Make node.GerArchetype more idiomatic

ecs/archetype_node.go

@@ -98,11 +98,12 @@ func (a *archNode) Archetypes() archetypes {
 // GetArchetype returns the archetype for the given relation target.
 //
 // The target is ignored if the node has no relation component.
-func (a *archNode) GetArchetype(target Entity) *archetype {
+func (a *archNode) GetArchetype(target Entity) (*archetype, bool) {
 	if a.HasRelation {
-		return a.archetypeMap[target]
+		arch, ok := a.archetypeMap[target]
+		return arch, ok
 	}
-	return a.archetype
+	return a.archetype, a.archetype != nil
 }
 
 // SetArchetype sets the archetype for a node without a relation.

ecs/archetype_test.go

@@ -130,8 +130,9 @@ func TestArchetypeExtendLayouts(t *testing.T) {
 
 	node = newArchNode(All(id(0), id(1)), &nodeData{}, id(2), true, 8, comps)
 	node.CreateArchetype(16, entity)
-	arch2 := node.GetArchetype(entity)
+	arch2, ok := node.GetArchetype(entity)
 
+	assert.True(t, ok)
 	assert.Equal(t, len(arch2.layouts), 16)
 	node.ExtendArchetypeLayouts(16)
 	assert.Equal(t, len(arch2.layouts), 16)

ecs/world_internal.go

@@ -729,8 +729,8 @@ func (w *World) setRelation(entity Entity, comp ID, target Entity) {
 		return
 	}
 
-	arch := oldArch.node.GetArchetype(target)
-	if arch == nil {
+	arch, ok := oldArch.node.GetArchetype(target)
+	if !ok {
 		arch = w.createArchetype(oldArch.node, target, true)
 	}
 
@@ -824,8 +824,8 @@ func (w *World) setRelationArch(oldArch *archetype, oldArchLen uint32, comp ID,
 
 	oldIDs := oldArch.Components()
 
-	arch := oldArch.node.GetArchetype(target)
-	if arch == nil {
+	arch, ok := oldArch.node.GetArchetype(target)
+	if !ok {
 		arch = w.createArchetype(oldArch.node, target, true)
 	}
 
@@ -955,8 +955,8 @@ func (w *World) findOrCreateArchetype(start *archetype, add []ID, rem []ID, targ
 			curr = next
 		}
 	}
-	arch := curr.GetArchetype(target)
-	if arch == nil {
+	arch, ok := curr.GetArchetype(target)
+	if !ok {
 		arch = w.createArchetype(curr, target, true)
 	}
 	return arch