From ef04f7aec7752268b9a86a5f46d991c7c69648e9 Mon Sep 17 00:00:00 2001
From: Adrian Papari <a@onedaybeard.net>
Date: Sun, 8 Nov 2015 22:40:41 +0100
Subject: [PATCH]  Fixes #390: limit ComponentMappers to one per component type
 per world.

---
 .../main/java/com/artemis/ComponentManager.java    | 14 ++++++++++++--
 artemis/src/main/java/com/artemis/World.java       |  2 +-
 .../test/java/com/artemis/ComponentMapperTest.java | 10 ++++++++++
 3 files changed, 23 insertions(+), 3 deletions(-)

diff --git a/artemis/src/main/java/com/artemis/ComponentManager.java b/artemis/src/main/java/com/artemis/ComponentManager.java
index 47f91d787..7daa75285 100644
--- a/artemis/src/main/java/com/artemis/ComponentManager.java
+++ b/artemis/src/main/java/com/artemis/ComponentManager.java
@@ -35,6 +35,8 @@ public class ComponentManager extends BaseSystem {
 	private final ComponentPool pooledComponents;
 	
 	private int highestSeenEntityId;
+
+	private Bag<ComponentMapper> componentMappers = new Bag<ComponentMapper>();
 	
 	protected final ComponentTypeFactory typeFactory;
 
@@ -150,8 +152,7 @@ private void ensurePackedComponentCapacity(int entityId) {
 		}
 	}
 
-	protected BitSet getPackedComponentOwners(ComponentType type)
-	{
+	protected BitSet getPackedComponentOwners(ComponentType type) {
 		BitSet owners = packedComponentOwners.safeGet(type.getIndex());
 		if (owners == null) {
 			owners = new BitSet();
@@ -160,6 +161,15 @@ protected BitSet getPackedComponentOwners(ComponentType type)
 		return owners;
 	}
 
+	<T extends Component> ComponentMapper<T> getMapper(Class<T> mapper) {
+		int index = typeFactory.getIndexFor(mapper);
+		if (componentMappers.safeGet(index) == null) {
+			componentMappers.set(index, ComponentMapper.getFor(mapper, world));
+		}
+
+		return componentMappers.get(index);
+	}
+
 	@SuppressWarnings("unchecked")
 	<T extends Component> T newInstance(Class<T> componentClass, boolean constructorHasWorldParameter) {
 		try {
diff --git a/artemis/src/main/java/com/artemis/World.java b/artemis/src/main/java/com/artemis/World.java
index c08b7b184..6866367f4 100644
--- a/artemis/src/main/java/com/artemis/World.java
+++ b/artemis/src/main/java/com/artemis/World.java
@@ -432,7 +432,7 @@ void updateEntityStates() {
 	 * @return mapper for specified component type
 	 */
 	public <T extends Component> ComponentMapper<T> getMapper(Class<T> type) {
-		return BasicComponentMapper.getFor(type, this);
+		return cm.getMapper(type);
 	}
 
 	/**
diff --git a/artemis/src/test/java/com/artemis/ComponentMapperTest.java b/artemis/src/test/java/com/artemis/ComponentMapperTest.java
index 9b4135fdd..9184712b6 100644
--- a/artemis/src/test/java/com/artemis/ComponentMapperTest.java
+++ b/artemis/src/test/java/com/artemis/ComponentMapperTest.java
@@ -49,6 +49,16 @@ protected void process(Entity e) {
 		createAndProcessWorld(new TestSystemA());
 	}
 
+	@Test
+	public void mappers_are_per_type_per_world() {
+		World w1 = new World();
+		World w2 = new World();
+
+		assertNotSame(w1.getMapper(ComponentX.class), w2.getMapper(ComponentX.class));
+		assertNotSame(w1.getMapper(ComponentX.class), w1.getMapper(ComponentY.class));
+		assertSame(w1.getMapper(ComponentX.class), w1.getMapper(ComponentX.class));
+	}
+
 	@Test
 	public void create_if_exists_should_recycle_existing_component() {