LIBRARY: Mission
 ADE_LIB(l_Mission, "Mission", "mn", "Mission library");
 
@@ -185,12 +222,12 @@ ADE_INDEXER(l_Mission_Asteroids, "number Index", "Gets asteroid", "asteroid", "A
 	if( !ade_get_args(L, "*i", &idx) ) {
 		return ade_set_error( L, "o", l_Asteroid.Set( object_h() ) );
 	}
-	if( idx > -1 && idx < asteroid_count() ) {
-		idx--; //Convert from Lua to C, as lua indices start from 1, not 0
-		return ade_set_args(L, "o", l_Asteroid.Set(object_h(&Objects[Asteroids[idx].objnum])));
-	}
 
-	return ade_set_error(L, "o", l_Asteroid.Set( object_h() ) );
+	int objnum = -1;
+	if (idx > 0)
+		objnum = object_subclass_at_index(Asteroids, MAX_ASTEROIDS, idx);
+
+	return ade_set_args(L, "o", l_Asteroid.Set( object_h(objnum) ) );
 }
 
 ADE_FUNC(__len, l_Mission_Asteroids, NULL,
@@ -199,7 +236,7 @@ ADE_FUNC(__len, l_Mission_Asteroids, NULL,
 		 "Number of asteroids in the mission, or 0 if asteroids are not enabled")
 {
 	if(Asteroids_enabled) {
-		return ade_set_args(L, "i", asteroid_count());
+		return ade_set_args(L, "i", object_subclass_count(Asteroids, MAX_ASTEROIDS));
 	}
 	return ade_set_args(L, "i", 0);
 }
@@ -383,32 +420,20 @@ ADE_INDEXER(l_Mission_Ships, "number/string IndexOrName", "Gets ship", "ship", "
 
 	int idx = ship_name_lookup(name);
 
-	if(idx > -1)
+	if (idx >= 0)
 	{
 		return ade_set_args(L, "o", l_Ship.Set(object_h(&Objects[Ships[idx].objnum])));
 	}
 	else
 	{
 		idx = atoi(name);
-		if(idx > 0)
-		{
-			int count=1;
 
-			for(int i = 0; i < MAX_SHIPS; i++)
-			{
-				if (Ships[i].objnum < 0 || Objects[Ships[i].objnum].type != OBJ_SHIP)
-					continue;
-
-				if(count == idx) {
-					return ade_set_args(L, "o", l_Ship.Set(object_h(&Objects[Ships[i].objnum])));
-				}
+		int objnum = -1;
+		if (idx > 0)
+			objnum = object_subclass_at_index(Ships, MAX_SHIPS, idx);
 
-				count++;
-			}
-		}
+		return ade_set_args(L, "o", l_Ship.Set(object_h(objnum)));
 	}
-
-	return ade_set_error(L, "o", l_Ship.Set(object_h()));
 }
 
 ADE_FUNC(__len, l_Mission_Ships, NULL,
@@ -418,10 +443,7 @@ ADE_FUNC(__len, l_Mission_Ships, NULL,
 		 "number",
 		 "Number of ships in the mission, or 0 if ships haven't been initialized yet")
 {
-	if(Ships_inited)
-		return ade_set_args(L, "i", ship_get_num_ships());
-	else
-		return ade_set_args(L, "i", 0);
+	return ade_set_args(L, "i", object_subclass_count(Ships, MAX_SHIPS));
 }
 
 //****SUBLIBRARY: Mission/ParsedShips
@@ -479,7 +501,7 @@ ADE_INDEXER(l_Mission_Waypoints, "number Index", "Array of waypoints in the curr
 	object *ptr = GET_FIRST(&obj_used_list);
 	while (ptr != END_OF_LIST(&obj_used_list))
 	{
-		if (ptr->type == OBJ_WAYPOINT)
+		if (ptr->type == OBJ_WAYPOINT && !ptr->flags[Object::Object_Flags::Should_be_dead])
 			count++;
 
 		if(count == idx) {
@@ -494,11 +516,15 @@ ADE_INDEXER(l_Mission_Waypoints, "number Index", "Array of waypoints in the curr
 
