Improve deletion

demo/src/StarterPlayer/StarterPlayerScripts/systems/lol.luau

@@ -0,0 +1,67 @@
+--!optimize 2
+--!native
+--!strict
+
+local ReplicatedStorage = game:GetService("ReplicatedStorage")
+local jecs = require(ReplicatedStorage.ecs)
+local __ = jecs.Wildcard
+local std = ReplicatedStorage.std
+
+local world = require(std.world)
+
+local Position = world:component() :: jecs.Entity<vector>
+local Previous = jecs.Rest
+local pre = jecs.pair(Position, Previous)
+
+local added = world
+	:query(Position)
+	:without(pre)
+	:cached()
+local changed = world
+	:query(Position, pre)
+	:cached()
+local removed = world
+	:query(pre)
+	:without(Position)
+	:cached()
+
+local children = {}
+for i = 1, 10 do
+	local e = world:entity()
+	world:set(e, Position, vector.create(i, i, i))
+	table.insert(children, e)
+end
+local function flip()
+	return math.random() > 0.5
+end
+local function system()
+	for i, child in children do
+		world:set(child, Position, vector.create(i,i,i))
+	end
+	for e, p in added:iter() do
+		world:set(e, pre, p)
+	end
+	for i, child in children do
+		if flip() then
+			world:set(child, Position, vector.create(i + 1, i + 1, i + 1))
+		end
+	end
+	for e, new, old in changed:iter() do
+		if new ~= old then
+			world:set(e, pre, new)
+		end
+	end
+
+	for i, child in children do
+		world:remove(child, Position)
+	end
+
+	for e in removed:iter() do
+		world:remove(e, pre)
+	end
+end
+local scheduler = require(std.scheduler)
+
+scheduler.SYSTEM(system)
+
+return 0

demo/src/StarterPlayer/StarterPlayerScripts/systems/lol2.luau

@@ -0,0 +1,90 @@
+--!optimize 2
+--!native
+--!strict
+
+local ReplicatedStorage = game:GetService("ReplicatedStorage")
+local jecs = require(ReplicatedStorage.ecs)
+local __ = jecs.Wildcard
+local std = ReplicatedStorage.std
+
+local world = require(std.world)
+
+local Position = world:component() :: jecs.Entity<vector>
+local Previous = jecs.Rest
+local pre = jecs.pair(Position, Previous)
+
+local added = world
+	:query(Position)
+	:without(pre)
+	:cached()
+local changed = world
+	:query(Position, pre)
+	:cached()
+local removed = world
+	:query(pre)
+	:without(Position)
+	:cached()
+
+local children = {}
+for i = 1, 10 do
+	local e = world:entity()
+	world:set(e, Position, vector.create(i, i, i))
+	table.insert(children, e)
+end
+local function flip()
+	return math.random() > 0.5
+end
+local entity_index = world.entity_index
+local function copy(archetypes, id)
+	for _, archetype in archetypes do
+
+		local to = jecs.archetype_traverse_add(world, pre, archetype)
+		local columns = to.columns
+		local records = to.records
+		local old = columns[records[pre].column]
+		local new =	columns[records[id].column]
+
+		if to ~= archetype then
+			for _, entity in archetype.entities do
+				local r = jecs.entity_index_try_get_fast(entity_index, entity)
+				jecs.entity_move(entity_index, entity, r, to)
+			end
+		end
+
+		table.move(new, 1, #new, 1, old)
+
+	end
+end
+local function system2()
+	for i, child in children do
+		world:set(child, Position, vector.create(i,i,i))
+	end
+	for e, p in added:iter() do
+	end
+	copy(added:archetypes(), Position)
+	for i, child in children do
+		if flip() then
+			world:set(child, Position, vector.create(i + 1, i + 1, i + 1))
+		end
+	end
+
+	for e, new, old in changed:iter() do
+		if new ~= old then
+		end
+	end
+
+	copy(changed:archetypes(), Position)
+
+	for i, child in children do
+		world:remove(child, Position)
+	end
+
+	for e in removed:iter() do
+		world:remove(e, pre)
+	end
+end
+local scheduler = require(std.scheduler)
+
+scheduler.SYSTEM(system2)
+
+return 0

examples/luau/queries/changetracking.luau

@@ -1,4 +1,5 @@
 local jecs = require("@jecs")
+local pair = jecs.pair
 
 local world = jecs.World.new()
 local Name = world:component()
@@ -12,46 +13,44 @@ local function name(e)
 	return world:get(e, Name)
 end
 
