Switched to using a new Entity class

While likely less performant, it should provide good readability,
and good explaination of how an entity is related in the engine

javaecs/src/main/java/nz/ac/massey/javaecs/ComponentArray.java

@@ -24,15 +24,15 @@ class ComponentArray{
     // The object data array
     private List<Object> componentArray = new ArrayList<>();
     // The mappings between data and entity
-    private Map<Integer, Integer> entityComponentDataMap = new HashMap<>();
+    private Map<Entity, Integer> entityComponentDataMap = new HashMap<>();
-    private Map<Integer, Integer> componentDataEntityMap = new HashMap<>();
+    private Map<Integer, Entity> componentDataEntityMap = new HashMap<>();
 
     /**
      * Gets the data Object associated with the entity.
      * @param entity the entity to find data for
      * @return the Object if the data exists, else null
      */
-    protected Object getData(int entity){
+    protected Object getData(Entity entity){
         try{
             return componentArray.get(entityComponentDataMap.get(entity));
         }
@@ -52,7 +52,7 @@ class ComponentArray{
      * @param component the component data
      * @return true if successful, false if the entity is already subscribed to the component
      */
-    protected boolean insertData(int entity, Object component){
+    protected boolean insertData(Entity entity, Object component){
         if (entityComponentDataMap.containsKey(entity)){
             ECS.writeErr("Entity is already subscribed to the component");
             return false;
@@ -71,7 +71,7 @@ class ComponentArray{
      * @param destinationEntity
      * @return 0 if successful, -1 if the object is null, -2 if a NullPointerException occurred, and -3 if inserting data failed
      */
-    protected int moveData(int sourceEntity, int destinationEntity){
+    protected int moveData(Entity sourceEntity, Entity destinationEntity){
         try{
             Object data = entityComponentDataMap.get(sourceEntity);
             if (data == null) return -1;
@@ -92,7 +92,7 @@ class ComponentArray{
      * @param entity the entity to remove the data from
      * @return true if the data was removed. If the data isn't found then returns false
      */
-    protected boolean removeData(int entity){
+    protected boolean removeData(Entity entity){
         if (!entityComponentDataMap.containsKey(entity)){
             ECS.writeErr("Attempted to remove non-existent entity");
             return false;
@@ -102,7 +102,7 @@ class ComponentArray{
         // Replace the removed component with the last component in the array
         componentArray.set(removedComponentDataIndex, componentArray.get(componentArray.size() -1));
         // update the data positions in the map
-        int lastEntity = componentDataEntityMap.get(componentArray.size()-1);
+        Entity lastEntity = componentDataEntityMap.get(componentArray.size()-1);
         entityComponentDataMap.replace(lastEntity, removedComponentDataIndex);
         componentDataEntityMap.replace(removedComponentDataIndex, lastEntity);
         // Finally, remomve the last elements

javaecs/src/main/java/nz/ac/massey/javaecs/ComponentManager.java

@@ -24,7 +24,7 @@ class ComponentManager{
      * @param componentData the component data to associate
      * @param entity the entity to associate data to
      */
-    protected boolean addComponentToEntity(Type componentType, Object componentData, int entity){
+    protected boolean addComponentToEntity(Type componentType, Object componentData, Entity entity){
         return componentArrays.get(componentType).insertData(entity, componentData);
     }
 
@@ -32,7 +32,7 @@ class ComponentManager{
      * Signals to the ComponentManager the entity was destroyed. All component data references should be removed.
      * @param entity the entity that was destroyed.
      */
-    public void entityDestroyed(int entity){
+    public void entityDestroyed(Entity entity){
         for (Type key : componentArrays.keySet()) {
             componentArrays.get(key).removeData(entity);
         }
@@ -44,7 +44,7 @@ class ComponentManager{
      * @param entity the entity to find data for
      * @return the Object data found, or null if it was not found
      */
-    public Object getComponent(Type componentType, int entity){
+    public Object getComponent(Type componentType, Entity entity){
         return componentArrays.get(componentType).getData(entity);
     }
 
