Simplify event emissions

10 files changed, 82 insertions, 115 deletions

diff --git a/core/src/main/java/coffee/liz/ecs/ComponentCache.java b/core/src/main/java/coffee/liz/ecs/ComponentCache.java
index 70487d6..1e6788f 100644
--- a/core/src/main/java/coffee/liz/ecs/ComponentCache.java
+++ b/core/src/main/java/coffee/liz/ecs/ComponentCache.java
@@ -45,14 +45,9 @@ public final class ComponentCache {
      */
     public void onEntityEvent(final EntityEvent event) {
         switch (event) {
-            case ComponentAdded componentAdded:
-                addComponentEntry(componentAdded.getComponentClazz(), componentAdded.getEntity());
-                break;
-            case ComponentRemoved componentRemoved:
-                removeComponentEntry(componentRemoved.getComponentClazz(), componentRemoved.getEntity());
-                break;
-            default:
-                break;
+            case ComponentAdded a -> addComponentEntry(a.getComponentClazz(), a.getEntity());
+            case ComponentRemoved r -> removeComponentEntry(r.getComponentType(), r.getEntity());
+            default -> throw new IllegalStateException("Unexpected value: " + event);
         }
     }
 
@@ -116,6 +111,10 @@ public final class ComponentCache {
 
     private void removeComponentEntry(final Class<? extends Component> componentType, final Entity entity) {
         final Set<Entity> entities = entitiesByComponent.get(componentType);
+        if (entities == null) {
+            return;
+        }
+
         entities.remove(entity);
         if (entities.isEmpty()) {
             entitiesByComponent.remove(componentType);
diff --git a/core/src/main/java/coffee/liz/ecs/DAGWorld.java b/core/src/main/java/coffee/liz/ecs/DAGWorld.java
index a6a11db..0cc7d5d 100644
--- a/core/src/main/java/coffee/liz/ecs/DAGWorld.java
+++ b/core/src/main/java/coffee/liz/ecs/DAGWorld.java
@@ -1,10 +1,10 @@
 package coffee.liz.ecs;
 
 import coffee.liz.ecs.events.EntityEvent;
-import coffee.liz.ecs.events.Hook;
 import coffee.liz.ecs.model.Component;
 import coffee.liz.ecs.model.Entity;
 import coffee.liz.ecs.model.Query;
+import coffee.liz.ecs.model.QueryBuilder;
 import coffee.liz.ecs.model.System;
 import coffee.liz.ecs.model.World;
 
@@ -23,29 +23,20 @@ import java.util.Map;
 import java.util.Queue;
 import java.util.Set;
 import java.util.concurrent.atomic.AtomicInteger;
+import java.util.function.Consumer;
 import java.util.stream.Collectors;
 
 /** World that updates in {@link System#getDependencies()} topological order. */
 @Log4j2
 @RequiredArgsConstructor
 public class DAGWorld<T> implements World<T> {
-    /** All entities in the world. */
-    protected final Set<Entity> entities = Collections.synchronizedSet(new HashSet<>());
-
-    /** Incremental cache mapping component types to entities having that component. */
+    private final Set<Entity> entities = Collections.synchronizedSet(new HashSet<>());
     private final ComponentCache componentCache = new ComponentCache();
-
-    /** Shared world listener to keep cache synchronized with entity component changes. */
-    private final Hook<EntityEvent> cacheUpdateHook = componentCache::onEntityEvent;
-
-    /** Deterministic ID's for spawned entities. */
+    private final Consumer<EntityEvent> entityEventConsumer = componentCache::onEntityEvent;
     private final AtomicInteger nextEntityId = new AtomicInteger(0);
-
-    /** All registered systems. */
     protected final Map<Class<? extends System<T>>, System<T>> systems;
-
-    /** Ordered list of systems for execution. */
     private final List<System<T>> systemExecutionOrder;
+    private final QueryBuilder<T> queryBuilder = new QueryBuilder<>(this);
 