 ADE_FUNC(__len, l_Mission_Waypoints, NULL, "Gets number of waypoints in mission. Note that this is only accurate for one frame.", "number", "Number of waypoints in the mission")
 {
-	uint count=0;
-	for(uint i = 0; i < MAX_OBJECTS; i++)
+	int count=0;
+
+	object *ptr = GET_FIRST(&obj_used_list);
+	while (ptr != END_OF_LIST(&obj_used_list))
 	{
-		if (Objects[i].type == OBJ_WAYPOINT)
+		if (ptr->type == OBJ_WAYPOINT && !ptr->flags[Object::Object_Flags::Should_be_dead])
 			count++;
+
+		ptr = GET_NEXT(ptr);
 	}
 
 	return ade_set_args(L, "i", count);
@@ -546,26 +572,15 @@ ADE_INDEXER(l_Mission_Weapons, "number Index", "Gets handle to a weapon object i
 	if(!ade_get_args(L, "*i", &idx))
 		return ade_set_error(L, "o", l_Weapon.Set(object_h()));
 
-	//Remember, Lua indices start at 0.
-	int count=1;
-
-	for(int i = 0; i < MAX_WEAPONS; i++)
-	{
-		if (Weapons[i].weapon_info_index < 0 || Weapons[i].objnum < 0 || Objects[Weapons[i].objnum].type != OBJ_WEAPON)
-			continue;
-
-		if(count == idx) {
-			return ade_set_args(L, "o", l_Weapon.Set(object_h(&Objects[Weapons[i].objnum])));
-		}
-
-		count++;
-	}
+	int objnum = -1;
+	if (idx > 0)
+		objnum = object_subclass_at_index(Weapons, MAX_WEAPONS, idx);
 
-	return ade_set_error(L, "o", l_Weapon.Set(object_h()));
+	return ade_set_args(L, "o", l_Weapon.Set(object_h(objnum)));
 }
 ADE_FUNC(__len, l_Mission_Weapons, NULL, "Number of weapon objects in mission. Note that this is only accurate for one frame.", "number", "Number of weapon objects in mission")
 {
-	return ade_set_args(L, "i", Num_weapons);
+	return ade_set_args(L, "i", object_subclass_count(Weapons, MAX_WEAPONS));
 }
 
 //****SUBLIBRARY: Mission/Beams
@@ -577,26 +592,15 @@ ADE_INDEXER(l_Mission_Beams, "number Index", "Gets handle to a beam object in th
 	if(!ade_get_args(L, "*i", &idx))
 		return ade_set_error(L, "o", l_Beam.Set(object_h()));
 
-	//Remember, Lua indices start at 0.
-	int count=1;
-
-	for(int i = 0; i < MAX_BEAMS; i++)
-	{
-		if (Beams[i].weapon_info_index < 0 || Beams[i].objnum < 0 || Objects[Beams[i].objnum].type != OBJ_BEAM)
-			continue;
-
-		if(count == idx) {
-			return ade_set_args(L, "o", l_Beam.Set(object_h(&Objects[Beams[i].objnum])));
-		}
-
-		count++;
-	}
+	int objnum = -1;
+	if (idx > 0)
+		objnum = object_subclass_at_index(Beams, MAX_BEAMS, idx);
 
-	return ade_set_error(L, "o", l_Beam.Set(object_h()));
+	return ade_set_args(L, "o", l_Beam.Set(object_h(objnum)));
 }
 ADE_FUNC(__len, l_Mission_Beams, NULL, "Number of beam objects in mission. Note that this is only accurate for one frame.", "number", "Number of beam objects in mission")
 {
-	return ade_set_args(L, "i", Beam_count);
+	return ade_set_args(L, "i", object_subclass_count(Beams, MAX_BEAMS));
 }
 
 //****SUBLIBRARY: Mission/Wings
@@ -796,27 +800,15 @@ ADE_INDEXER(l_Mission_Fireballs, "number Index", "Gets handle to a fireball obje
 	if (!ade_get_args(L, "*i", &idx))
 		return ade_set_error(L, "o", l_Fireball.Set(object_h()));
 