@@ -83,7 +83,7 @@ class ComponentManager{
      * @param component the component class type to consider 
      * @return true if the component was moved successfully, else false
      */
-    protected boolean moveComponentData(int sourceEntity, int destinationEntity, Type component){
+    protected boolean moveComponentData(Entity sourceEntity, Entity destinationEntity, Type component){
         if (componentArrays.get(component).moveData(sourceEntity, destinationEntity) == 0){
             return true;
         }
@@ -96,7 +96,7 @@ class ComponentManager{
      * @param destinationEntity the entity to move data to
      * @param sourceRegistrations the component registrations of the source entity
      */
-    protected void moveAllComponentData(int sourceEntity, int destinationEntity, BitSet sourceRegistrations){
+    protected void moveAllComponentData(Entity sourceEntity, Entity destinationEntity, BitSet sourceRegistrations){
         int result = sourceRegistrations.nextSetBit(0);
         while (result != -1){
             Type key = indexComponentType.get(result);
@@ -126,7 +126,7 @@ class ComponentManager{
      * @param componentType the class type of the component to remove
      * @param entity the entity to remove the component from
      */
-    public boolean removeComponentFromEntity(Type componentType, int entity){
+    public boolean removeComponentFromEntity(Type componentType, Entity entity){
         return componentArrays.get(componentType).removeData(entity);
     }
 }

javaecs/src/main/java/nz/ac/massey/javaecs/ECS.java

@@ -56,9 +56,9 @@ public class ECS {
      * @return the index of the new entity
      * @throws IndexOutOfBoundsException
      */
-    Integer createEntity() throws IndexOutOfBoundsException{
+    Entity createEntity() throws IndexOutOfBoundsException{
-        int newEntity = entityManager.addEntity();
+        Entity newEntity = entityManager.addEntity();
-        if (newEntity == -1) throw new IndexOutOfBoundsException("Could not create a new entity");
+        if (newEntity == null) throw new IndexOutOfBoundsException("Could not create a new entity");
         return newEntity;
     }
 
@@ -75,7 +75,7 @@ public class ECS {
      * Signals each manager to remove the specified entity
      * @param entity the entity to destroy
      */
-    void destroyEntity(int entity){
+    void destroyEntity(Entity entity){
         entityManager.removeEntity(entity);
         componentManager.entityDestroyed(entity);
         systemManager.entityDestroyed(entity);
@@ -99,7 +99,7 @@ public class ECS {
      * @param componentName the class name of the component to add
      * @param component the actual component data
      */
-    boolean addComponent(int entity, Type componentName, Object component){
+    boolean addComponent(Entity entity, Type componentName, Object component){
         if (entityManager.registerComponent(componentManager.getComponentIndex(componentName), entity))
         {
             systemManager.entityRegistrationsChanged(entity, entityManager.getRegistrations(entity));
@@ -114,7 +114,7 @@ public class ECS {
      * @param entity the entity to remove the component from
      * @param componentName the class name of the component
      */
-    boolean removeComponent(int entity, Type componentType){
+    boolean removeComponent(Entity entity, Type componentType){
         if (entityManager.unregisterComponent(componentManager.getComponentIndex(componentType), entity))
         {
             componentManager.removeComponentFromEntity(componentType, entity);
@@ -131,7 +131,7 @@ public class ECS {
      * @param componentType the class type of the component
      * @return the component data Object associated with the entity
      */
-    Object getComponentData(int entity, Type componentType){
+    Object getComponentData(Entity entity, Type componentType){
         return componentManager.getComponent(componentType, entity);
     }
 

javaecs/src/main/java/nz/ac/massey/javaecs/ECSSystem.java

@@ -16,7 +16,7 @@ import java.util.Set;
 import java.util.HashSet;
 
 abstract class ECSSystem{
-    Set<Integer> entities = new HashSet<>();
+    Set<Entity> entities = new HashSet<>();
 
     /**
      * Implement additional parameterised init() functions as required.

javaecs/src/main/java/nz/ac/massey/javaecs/Entity.java

@@ -0,0 +1,38 @@
+package nz.ac.massey.javaecs;
+/**
+ * Entity class. 
+ * Whilst an entity is just an Integer, and using Integer values
+ * would be more performant (no function call), it is encapsulated to help
+ * distinguish between entities and Integers.
+ */
+public class Entity {
+    private int value;
+
+    public Entity(int value){
+        this.value = value;
+    }
+
+    public int getValue() {
+        return value;
+    }
+
+    /**
+     * Returns the int value wrapped as an entity.
+     * Used to provide a distinction between creating a new entity, and
+     * using an int value we assume is a valid entity.
+     * 
+     * Functionally, this is no different to creating a new entity.
+     * 
+     * @param value
+     * @return
+     */
+    public static Entity asEntity(int value){
+        return new Entity(value);
+    }
+
+    @Override
+    public boolean equals(Object obj) 
+    {
+      return (this.getValue() == ((Entity)obj).getValue());
+    }
+}

javaecs/src/main/java/nz/ac/massey/javaecs/EntityManager.java

@@ -21,7 +21,7 @@ import java.util.ArrayList;
  * I.e. Controls adding and removing entities, and registration and deregistration of components.
  */
 class EntityManager{
-    private Queue<Integer> unusedEntities;
+    private Queue<Entity> unusedEntities;
     private List<BitSet> entityRegistrations;
     private int maxSize = 1024;
 