-local Position = named(world.component, "Position") :: jecs.Entity<Vector3>
+local Position = named(world.component, "Position") :: jecs.Entity<vector>
 local Previous = jecs.Rest
-local PreviousPosition = jecs.pair(Previous, Position)
 
 local added = world
 	:query(Position)
-	:without(PreviousPosition)
+	:without(pair(Previous, Position))
 	:cached()
 local changed = world
-	:query(Position, PreviousPosition)
+	:query(Position, pair(Previous, Position))
 	:cached()
 local removed = world
-	:query(PreviousPosition)
+	:query(pair(Previous, Position))
 	:without(Position)
 	:cached()
 
 local e1 = named(world.entity, "e1")
-world:set(e1, Position, Vector3.new(10, 20, 30))
-
+world:set(e1, Position, vector.create(10, 20, 30))
 local e2 = named(world.entity, "e2")
-world:set(e2, Position, Vector3.new(10, 20, 30))
-
-for e, p in added:iter() do
-	print(`Added {e}: \{{p.X}, {p.Y}, {p.Z}}`)
-	world:set(e, PreviousPosition, p)
+world:set(e2, Position, vector.create(10, 20, 30))
+for entity, p in added do
+	print(`Added {name(entity)}: \{{p.x}, {p.y}, {p.z}}`)
+	world:set(entity, pair(Previous, Position), p)
 end
 
-world:set(e1, Position, "")
+world:set(e1, Position, vector.create(999, 999, 1998))
 
-for e, new, old in changed:iter() do
+for e, new, old in changed do
 	if new ~= old then
-		print(`{name(new)}'s Position changed from \{{old.X}, {old.Y}, {old.Z}\} to \{{new.X}, {new.Y}, {new.Z}\}`)
-		world:set(e, PreviousPosition, new)
+		print(`{name(e)}'s Position changed from \{{old.x}, {old.y}, {old.z}\} to \{{new.x}, {new.y}, {new.z}\}`)
+		world:set(e, pair(Previous, Position), new)
 	end
 end
 
 world:remove(e2, Position)
 
 for e in removed:iter() do
 	print(`Position was removed from {name(e)}`)
+	world:remove(e, pair(Previous, Position))
 end
 
 -- Output:

jecs.luau

@@ -1144,6 +1144,9 @@ do
 			end
 		end
 
+		local sparse_array = entity_index.sparse_array
+		local dense_array = entity_index.dense_array
+
 		if idr_t then
 			for archetype_id in idr_t.cache do
 				local children = {}
@@ -1174,24 +1177,14 @@ do
 						else
 							local on_remove = id_record.hooks.on_remove
 							local to = archetype_traverse_remove(world, id, idr_t_archetype)
-							if on_remove then
-								if to then
-									for i = n, 1, -1 do
-										local child = children[i]
-										on_remove(children[i])
-										local r = entity_index_try_get_fast(entity_index, child) :: Record
-										entity_move(entity_index, child, r, to)
-									end
-								else
-									for i = n, 1, -1 do
-										local child = children[i]
-										on_remove(child)
-									end
+							local empty = #to.types == 0
+							for i = n, 1, -1 do
+								local child = children[i]
+								if on_remove then
+									on_remove(child)
 								end
-							elseif to then
-								for i = n, 1, -1 do
-									local child = children[i]
-									local r = entity_index_try_get_fast(entity_index, child) :: Record
+								local r = sparse_array[ECS_ENTITY_T_LO(child)]
+								if not empty then
 									entity_move(entity_index, child, r, to)
 								end
 							end
@@ -1203,7 +1196,6 @@ do
 			end
 		end
 
-		local dense_array = entity_index.dense_array
 		local index_of_deleted_entity = record.dense
 		local index_of_last_alive_entity = entity_index.alive_count
 		entity_index.alive_count = index_of_last_alive_entity - 1
@@ -2362,6 +2354,8 @@ return {
 	archetype_traverse_add = archetype_traverse_add,
 	archetype_traverse_remove = archetype_traverse_remove,
 
+	entity_move = entity_move,
+
 	entity_index_try_get = entity_index_try_get,
 	entity_index_try_get_any = entity_index_try_get_any,
 	entity_index_try_get_fast = entity_index_try_get_fast,

test/tests.luau

@@ -1045,6 +1045,21 @@ TEST("world:component()", function()
 end)
 
 TEST("world:delete", function()
+	do CASE "delete recycled entity id used as component"
+		local world = world_new()
+		local id = world:entity()
+		world:add(id, jecs.Component)
+
+		local e = world:entity()
+		world:set(e, id, 1)
+		CHECK(world:get(e, id) == 1)
+		world:delete(id)
+		local recycled = world:entity()
+		world:add(recycled, jecs.Component)
+		world:set(e, recycled, 1)
+		CHECK(world:has(recycled, jecs.Component))
+		CHECK(world:get(e, recycled) == 1)
+	end
 	do
 		CASE("bug: Empty entity does not respect cleanup policy")
 		local world = world_new()