Add basic scene graph API

Sources/FirebladeECS/Entity.swift

@@ -101,6 +101,12 @@ public struct Entity {
     public func destroy() {
         nexus.destroy(entity: self)
     }
+
+    public func addChild(_ entity: Entity) {
+    }
+
+    public func removeChild(_ entity: Entity) {
+    }
 }
 
 // MARK: - Equatable

Sources/FirebladeECS/Family.swift

@@ -40,6 +40,14 @@ public struct Family<R> where R: FamilyRequirementsManaging {
     }
 }
 
+// MARK: - Equatable
+extension Family: Equatable {
+    public static func == (lhs: Family<R>, rhs: Family<R>) -> Bool {
+        return lhs.nexus == rhs.nexus &&
+            lhs.traits == rhs.traits
+    }
+}
+
 extension Family: Sequence {
     __consuming public func makeIterator() -> ComponentsIterator {
         return ComponentsIterator(family: self)
@@ -123,10 +131,30 @@ extension Family {
 
 extension Family.EntityComponentIterator: LazySequenceProtocol { }
 
-// MARK: - Equatable
-extension Family: Equatable {
-    public static func == (lhs: Family<R>, rhs: Family<R>) -> Bool {
-        return lhs.nexus == rhs.nexus &&
-            lhs.traits == rhs.traits
+// MARK: - relatives iterator
+
+extension Family {
+    @inlinable public var descendRelatives: RelativesIterator {
+        return RelativesIterator(family: self)
+    }
+
+    public struct RelativesIterator: IteratorProtocol {
+        @usableFromInline var memberIdsIterator: UnorderedSparseSetIterator<EntityIdentifier>
+        @usableFromInline unowned let nexus: Nexus
+
+        public init(family: Family<R>) {
+            self.nexus = family.nexus
+            memberIdsIterator = family.memberIds.makeIterator()
+        }
+
+        public mutating func next() -> R.RelativesDescending? {
+            guard let parentId = memberIdsIterator.next() else {
+                return nil
+            }
+
+            fatalError("implement")
+        }
     }
 }
+
+extension Family.RelativesIterator: LazySequenceProtocol { }

Sources/FirebladeECS/Family1.swift

@@ -24,6 +24,12 @@ public struct Requires1<A>: FamilyRequirementsManaging where A: Component {
         let compA: A = nexus.get(unsafeComponentFor: entityId)
         return (entity, compA)
     }
+
+    public static func relativesDescending(nexus: Nexus, parentId: EntityIdentifier, childId: EntityIdentifier) -> (parent: A, child: A) {
+        let parentCompA: A = nexus.get(unsafeComponentFor: parentId)
+        let childCompA: A = nexus.get(unsafeComponentFor: childId)
+        return (parent: parentCompA, child: childCompA)
+    }
 }
 
 extension Nexus {

Sources/FirebladeECS/Family2.swift

@@ -5,6 +5,8 @@
 //  Created by Christian Treffs on 21.08.19.
 //
 
+// swiftlint:disable large_tuple
+
 public typealias Family2<A: Component, B: Component> = Family<Requires2<A, B>>
 
 public struct Requires2<A, B>: FamilyRequirementsManaging where A: Component, B: Component {
@@ -19,13 +21,20 @@ public struct Requires2<A, B>: FamilyRequirementsManaging where A: Component, B:
         return (compA, compB)
     }
 
-    // swiftlint:disable:next large_tuple
     public static func entityAndComponents(nexus: Nexus, entityId: EntityIdentifier) -> (Entity, A, B) {
         let entity: Entity = nexus.get(unsafeEntity: entityId)
         let compA: A = nexus.get(unsafeComponentFor: entityId)
         let compB: B = nexus.get(unsafeComponentFor: entityId)
         return (entity, compA, compB)
     }
+
+    public static func relativesDescending(nexus: Nexus, parentId: EntityIdentifier, childId: EntityIdentifier) -> (parent: (A, B), child: (A, B)) {
+        let pcA: A = nexus.get(unsafeComponentFor: parentId)
+        let pcB: B = nexus.get(unsafeComponentFor: parentId)
+        let ccA: A = nexus.get(unsafeComponentFor: childId)
+        let ccB: B = nexus.get(unsafeComponentFor: childId)
+        return (parent: (pcA, pcB), child: (ccA, ccB))
+    }
 }
 
 extension Nexus {

Sources/FirebladeECS/Family3.swift

@@ -30,6 +30,16 @@ public struct Requires3<A, B, C>: FamilyRequirementsManaging where A: Component,
         let compC: C = nexus.get(unsafeComponentFor: entityId)
         return (entity, compA, compB, compC)
     }
+    public static func relativesDescending(nexus: Nexus, parentId: EntityIdentifier, childId: EntityIdentifier) ->
+        (parent: (A, B, C), child: (A, B, C)) {
+            let pcA: A = nexus.get(unsafeComponentFor: parentId)
+            let pcB: B = nexus.get(unsafeComponentFor: parentId)
+            let pcC: C = nexus.get(unsafeComponentFor: parentId)
+            let ccA: A = nexus.get(unsafeComponentFor: childId)
+            let ccB: B = nexus.get(unsafeComponentFor: childId)
+            let ccC: C = nexus.get(unsafeComponentFor: childId)
+            return (parent: (pcA, pcB, pcC), child: (ccA, ccB, ccC))
+    }
 }
 
