Add components function builder implementation

Sources/FirebladeECS/Nexus+ComponentsBuilder.swift

@@ -0,0 +1,47 @@
+//
+//  Nexus+ComponentsBuilder.swift
+//
+//
+//  Created by Christian Treffs on 30.07.20.
+//
+
+#if swift(<5.3)
+@_functionBuilder
+public enum ComponentsBuilderPreview { }
+public typealias ComponentsBuilder = ComponentsBuilderPreview
+#else
+@functionBuilder
+public enum ComponentsBuilder { }
+#endif
+
+extension ComponentsBuilder {
+    public static func buildBlock(_ components: Component...) -> [Component] {
+        components
+    }
+
+    public struct Context {
+        public let index: Int
+    }
+}
+
+extension Nexus {
+    @discardableResult
+    public func createEntity(@ComponentsBuilder using componentBuilder: () -> Component) -> Entity {
+        self.createEntity(with: componentBuilder())
+    }
+
+    @discardableResult
+    public func createEntity(@ComponentsBuilder using componentBuilder: () -> [Component]) -> Entity {
+        self.createEntity(with: componentBuilder())
+    }
+
+    @discardableResult
+    public func createEntities(count: Int, @ComponentsBuilder using componentBuilder: (ComponentsBuilder.Context) -> Component) -> [Entity] {
+        (0..<count).map { self.createEntity(with: componentBuilder(ComponentsBuilder.Context(index: $0))) }
+    }
+
+    @discardableResult
+    public func createEntities(count: Int, @ComponentsBuilder using componentBuilder: (ComponentsBuilder.Context) -> [Component]) -> [Entity] {
+        (0..<count).map { self.createEntity(with: componentBuilder(ComponentsBuilder.Context(index: $0))) }
+    }
+}