@@ -33,7 +33,7 @@ class EntityManager{
         entityRegistrations = new ArrayList<>();
 
         for (int i = 0; i < maxSize; i++) {
-            unusedEntities.add(i);
+            unusedEntities.add(new Entity(i));
             entityRegistrations.add(null); // Leave bitsets out as if they are null the entity isn't initialised properly
         }
     }
@@ -48,7 +48,7 @@ class EntityManager{
         entityRegistrations = new ArrayList<>();
         
         for (int i = 0; i < maxEntities; i++) {
-            unusedEntities.add(i);
+            unusedEntities.add(new Entity(i));
             entityRegistrations.add(null);
         }
     }
@@ -57,13 +57,13 @@ class EntityManager{
      * Creates a new entity
      * @return the index of the new entity, or -1 if there is no more available entities
      */
-    protected Integer addEntity(){
+    protected Entity addEntity(){
         if (unusedEntities.size() == 0){
             ECS.writeErr("No available space to create a new entity");
-            return -1;
+            return null;
         }
-        int result = unusedEntities.remove();
+        Entity result = unusedEntities.remove();
-        entityRegistrations.set(result, new BitSet());
+        entityRegistrations.set(result.getValue(), new BitSet());
         return result;
     }
 
@@ -80,12 +80,12 @@ class EntityManager{
      * @param entity the entity whose BitSet to retrieve
      * @return the BitSet of the provided entity
      */
-    protected BitSet getRegistrations(int entity){
+    protected BitSet getRegistrations(Entity entity){
         try{
-            return entityRegistrations.get(entity);
+            return entityRegistrations.get(entity.getValue());
         }
         catch (IndexOutOfBoundsException e){
-            ECS.writeErr("Index out of bounds error getting registrations for " + entity + ";\nThe entity might not exist");
+            ECS.writeErr("Index out of bounds error getting registrations for " + entity.getValue() + ";\nThe entity might not exist");
             return new BitSet(); // Using a blank BitSet will retain data safety (that is, no data will be modified)
         }
     }
@@ -96,18 +96,18 @@ class EntityManager{
      * @param entity the entity to register
      * @return true if the operation was successful
      */
-    protected boolean registerComponent(int component, int entity){
+    protected boolean registerComponent(int component, Entity entity){
-        if (entity >= maxSize){
+        if (entity.getValue() >= maxSize){
-            ECS.writeErr("Attempted to assign a component to non-existent entity: " + entity);
+            ECS.writeErr("Attempted to assign a component to non-existent entity: " + entity.getValue());
             return false;
         }
-        else if (entityRegistrations.get(entity).get(component))
+        else if (entityRegistrations.get(entity.getValue()).get(component))
         {
             ECS.writeErr("Entity is already assigned to the component");
             return false;
         }
         else{
-            entityRegistrations.get(entity).set(component);
+            entityRegistrations.get(entity.getValue()).set(component);
             return true;
         }
     }
@@ -118,9 +118,9 @@ class EntityManager{
      * <b>Does not handle associated data</b> Use the method in ECS to remove entities cleanly
      * @param entity the entity to remove
      */
-    protected void removeEntity(int entity){
+    protected void removeEntity(Entity entity){
         unusedEntities.add(entity);
-        entityRegistrations.set(entity, null);
+        entityRegistrations.set(entity.getValue(), null);
     }
 
     /**
@@ -128,8 +128,8 @@ class EntityManager{
      * @param entity the entity to set
      * @param registrations the preset registrations
      */
-    protected void setRegistrations(int entity, BitSet registrations){
+    protected void setRegistrations(Entity entity, BitSet registrations){
-        entityRegistrations.set(entity, registrations);
+        entityRegistrations.set(entity.getValue(), registrations);
     }
 