     @SafeVarargs
     public DAGWorld(final System<T>... systems) {
@@ -57,7 +48,7 @@ public class DAGWorld<T> implements World<T> {
     @Override
     public Entity createEntity() {
         final Entity entity = Entity.builder().id(nextEntityId.incrementAndGet()).build();
-        entity.subscribe(cacheUpdateHook);
+        entity.subscribe(entityEventConsumer);
         entities.add(entity);
         componentCache.addEntity(entity);
         return entity;
@@ -65,7 +56,7 @@ public class DAGWorld<T> implements World<T> {
 
     @Override
     public void removeEntity(final Entity entity) {
-        entity.unsubscribe(cacheUpdateHook);
+        entity.unsubscribe(entityEventConsumer);
         componentCache.removeEntity(entity);
         entities.remove(entity);
     }
@@ -81,6 +72,11 @@ public class DAGWorld<T> implements World<T> {
     }
 
     @Override
+    public QueryBuilder<T> queryable() {
+        return queryBuilder;
+    }
+
+    @Override
     public void update(final T state, final float deltaSeconds) {
         systemExecutionOrder.forEach(system -> system.update(this, state, deltaSeconds));
     }
@@ -93,7 +89,7 @@ public class DAGWorld<T> implements World<T> {
 
     private Set<Entity> resolveAllOf(final Set<Class<? extends Component>> components) {
         if (components.isEmpty()) {
-            return Set.copyOf(entities);
+            return entities;
         }
         return componentCache.entitiesMatchingAllOf(components);
     }
@@ -110,7 +106,7 @@ public class DAGWorld<T> implements World<T> {
 
     private Set<Entity> resolveNoneOf(final Set<Class<? extends Component>> components) {
         if (components.isEmpty()) {
-            return Set.copyOf(entities);
+            return entities;
         }
 
