Index is not a stable pointer

ranges

CHANGELOG.md

@@ -11,6 +11,7 @@ The format is based on [Keep a Changelog][kac], and this project adheres to
 ## [Unreleased]
 
 -   `[world]`:
+    -   Added `world:range` to allow for creating
     -   Changed `world:clear` to also look through the component record for the cleared `ID`
         -   Removes the cleared ID from every entity that has it
     -   Changed entity ID layouts by putting the index in the lower bits, which should make every world function 1-5 nanoseconds faster

addons/observers.luau

@@ -24,7 +24,7 @@ local function observers_new(world, description)
 	end
 
 	local entity_index = world.entity_index :: any
-	local function emplaced(entity: jecs.Entity)
+	local function emplaced(entity, id, value)
 		local r = jecs.entity_index_try_get_fast(
 			entity_index, entity :: any)
 
@@ -45,6 +45,106 @@ local function observers_new(world, description)
  	end
 end
 
+
+local function join(world, component)
+	local sparse_array = {}
+	local dense_array = {}
+	local values = {}
+	local max_id = 0
+
+	world:added(component, function(entity, id, value)
+		max_id += 1
+		sparse_array[entity] = max_id
+		dense_array[max_id] = entity
+		values[max_id] = value
+	end)
+
+	world:removed(component, function(entity, id)
+		local e_swap = dense_array[max_id]
+		local v_swap = values[max_id]
+
+		local dense = sparse_array[entity]
+		dense_array[dense] = e_swap
+		values[dense] = v_swap
+
+		sparse_array[entity] = nil
+		dense_array[max_id] = nil
+		values[max_id] = nil
+	end)
+
+	world:changed(component, function(entity, id, value)
+		values[sparse_array[entity]] = value
+	end)
+
+	return function()
+		local i = max_id
+		return function(): ...any
+			i -= 1
+			if i == 0 then
+				return nil
+			end
+			local e = dense_array[i]
+			return e, values[i]
+		end
+	end
+end
+
+local function query_changed(world, component)
+	assert(jecs.IS_PAIR(component) == false)
+	local callerid = debug.info(2, "sl")
+
+	local tracker = world.trackers[callerid]
+	if not tracker then
+		local records = {}
+		local connections = {}
+		tracker = {
+			records = records,
+			connections = connections
+		}
+		world.trackers[callerid] = tracker
+
+		table.insert(connections, world:added(component, function(entity, id, v)
+			tracker[entity] = {
+				new = v
+			}
+		end))
+		table.insert(connections, world:changed(component, function(entity, id, v)
+			local record = tracker[entity]
+			record.old = record.new
+			record.new = v
+		end))
+
+		table.insert(connections, world:removed(component, function(entity, id)
+			local record = tracker[entity]
+			record.old = record.new
+			record.new = nil
+		end))
+	end
+
+	local entity = nil
+	local record = nil
+	return function()
+		entity, record = next(tracker, entity)
+		if entity == nil then
+			return
+		end
+		return entity, record
+	end
+end
+
+local function spy_on_world_delete(world)
+	local world_delete = world.delete
+	world.delete = function(world, entity)
+		world_delete(world, entity)
+		for _, tracker in world.trackers do
+			tracker.records[entity] = nil
+			for _, connection in tracker.connections do
+				connection()
+			end
+		end
+	end
+end
+
 local function monitors_new(world, description)
 	local query = description.query
 	local callback = description.callback
@@ -93,10 +193,11 @@ local function monitors_new(world, description)
 end
 
 local function observers_add(world: jecs.World & { [string]: any }): PatchedWorld
+	type Signal = { [jecs.Entity]: { (...any) -> () } }
 	local signals = {
-		added = {},
-		emplaced = {},
-		removed = {}
+		added = {} :: Signal,
+		emplaced = {} :: Signal,
+		removed = {} :: Signal
 	}
 
 	world.added = function(_, component, fn)
@@ -115,6 +216,12 @@ local function observers_add(world: jecs.World & { [string]: any }): PatchedWorl
 			world:set(component, jecs.OnAdd, on_add)
 		end
 		table.insert(listeners, fn)
+		return function()
+			local n = #listeners
+			local i = table.find(listeners, fn)
+			listeners[i] = listeners[n]
+			listeners[n] = nil
+		end
 	end
 