     /**
@@ -140,9 +140,9 @@ class EntityManager{
      * @param entity the entity to remove
      * @return true if successful
      */
-    protected boolean unregisterComponent(int component, int entity){
+    protected boolean unregisterComponent(int component, Entity entity){
         try{
-            entityRegistrations.get(entity).clear(component);
+            entityRegistrations.get(entity.getValue()).clear(component);
             return true;
         }
         catch (NullPointerException e){
@@ -175,16 +175,17 @@ class EntityManager{
             // Consistency should be maintained.
             // This is computationally expensive; we must re-order every assigned entity above newSize, if the newSize is smaller
             if (newSize < maxSize){
-                List<Integer> outOfBounds = new ArrayList<>();
+                List<Entity> outOfBounds = new ArrayList<>();
                 for (int i = newSize; i < maxSize; i++) {
-                    if (!unusedEntities.remove(i)){
+                    Entity entityI = Entity.asEntity(i);
+                    if (!unusedEntities.remove(entityI)){
                         // Could not remove element, as it didn't exist (already assigned).
                         // must find it and reassign it a new in-bounds value
-                        outOfBounds.add(i);
+                        outOfBounds.add(entityI);
                     }
                 }
-                for (Integer integer : outOfBounds) {
+                for (Entity integer : outOfBounds) {
-                    int newPos = addEntity();
+                    Entity newPos = addEntity();
                     setRegistrations(newPos, getRegistrations(integer));
                     // Invoke an update in the SystemManager
                     systemManager.entityDestroyed(integer);
@@ -200,7 +201,7 @@ class EntityManager{
             else{
                 // Init unassigned values
                 for (int i = maxSize; i < newSize; i++) {
-                    unusedEntities.add(i);
+                    unusedEntities.add(new Entity(i));
                     entityRegistrations.add(new BitSet());
                 }
             }

javaecs/src/main/java/nz/ac/massey/javaecs/SystemManager.java

@@ -23,7 +23,7 @@ class SystemManager{
      * Removes the entity from each system's tracked entities
      * @param entity the destroyed entity
      */
-    protected void entityDestroyed(int entity){
+    protected void entityDestroyed(Entity entity){
         for (Type key : systems.keySet()) {
             systems.get(key).entities.remove(entity);
         }
@@ -35,7 +35,7 @@ class SystemManager{
      * @param entity the entity that was modified
      * @param entityRegistrations the new registrations of the entity
      */
-    protected void entityRegistrationsChanged(int entity, BitSet entityRegistrations){
+    protected void entityRegistrationsChanged(Entity entity, BitSet entityRegistrations){
         for (Type key : systems.keySet()) {
             // Check if the signature is null
             if (!entityRegistrations.equals(null)){

javaecs/src/test/java/nz/ac/massey/javaecs/AppTest.java

@@ -33,7 +33,7 @@ class AppTest {
     class TestSystem extends ECSSystem{
         public void init(){}
         public void update() {
-            for (Integer entity : entities) {
+            for (Entity entity : entities) {
                 TestObject entityComponent = (TestObject)gameEngine.getComponentData(entity, TestObject.class);
                 entityComponent.i++;
             }
@@ -44,7 +44,7 @@ class AppTest {
      */
     @Test
     void testAssignOne() {
-        int entity = gameEngine.createEntity();
+        Entity entity = gameEngine.createEntity();
         gameEngine.addComponent(entity, TestObject.class, new TestObject());
         assertEquals(1, ((TestObject)gameEngine.getComponentData(entity, TestObject.class)).i);
     }
@@ -55,7 +55,7 @@ class AppTest {
     @Test
     void testAssignMax(){
         for (int i = 0; i < gameEngine.getMaxEntities(); i++) {
-            int entity = gameEngine.createEntity();
+            Entity entity = gameEngine.createEntity();
             gameEngine.addComponent(entity, TestObject.class, new TestObject());
             assertEquals(1, ((TestObject)gameEngine.getComponentData(entity, TestObject.class)).i);
         }
@@ -72,7 +72,7 @@ class AppTest {
                 });
             }
             else{
-                int entity = gameEngine.createEntity();
+                Entity entity = gameEngine.createEntity();
                 gameEngine.addComponent(entity, TestObject.class, new TestObject());
             }
         }
@@ -83,7 +83,7 @@ class AppTest {
      */
     @Test
     void testRemoveOne(){
-        int entity = gameEngine.createEntity();
+        Entity entity = gameEngine.createEntity();
         gameEngine.addComponent(entity, TestObject.class, new TestObject());
         gameEngine.destroyEntity(entity);
         assertNull(((TestObject)gameEngine.getComponentData(entity, TestObject.class)));
@@ -94,7 +94,7 @@ class AppTest {
      */
     @Test
     void testRunSystem(){
-        int entity = gameEngine.createEntity();
+        Entity entity = gameEngine.createEntity();
         gameEngine.addComponent(entity, TestObject.class, new TestObject());
 
