Add exclusive relationship

jecs.luau

@@ -1,3 +1,4 @@
+
 --!optimize 2
 --!native
 --!strict
@@ -186,9 +187,10 @@ local ECS_ENTITY_MASK =       bit32.lshift(1, 24)
 local ECS_GENERATION_MASK =   bit32.lshift(1, 16)
 local ECS_PAIR_OFFSET = 	                 2^48
 
-local ECS_ID_DELETE =                 	     0b01
+local ECS_ID_DELETE =                 	     0b0001
-local ECS_ID_IS_TAG =                 	     0b10
+local ECS_ID_IS_TAG =                 	     0b0010
-local ECS_ID_MASK =                   	     0b00
+local ECS_ID_IS_EXCLUSIVE =                  0b0100
+local ECS_ID_MASK =                   	     0b0000
 
 local HI_COMPONENT_ID =                       256
 local EcsOnAdd =             HI_COMPONENT_ID +  1
@@ -204,7 +206,8 @@ local EcsRemove =            HI_COMPONENT_ID + 10
 local EcsName =              HI_COMPONENT_ID + 11
 local EcsOnArchetypeCreate = HI_COMPONENT_ID + 12
 local EcsOnArchetypeDelete = HI_COMPONENT_ID + 13
-local EcsRest =              HI_COMPONENT_ID + 14
+local EcsExclusive =         HI_COMPONENT_ID + 14
+local EcsRest =              HI_COMPONENT_ID + 15
 
 local NULL_ARRAY = table.freeze({}) :: Column
 local NULL = newproxy(false)
@@ -673,6 +676,7 @@ local function id_record_ensure(world: World, id: Entity): ComponentRecord
 	local is_pair = ECS_IS_PAIR(id :: number)
 
 	local has_delete = false
+	local is_exclusive = false
 
 	if is_pair then
 		relation = entity_index_get_alive(entity_index, ECS_PAIR_FIRST(id :: number)) :: i53
@@ -687,6 +691,10 @@ local function id_record_ensure(world: World, id: Entity): ComponentRecord
 		if cleanup_policy_target == EcsDelete then
 			has_delete = true
 		end
+
+		if world_has_one_inline(world, relation, EcsExclusive) then
+			is_exclusive = true
+		end
 	else
 		local cleanup_policy = world_target(world, relation, EcsOnDelete, 0)
 
@@ -708,7 +716,8 @@ local function id_record_ensure(world: World, id: Entity): ComponentRecord
 	flags = bit32.bor(
 		flags,
 		if has_delete then ECS_ID_DELETE else 0,
-		if is_tag then ECS_ID_IS_TAG else 0
+		if is_tag then ECS_ID_IS_TAG else 0,
+		if is_exclusive then ECS_ID_IS_EXCLUSIVE else 0
 	)
 
 	idr = {
@@ -919,9 +928,20 @@ end
 
 local function find_archetype_with(world: World, id: Id, from: Archetype): Archetype
 	local id_types = from.types
+	local dst = table.clone(id_types)
+
+	if ECS_IS_PAIR(id::number) then
+		local first = ECS_PAIR_FIRST(id::number)
+		local idr = world.component_index[ECS_PAIR(first, EcsWildcard)]
+		if idr and bit32.btest(idr.flags, EcsExclusive) then
+			local cr = idr.records[from.id]
+			dst[cr] = id
+			return archetype_ensure(world, dst)
+		end
+	end
 
 	local at = find_insert(id_types :: { number } , id :: number)
-	local dst = table.clone(id_types)
+
 	table.insert(dst, at, id)
 
 	return archetype_ensure(world, dst)
@@ -2903,6 +2923,7 @@ return {
 	Delete = (EcsDelete :: any) :: Entity,
 	Remove = (EcsRemove :: any) :: Entity,
 	Name = (EcsName :: any) :: Entity<string>,
+	Exclusive = EcsExclusive :: Entity,
 	Rest = (EcsRest :: any) :: Entity,
 
 	pair = (ECS_PAIR :: any) :: <P, O>(first: Id<P>, second: Id<O>) -> Pair<P, O>,

test/tests.luau

@@ -24,9 +24,22 @@ type Id<T=unknown> = jecs.Id<T>
 local entity_visualiser = require("@tools/entity_visualiser")
 local dwi = entity_visualiser.stringify
 
-TEST("repro", function()
+FOCUS()
+TEST("exclusive", function()
+	local world = jecs.world()
+	local A = world:component()
+	world:add(A, jecs.Exclusive)
 
+	local B = world:component()
+	local C = world:component()
 
+	local e = world:entity()
+	world:add(e, pair(A, B))
+	world:add(e, pair(A, C))
+
+	CHECK(world:has(e, pair(A, B)) == false)
+	CHECK(world:has(e, pair(A, C)) == true)
+	-- print(jecs.entity_index_try_get(world.entity_index, e).archetype.type)
 end)
 
 TEST("bulk", function()