Undo split out column layout (#472)

Author: mlange-42

CHANGELOG.md

@@ -1,6 +1,10 @@
 # Changelog
 
-## [[unpublished]](https://github.com/mlange-42/ark/compare/v0.7.0...main)
+## [[v0.7.1]](https://github.com/mlange-42/ark/compare/v0.7.0...v0.7.1)
+
+### Bugfixes
+
+- Fixes non-nil component retrieved from mapper (#472, fixes #470, rolls back #430)
 
 ### Other
 

benchmark/table/main.go

@@ -10,7 +10,7 @@ import (
 	"github.com/mlange-42/ark/benchmark"
 )
 
-const version = "v0.7.1-dev"
+const version = "v0.7.1"
 const goVersion = "1.25.4"
 
 func main() {

ecs/column.go

@@ -7,18 +7,14 @@ import (
 
 // column storage for components in an table.
 type column struct {
-	columnLayout
-	data       reflect.Value // data buffer
-	elemType   reflect.Type  // element type of the column
-	target     Entity        // target entity if for a relation component
-	index      uint32        // index of the column in the containing table
-	isRelation bool          // whether this column is for a relation component
-	isTrivial  bool          // Whether the column's type is trivial , i.e. without pointers.
-}
-
-type columnLayout struct {
-	pointer  unsafe.Pointer // pointer to the first element
-	itemSize uintptr        // memory size of items
+	data       reflect.Value  // data buffer
+	pointer    unsafe.Pointer // pointer to the first element
+	itemSize   uintptr        // memory size of items
+	elemType   reflect.Type   // element type of the column
+	target     Entity         // target entity if for a relation component
+	index      uint32         // index of the column in the containing table
+	isRelation bool           // whether this column is for a relation component
+	isTrivial  bool           // Whether the column's type is trivial , i.e. without pointers.
 }
 
 // newColumn creates a new column for a given type and capacity.
@@ -28,10 +24,8 @@ func newColumn(index uint32, tp reflect.Type, itemSize uintptr, isRelation bool,
 	pointer := data.Addr().UnsafePointer()
 
 	return column{
-		columnLayout: columnLayout{
-			pointer:  pointer,
-			itemSize: itemSize,
-		},
+		pointer:    pointer,
+		itemSize:   itemSize,
 		target:     target,
 		index:      index,
 		data:       data,
@@ -42,7 +36,7 @@ func newColumn(index uint32, tp reflect.Type, itemSize uintptr, isRelation bool,
 }
 
 // Get returns a pointer to the component at the given index.
-func (c *columnLayout) Get(index uintptr) unsafe.Pointer {
+func (c *column) Get(index uintptr) unsafe.Pointer {
 	return unsafe.Add(c.pointer, index*c.itemSize)
 }
 

ecs/internal/generate/maps.go.template

@@ -270,8 +270,9 @@ func (m *Map{{.}}{{$genericsShort}}) Set(entity Entity, {{$args}}) {
 	{{- end}}
 
 	index := &m.world.storage.entities[entity.id]
+	row := uintptr(index.row)
 	{{- range $i, $v := $upper}}
-	set(m.storage{{$v}}, index, {{index $lower $i}})
+	*(*{{$v}})(m.storage{{$v}}.columns[index.table].Get(row)) = *{{index $lower $i}}
 	{{- end}}
 
 	if m.world.storage.observers.HasObservers(OnSetComponents) {

ecs/internal/generate/observers.go.template

@@ -121,10 +121,11 @@ func (o *Observer{{.}}{{$genericsShort}}) Register(w *World) *Observer{{.}}{{$ge
 	{{- end}}
 	o.observer.callback = func(e Entity) {
 		index := &w.storage.entities[e.id]
+		row := uintptr(index.row)
 		o.callback(
 			e,
 			{{- range $i, $v := $upper}}
-			get[{{$v}}](storage{{$v}}, index),
+			(*{{$v}})(storage{{$v}}.columns[index.table].Get(row)),
 			{{- end}}
 		)
 	}

ecs/map.go

@@ -225,7 +225,7 @@ func (m *Map[T]) Set(entity Entity, comp *T) {
 	m.world.storage.checkHasComponent(entity, m.ids[0])
 
 	index := &m.world.storage.entities[entity.id]
-	set(m.storage, index, comp)
+	*(*T)(m.storage.columns[index.table].Get(uintptr(index.row))) = *comp
 
 	if m.world.storage.observers.HasObservers(OnSetComponents) {
 		newMask := &m.world.storage.archetypes[m.world.storage.tables[index.table].archetype].mask

ecs/map_test.go

@@ -384,6 +384,44 @@ func TestMapAddRelationBatch(t *testing.T) {
 	expectEqual(t, n, cnt)
 }
 
+func TestMapGetReturnsNilForMissingComponentIssue470(t *testing.T) {
+	world := NewWorld()
+	posMap := NewMap[Position](world)
+	velMap := NewMap[Velocity](world)
+
+	entity := posMap.NewEntity(&Position{X: 10, Y: 20})
+	if !posMap.Has(entity) {
+		t.Fatal("Entity should have Position component")
+	}
+	if velMap.Has(entity) {
+		t.Fatal("Entity should NOT have Velocity component")
+	}
+
+	vel := velMap.Get(entity)
+	if vel != nil {
+		t.Fatal("Velocity component should be nil")
+	}
+}
+
+func TestMap1GetReturnsNilForMissingComponentIssue470(t *testing.T) {
+	world := NewWorld()
+	posMap := NewMap1[Position](world)
+	velMap := NewMap1[Velocity](world)
+
+	entity := posMap.NewEntity(&Position{X: 10, Y: 20})
+	if !posMap.HasAll(entity) {
+		t.Fatal("Entity should have Position component")
+	}
+	if velMap.HasAll(entity) {
+		t.Fatal("Entity should NOT have Velocity component")
+	}
+
+	vel := velMap.Get(entity)
+	if vel != nil {
+		t.Fatal("Velocity component should be nil")
+	}
+}
+
 func BenchmarkMap1Get_1000(b *testing.B) {
 	w := NewWorld()
 	mapper := NewMap1[Position](w)