         for (int i = 0; i < 5; i++) {
@@ -110,7 +110,7 @@ class AppTest {
      */
     @Test
     void testResizeMinimal(){
-        int entity = gameEngine.createEntity();
+        Entity entity = gameEngine.createEntity();
         gameEngine.addComponent(entity, TestObject.class, new TestObject());
 
         gameEngine.resizeMaximum(10);
@@ -124,12 +124,12 @@ class AppTest {
     @Test
     void testLargeCreateDelete(){
         for (int i = 0; i < gameEngine.getMaxEntities(); i++) {
-            int entity = gameEngine.createEntity();
+            Entity entity = gameEngine.createEntity();
             gameEngine.addComponent(entity, TestObject.class, new TestObject());
             assertEquals(1, ((TestObject)gameEngine.getComponentData(entity, TestObject.class)).i);
         }
         for (int i = 256; i < 512; i++) {
-            gameEngine.destroyEntity(i);
+            gameEngine.destroyEntity(Entity.asEntity(i));
         }
     }
 
@@ -139,12 +139,12 @@ class AppTest {
     @Test
     void testLargeCreateDeleteResize(){
         for (int i = 0; i < gameEngine.getMaxEntities(); i++) {
-            int entity = gameEngine.createEntity();
+            Entity entity = gameEngine.createEntity();
             gameEngine.addComponent(entity, TestObject.class, new TestObject());
             assertEquals(1, ((TestObject)gameEngine.getComponentData(entity, TestObject.class)).i);
         }
         for (int i = 256; i < 512; i++) {
-            gameEngine.destroyEntity(i);
+            gameEngine.destroyEntity(Entity.asEntity(i));
         }
 
         gameEngine.resizeMaximum(1024 - 255);
@@ -156,12 +156,12 @@ class AppTest {
     @Test
     void testLargeCreateDeleteResizeTooSmall(){
         for (int i = 0; i < gameEngine.getMaxEntities(); i++) {
-            int entity = gameEngine.createEntity();
+            Entity entity = gameEngine.createEntity();
             gameEngine.addComponent(entity, TestObject.class, new TestObject());
             assertEquals(1, ((TestObject)gameEngine.getComponentData(entity, TestObject.class)).i);
         }
         for (int i = 256; i < 512; i++) {
-            gameEngine.destroyEntity(i);
+            gameEngine.destroyEntity(Entity.asEntity(i));
         }
         assertFalse(gameEngine.resizeMaximum(512));
         
@@ -175,12 +175,12 @@ class AppTest {
 
     @Test
     void testAssignToNonExistentEntity(){
-        assertFalse(gameEngine.addComponent(1025, TestObject.class, new TestObject()));
+        assertFalse(gameEngine.addComponent(Entity.asEntity(1025), TestObject.class, new TestObject()));
     }
 
     @Test
     void testRemoveComponent(){
-        int entity = gameEngine.createEntity();
+        Entity entity = gameEngine.createEntity();
         gameEngine.addComponent(entity, TestObject.class, new TestObject());
         gameEngine.removeComponent(entity, TestObject.class);
         assertFalse(gameEngine.entityManager.getRegistrations(entity).get(gameEngine.getComponentIndex(TestObject.class)));
@@ -214,12 +214,12 @@ class AppTest {
 
     @Test
     void testRemoveNonExistentComponentData(){
-        assertFalse(gameEngine.removeComponent(1, TestObject.class));
+        assertFalse(gameEngine.removeComponent(Entity.asEntity(1), TestObject.class));
     }
 
     @Test
     void testAssignComponentAlreadyAssigned(){
-        int entity = gameEngine.createEntity();
+        Entity entity = gameEngine.createEntity();
         gameEngine.addComponent(entity, TestObject.class, new TestObject());
         assertFalse(gameEngine.addComponent(entity, TestObject.class, new TestObject()));
     }