 	world.changed = function(_, component, fn)
@@ -132,6 +239,12 @@ local function observers_add(world: jecs.World & { [string]: any }): PatchedWorl
 			world:set(component, jecs.OnChange, on_change)
 		end
 		table.insert(listeners, fn)
+		return function()
+			local n = #listeners
+			local i = table.find(listeners, fn)
+			listeners[i] = listeners[n]
+			listeners[n] = nil
+		end
 	end
 
 	world.removed = function(_, component, fn)
@@ -149,6 +262,12 @@ local function observers_add(world: jecs.World & { [string]: any }): PatchedWorl
 			world:set(component, jecs.OnRemove, on_remove)
 		end
 		table.insert(listeners, fn)
+		return function()
+			local n = #listeners
+			local i = table.find(listeners, fn)
+			listeners[i] = listeners[n]
+			listeners[n] = nil
+		end
 	end
 
 	world.signals = signals
@@ -157,6 +276,8 @@ local function observers_add(world: jecs.World & { [string]: any }): PatchedWorl
 
 	world.monitor = monitors_new
 
+	world.trackers = {}
+
 	return world :: PatchedWorld
 end
 

benches/visual/spawn.bench.luau

@@ -5,23 +5,29 @@ local ReplicatedStorage = game:GetService("ReplicatedStorage")
 local jecs = require(ReplicatedStorage.Lib:Clone())
 local mirror = require(ReplicatedStorage.mirror:Clone())
 
-local ecs = jecs.World.new()
-local mcs = mirror.world()
+
 
 return {
 	ParameterGenerator = function()
+		local ecs = jecs.world()
+		ecs:range(1000, 20000)
+		local mcs = mirror.World.new()
+		return ecs, mcs
 	end,
 
 	Functions = {
-		Mirror = function() 
-			for i = 1000, 1100 do 
-				mcs:entity(i)
+		Mirror = function(_, ecs, mcs)
+			for i = 1, 100 do
+
+				mcs:entity()
 			end
 		end,
-		Jecs = function()
-			for i = 1, 1000 do
-				ecs:entity(i)
+
+		Jecs = function(_, ecs, mcs)
+			for i = 1, 100 do
+
+				ecs:entity()
 			end
 		end,
-	},
+},
 }

jecs.luau

@@ -120,7 +120,6 @@ local ECS_GENERATION_MASK =          bit32.lshift(1, 16)
 
 local NULL_ARRAY = table.freeze({}) :: Column
 local NULL = newproxy(false)
-local NULL_RECORD = table.freeze({ dense = 0 }) :: ecs_record_t
 
 local ECS_INTERNAL_ERROR = [[
 	This is an internal error, please file a bug report via the following link:
@@ -128,6 +127,12 @@ local ECS_INTERNAL_ERROR = [[
 	https://github.com/Ukendio/jecs/issues/new?template=BUG-REPORT.md
 ]]
 
+local function ecs_assert(condition, msg: string?)
+	if not condition then
+		error(msg)
+	end
+end
+
 local ecs_metadata: Map<i53, Map<i53, any>> = {}
 local ecs_max_component_id = 0
 local ecs_max_tag_id = EcsRest
@@ -287,6 +292,8 @@ local function ecs_get_alive(world, entity)
 	return current
 end
 
+local ECS_INTERNAL_ERROR_INCOMPATIBLE_ENTITY = "Entity is outside range"
+
 local function entity_index_new_id(entity_index: ecs_entity_index_t): i53
 	local dense_array = entity_index.dense_array
 	local alive_count = entity_index.alive_count
@@ -302,9 +309,8 @@ local function entity_index_new_id(entity_index: ecs_entity_index_t): i53
 