 extension Nexus {

Sources/FirebladeECS/Family4.swift

@@ -32,6 +32,19 @@ public struct Requires4<A, B, C, D>: FamilyRequirementsManaging where A: Compone
         let compD: D = nexus.get(unsafeComponentFor: entityId)
         return (entity, compA, compB, compC, compD)
     }
+
+    public static func relativesDescending(nexus: Nexus, parentId: EntityIdentifier, childId: EntityIdentifier) ->
+        (parent: (A, B, C, D), child: (A, B, C, D)) {
+            let pcA: A = nexus.get(unsafeComponentFor: parentId)
+            let pcB: B = nexus.get(unsafeComponentFor: parentId)
+            let pcC: C = nexus.get(unsafeComponentFor: parentId)
+            let pcD: D = nexus.get(unsafeComponentFor: parentId)
+            let ccA: A = nexus.get(unsafeComponentFor: childId)
+            let ccB: B = nexus.get(unsafeComponentFor: childId)
+            let ccC: C = nexus.get(unsafeComponentFor: childId)
+            let ccD: D = nexus.get(unsafeComponentFor: childId)
+            return (parent: (pcA, pcB, pcC, pcD), child: (ccA, ccB, ccC, ccD))
+    }
 }
 
 extension Nexus {

Sources/FirebladeECS/Family5.swift

@@ -34,6 +34,22 @@ public struct Requires5<A, B, C, D, E>: FamilyRequirementsManaging where A: Comp
         let compE: E = nexus.get(unsafeComponentFor: entityId)
         return (entity, compA, compB, compC, compD, compE)
     }
+
+    public static func relativesDescending(nexus: Nexus, parentId: EntityIdentifier, childId: EntityIdentifier) ->
+        (parent: (A, B, C, D, E), child: (A, B, C, D, E)) {
+            let pcA: A = nexus.get(unsafeComponentFor: parentId)
+            let pcB: B = nexus.get(unsafeComponentFor: parentId)
+            let pcC: C = nexus.get(unsafeComponentFor: parentId)
+            let pcD: D = nexus.get(unsafeComponentFor: parentId)
+            let pcE: E = nexus.get(unsafeComponentFor: parentId)
+            let ccA: A = nexus.get(unsafeComponentFor: childId)
+            let ccB: B = nexus.get(unsafeComponentFor: childId)
+            let ccC: C = nexus.get(unsafeComponentFor: childId)
+            let ccD: D = nexus.get(unsafeComponentFor: childId)
+            let ccE: E = nexus.get(unsafeComponentFor: childId)
+            return (parent: (pcA, pcB, pcC, pcD, pcE),
+                    child: (ccA, ccB, ccC, ccD, ccE))
+    }
 }
 
 extension Nexus {

Sources/FirebladeECS/FamilyRequirementsManaging.swift

@@ -9,6 +9,7 @@ public protocol FamilyRequirementsManaging {
     associatedtype Components
     associatedtype ComponentTypes
     associatedtype EntityAndComponents
+    associatedtype RelativesDescending
 
     init(_ types: ComponentTypes)
 
@@ -16,4 +17,5 @@ public protocol FamilyRequirementsManaging {
 
     static func components(nexus: Nexus, entityId: EntityIdentifier) -> Components
     static func entityAndComponents(nexus: Nexus, entityId: EntityIdentifier) -> EntityAndComponents
+    static func relativesDescending(nexus: Nexus, parentId: EntityIdentifier, childId: EntityIdentifier) -> RelativesDescending
 }

Tests/FirebladeECSTests/SceneGraphTests.swift

@@ -0,0 +1,56 @@
+//
+//  SceneGraphTests.swift
+//  FirebladeECSTests
+//
+//  Created by Christian Treffs on 30.09.19.
+//
+
+import XCTest
+import FirebladeECS
+
+class SceneGraphTests: XCTestCase {
+
+    var nexus: Nexus!
+    
+    override func setUp() {
+        super.setUp()
+        nexus = Nexus()
+    }
+
+    override func tearDown() {
+        super.tearDown()
+        nexus = nil
+    }
+
+    func testParent() {
+        let nttParrent = nexus.createEntity(with: Position(x: 1, y: 1))
+    
+        let nttChild1 = nexus.createEntity(with: Position(x: 2, y: 2))
+        let nttChild2 = nexus.createEntity(with: Position(x: 3, y: 3))
+    
+        nttParrent.addChild(nttChild1)
+        nttParrent.removeChild(nttChild1)
+        nttParrent.addChild(nttChild1)
+        
+        let family = nexus.family(requires: Position.self)
+        
+        
+        family
+            .descendRelatives.forEach { (parent: Position, child: Position) in
+                
+        }
+        
+        let family2 = nexus.family(requiresAll: Position.self, Name.self)
+        
+        family2
+            .descendRelatives
+            .forEach { (parent, child) in
+                let (pPos, pName) = parent
+                let (cPos, cName) = child
+                
+                
+            }
+        
+    }
+
+}