Merge pull request #6 from chrisbenincasa/downcast-component

Return downcasted Component type from Entity

.gitignore

@@ -1,2 +1,4 @@
 target/
 *.swp
+
+.idea/

crane-examples/src/main/scala/Example.scala

@@ -37,8 +37,8 @@ object Example extends App {
       // val entities = world.getEntitiesWithExclusions(include=List(classOf[Position], classOf[Velocity]), exclude=List(classOf[Useless]))
 
       entities.foreach{ entity: Entity =>
-          val position = entity.getComponent(classOf[Position])
-          val velocity = entity.getComponent(classOf[Velocity])
+          val position = entity.getComponent[Position]
+          val velocity = entity.getComponent[Velocity]
 
           (position, velocity) match {
             case(Some(p: Position), Some(v: Velocity)) =>
@@ -54,8 +54,8 @@ object Example extends App {
   // Equivalent to the system above, except you specify each individual entity
   class MovementEntityProcessingSystem extends EntityProcessingSystem(include=List(classOf[Position], classOf[Velocity])) {
     override def processEntity(e: Entity, delta: Int) {
-      val position = e.getComponent(classOf[Position])
-      val velocity = e.getComponent(classOf[Velocity])
+      val position = e.getComponent[Position]
+      val velocity = e.getComponent[Velocity]
 
       (position, velocity) match {
         case(Some(p: Position), Some(v: Velocity)) =>

crane/src/main/scala/crane/Entity.scala

@@ -6,6 +6,8 @@ package crane
 /** Crane Exception Imports **/
 import crane.exceptions.{DeadEntityException, DuplicateTagException, MissingComponentException}
 
+import scala.reflect.ClassTag
+
 /** External Imports **/
 import scala.collection.mutable.ArrayBuffer
 
@@ -41,13 +43,15 @@ class Entity(var tag: String = "", val components: ArrayBuffer[Component] = Arra
   // Accessors
   def world: Option[World] = _world
 
-  /** Returns component of a classOf[Component]
-   *
-   * @param componentType the component to get (the class, not the instance)
+  /**
+   * Returns component of a classOf[Component]
    */
-  def getComponent[T <: AnyRef](componentType: T): Option[Component] = {
+  def getComponent[T <: Component : ClassTag]: Option[T] = {
     if (alive) {
-      components find { case(component) => component.getClass == componentType }
+      components find {
+        case component: T => true
+        case _ => false
+      } map (_.asInstanceOf[T])
     } else {
       throw new DeadEntityException
     }
@@ -71,11 +75,10 @@ class Entity(var tag: String = "", val components: ArrayBuffer[Component] = Arra
 
   /** Removes component of a classOf[Component]
    *
-   * @param componentType the component to remove (the class, not the instance)
    */
-  def removeComponent[T <: AnyRef](componentType: T) {
+  def removeComponent[T <: Component : ClassTag]() {
     if (alive) {
-      val removeEntity: Option[Component] = getComponent(componentType)
+      val removeEntity: Option[Component] = getComponent[T]
       removeEntity match {
         case Some(e: Component) =>
           components -= e

crane/src/test/scala/crane/EntitySpec.scala

@@ -17,14 +17,24 @@ class EntitySpec extends FlatSpec with MockFactory {
     entity.components += component
     assert(entity.components.length == 1)
 
-    assert(entity.getComponent(component.getClass) match {
+    assert(entity.getComponent[Component] match {
       case Some(s) => true
       case _ => false
     })
+  }
+
+  it should "downcast Component when getting it from entity" in {
+    val entity = Entity()
+    class CustomComponent extends Component
+    val customComponent = mock[CustomComponent]
+
+    entity.components.append(customComponent)
 
-    assert(entity.getComponent(classOf[Component]) match {
-      case Some(s) => false
-      case _ => true
+    assert(entity.components.length == 1)
+
+    assert(entity.getComponent[CustomComponent] match {
+      case Some(cc: CustomComponent) => true
+      case _ => false
     })
   }
 
@@ -51,7 +61,7 @@ class EntitySpec extends FlatSpec with MockFactory {
     }
 
     intercept[DeadEntityException] {
-      entity.removeComponent(classOf[Component])
+      entity.removeComponent[Component]
     }
   }
 }