 	local id = max_id + 1
 	local range_end = entity_index.range_end
-	if range_end then
-		assert(id < range_end)
-	end
+	ecs_assert(range_end == nil or id < range_end, ECS_INTERNAL_ERROR_INCOMPATIBLE_ENTITY)
+
 	entity_index.max_id = id
 	alive_count += 1
 	entity_index.alive_count = alive_count
@@ -596,10 +602,10 @@ local function id_record_ensure(world: ecs_world_t, id: number): ecs_id_record_t
 	local is_pair = ECS_IS_PAIR(id)
 	if is_pair then
 		relation = entity_index_get_alive(entity_index, ECS_PAIR_FIRST(id)) :: i53
-		assert(relation and entity_index_is_alive(
+		ecs_assert(relation and entity_index_is_alive(
 			entity_index, relation), ECS_INTERNAL_ERROR)
 		target = entity_index_get_alive(entity_index, ECS_PAIR_SECOND(id)) :: i53
-		assert(target and entity_index_is_alive(
+		ecs_assert(target and entity_index_is_alive(
 			entity_index, target), ECS_INTERNAL_ERROR)
 	end
 
@@ -734,37 +740,31 @@ end
 
 local function world_range(world: ecs_world_t, range_begin: number, range_end: number?)
 	local entity_index = world.entity_index
-	if range_end then
-		range_end += 1
-	end
 
 	entity_index.range_begin = range_begin
 	entity_index.range_end = range_end
 
 	local max_id = entity_index.max_id
+
+	if range_begin > max_id then
 		local dense_array = entity_index.dense_array
 		local sparse_array = entity_index.sparse_array
 
-	if range_begin > max_id then
-		for i = max_id, range_begin - 1 do
-			dense_array[i] = 0
-			sparse_array[i] = NULL_RECORD
+		for i = max_id, range_begin do
+			dense_array[i] = i
+			sparse_array[i] = {
+				dense = 0
+			} :: ecs_record_t
 		end
-		sparse_array[range_begin] = { dense = 0 } :: ecs_record_t
+		entity_index.max_id = range_begin - 1
+		entity_index.alive_count = range_begin - 1
 	end
-
-	entity_index.max_id = range_begin
-	entity_index.alive_count = range_begin
 end
 
 local function world_entity(world: ecs_world_t, entity: i53?): i53
 	local entity_index = world.entity_index
 	if entity then
 		local index = ECS_ID(entity)
-		local range_begin = entity_index.range_begin
-		if range_begin then
-			assert(index > range_begin)
-		end
 		local max_id = entity_index.max_id
 		local sparse_array = entity_index.sparse_array
 		local dense_array = entity_index.dense_array
@@ -805,10 +805,6 @@ local function world_entity(world: ecs_world_t, entity: i53?): i53
 			dense_array[dense] = e_swap
 			return any
 		else
-			local range_end = entity_index.range_end
-			if range_end then
-				assert(index < range_end)
-			end
 			for i = max_id + 1, index do
 				sparse_array[i]	= { dense = i } :: ecs_record_t
 				dense_array[i] = i
@@ -2572,6 +2568,9 @@ export type World = {
 
 	observable: any,
 
+	--- Enforce a check on entities to be created within desired range
+	range: (self: World, range_begin: number, range_end: number?) -> (),
+
 	--- Creates a new entity
 	entity: (self: World, id: Entity?) -> Entity,
 	--- Creates a new entity located in the first 256 ids.

test/tests.luau

@@ -633,24 +633,30 @@ TEST("world:each()", function()
 	end
 end)
 
-TEST("world:entity()", function()
-	do CASE "range"
+TEST("world:range()", function()
+	do CASE ""
 		local world = jecs.world()
 		world = lifetime_tracker_add(world, {})
 		world:range(1000, 2000)
+		local e = world:entity()
+		CHECK(e == 1000)
 
 		world:entity(1590)
-		CHECK_EXPECT_ERR(function()
 
-			world:entity(5000)
-		end)
+		CHECK(world:entity(5000) == 5000)
 
 		CHECK(world:contains(1590))
 		world:set(591, jecs.Name, "9888")
 		CHECK(not world:contains(591))
-		CHECK(not world:contains(5000))
+		CHECK(world:contains(5000))
 		CHECK(not world:contains(988))
+
+		local e = world:entity(2000)
+		CHECK(e == 2000)
 	end
+end)
+
+TEST("world:entity()", function()
 	do CASE "desired id"
 		local world = jecs.world()
 		local id = world:entity()