-	//Remember, Lua indices start at 1.
-	int count = 1;
-
-	for (auto& current_fireball : Fireballs) {
-		if (current_fireball.fireball_info_index < 0 || current_fireball.objnum < 0 || Objects[current_fireball.objnum].type != OBJ_FIREBALL)
-			continue;
-
-		if (count == idx) {
-			return ade_set_args(L, "o", l_Fireball.Set(object_h(&Objects[current_fireball.objnum])));
-		}
-
-		count++;
-
-	}
+	int objnum = -1;
+	if (idx > 0)
+		objnum = object_subclass_at_index(Fireballs, MAX_FIREBALLS, idx);
 
-	return ade_set_error(L, "o", l_Fireball.Set(object_h()));
+	return ade_set_args(L, "o", l_Fireball.Set(object_h(objnum)));
 }
 ADE_FUNC(__len, l_Mission_Fireballs, NULL, "Number of fireball objects in mission. Note that this is only accurate for one frame.", "number", "Number of fireball objects in mission")
 {
-	int count = fireball_get_count();
-	return ade_set_args(L, "i", count);
+	return ade_set_args(L, "i", object_subclass_count(Fireballs, MAX_FIREBALLS));
 }
 
 ADE_FUNC(addMessage, l_Mission, "string name, string text, [persona persona]", "Adds a message", "message", "The new message or invalid handle on error")
@@ -2223,6 +2215,16 @@ ADE_FUNC(getShipList,
 		//Similarly, an empty list is defined by the head's next element being itself, hence an empty list will immediately return nil just fine
 		so = GET_NEXT(so);
 
+		// skip should-be-dead ships
+		if (so != nullptr) {
+			while (so != END_OF_LIST(&Ship_obj_list)) {
+				if (!Objects[so->objnum].flags[Object::Object_Flags::Should_be_dead]) {
+					break;
+				}
+				so = GET_NEXT(so);
+			}
+		}
+
 		if (so == END_OF_LIST(&Ship_obj_list) || so == nullptr) {
 			return luacpp::LuaValueList{ luacpp::LuaValue::createNil(LInner) };
 		}
@@ -2245,6 +2247,16 @@ ADE_FUNC(getMissileList,
 		//Similarly, an empty list is defined by the head's next element being itself, hence an empty list will immediately return nil just fine
 		mo = GET_NEXT(mo);
 
+		// skip should-be-dead missiles
+		if (mo != nullptr) {
+			while (mo != END_OF_LIST(&Missile_obj_list)) {
+				if (!Objects[mo->objnum].flags[Object::Object_Flags::Should_be_dead]) {
+					break;
+				}
+				mo = GET_NEXT(mo);
+			}
+		}
+
 		if (mo == END_OF_LIST(&Missile_obj_list) || mo == nullptr) {
 			return luacpp::LuaValueList{ luacpp::LuaValue::createNil(LInner) };
 		}

code/scripting/api/objs/object.cpp

@@ -300,6 +300,18 @@ ADE_FUNC(isValid, l_Object, NULL, "Detects whether handle is valid", "boolean",
 	return ade_set_args(L, "b", oh->IsValid());
 }
 
+ADE_FUNC(isExpiring, l_Object, nullptr, "Checks whether the object has the should-be-dead flag set, which will cause it to be deleted within one frame", "boolean", "true or false according to the flag, or nil if a syntax/type error occurs")
+{
+	object_h* oh;
+	if (!ade_get_args(L, "o", l_Object.GetPtr(&oh)))
+		return ADE_RETURN_NIL;
+
+	if (!oh->IsValid())
+		return ADE_RETURN_NIL;
+
+	return ade_set_args(L, "b", oh->objp->flags[Object::Object_Flags::Should_be_dead]);
+}
+
 ADE_FUNC(getBreedName, l_Object, NULL, "Gets object type", "string", "Object type name, or empty string if handle is invalid")
 {
 	object_h *objh;