         final Set<Entity> excluded = new HashSet<>();
@@ -181,7 +177,7 @@ public class DAGWorld<T> implements World<T> {
         for (final System<T> system : systemExecutionOrder) {
             system.dispose();
         }
-        entities.forEach(entity -> entity.unsubscribe(cacheUpdateHook));
+        entities.forEach(entity -> entity.unsubscribe(entityEventConsumer));
         componentCache.clear();
         entities.clear();
     }
diff --git a/core/src/main/java/coffee/liz/ecs/events/ComponentRemoved.java b/core/src/main/java/coffee/liz/ecs/events/ComponentRemoved.java
index 25047b6..b9ef853 100644
--- a/core/src/main/java/coffee/liz/ecs/events/ComponentRemoved.java
+++ b/core/src/main/java/coffee/liz/ecs/events/ComponentRemoved.java
@@ -10,12 +10,12 @@ import lombok.RequiredArgsConstructor;
  *
  * @param entity
  *            entity that lost a component
- * @param componentClazz
+ * @param componentType
  *            class key of the component that was removed
  */
 @RequiredArgsConstructor
 @Getter
 public class ComponentRemoved implements EntityEvent {
     private final Entity entity;
-    private final Class<? extends Component> componentClazz;
+    private final Class<? extends Component> componentType;
 }
diff --git a/core/src/main/java/coffee/liz/ecs/events/EventBus.java b/core/src/main/java/coffee/liz/ecs/events/EventBus.java
new file mode 100644
index 0000000..d814281
--- /dev/null
+++ b/core/src/main/java/coffee/liz/ecs/events/EventBus.java
@@ -0,0 +1,49 @@
+package coffee.liz.ecs.events;
+
+import java.util.Set;
+import java.util.concurrent.CopyOnWriteArraySet;
+import java.util.function.Consumer;
+
+/**
+ * Minimal observable contract for event emission.
+ *
+ * @param <E>
+ *            emitted event type
+ */
+public class EventBus<E> {
+    protected final Set<Consumer<E>> subscriptions = new CopyOnWriteArraySet<>();
+
+    /**
+     * Register a hook to receive future events.
+     *
+     * @param hook
+     *            callback to invoke for each emitted event
+     * @return subscribed hook.
+     */
+    public Consumer<E> subscribe(final Consumer<E> hook) {
+        subscriptions.add(hook);
+        return hook;
+    }
+
+    /**
+     * Remove a previously registered hook.
+     *
+     * @param hook
+     *            callback to remove
+     * @return true
+     *            if the hook was removed.
+     */
+    public boolean unsubscribe(final Consumer<E> hook) {
+        return subscriptions.remove(hook);
+    }
+
+    /**
+     * Publish an event to all currently subscribed hooks.
+     *
+     * @param event
+     *            event to publish
+     */
+    public void emit(final E event) {
+        subscriptions.forEach(s -> s.accept(event));
+    }
+}
diff --git a/core/src/main/java/coffee/liz/ecs/events/Hook.java b/core/src/main/java/coffee/liz/ecs/events/Hook.java
deleted file mode 100644
index 8f91aad..0000000
--- a/core/src/main/java/coffee/liz/ecs/events/Hook.java
+++ /dev/null
@@ -1,13 +0,0 @@
-package coffee.liz.ecs.events;
-
-import java.util.function.Consumer;
-
-/**
- * Event callback used by {@link Observable}.
- *
- * @param <E>
- *            consumed event type
- */
-@FunctionalInterface
-public interface Hook<E> extends Consumer<E> {
-}
diff --git a/core/src/main/java/coffee/liz/ecs/events/Observable.java b/core/src/main/java/coffee/liz/ecs/events/Observable.java
deleted file mode 100644
index d849407..0000000
--- a/core/src/main/java/coffee/liz/ecs/events/Observable.java
+++ /dev/null
@@ -1,34 +0,0 @@
-package coffee.liz.ecs.events;
-
-/**
- * Minimal observable contract for event emission.
- *
- * @param <E>
- *            emitted event type
- */
-public interface Observable<E> {
-    /**
-     * Register a hook to receive future events.
-     *
-     * @param hook
-     *            callback to invoke for each emitted event
-     * @return the registered hook
-     */
-    Hook<E> subscribe(Hook<E> hook);
-
-    /**
-     * Remove a previously registered hook.
-     *
-     * @param hook
-     *            callback to remove
-     */
-    void unsubscribe(Hook<E> hook);
-
-    /**
-     * Publish an event to all currently subscribed hooks.
-     *
-     * @param event
-     *            event to publish
-     */
-    void emit(E event);
-}
diff --git a/core/src/main/java/coffee/liz/ecs/math/Vec2f.java b/core/src/main/java/coffee/liz/ecs/math/Vec2f.java
index 42b73e7..4bd0529 100644
--- a/core/src/main/java/coffee/liz/ecs/math/Vec2f.java
+++ b/core/src/main/java/coffee/liz/ecs/math/Vec2f.java
@@ -3,7 +3,7 @@ package coffee.liz.ecs.math;
 import static java.lang.Math.sqrt;
 
 import lombok.Builder;
-import lombok.Data;
+import lombok.EqualsAndHashCode;
 import lombok.Getter;
 import lombok.RequiredArgsConstructor;
 
@@ -12,8 +12,8 @@ import java.util.function.Function;
 /** Float impl of {@link Vec2}. */
 @Getter
 @RequiredArgsConstructor
-@Data
 @Builder
+@EqualsAndHashCode
 public final class Vec2f implements Vec2<Float> {
     /** X coordinate. */
     private final Float x;
diff --git a/core/src/main/java/coffee/liz/ecs/math/Vec2i.java b/core/src/main/java/coffee/liz/ecs/math/Vec2i.java
index 326a5df..0e612ec 100644
--- a/core/src/main/java/coffee/liz/ecs/math/Vec2i.java
+++ b/core/src/main/java/coffee/liz/ecs/math/Vec2i.java
@@ -3,7 +3,7 @@ package coffee.liz.ecs.math;
 import static java.lang.Math.sqrt;
 
 import lombok.Builder;
-import lombok.Data;
+import lombok.EqualsAndHashCode;
 import lombok.Getter;
 import lombok.RequiredArgsConstructor;
 
@@ -13,7 +13,7 @@ import java.util.function.Function;
 @Getter
 @RequiredArgsConstructor
 @Builder
-@Data
+@EqualsAndHashCode
 public final class Vec2i implements Vec2<Integer> {
     /** X coordinate. */
     private final Integer x;
diff --git a/core/src/main/java/coffee/liz/ecs/model/Entity.java b/core/src/main/java/coffee/liz/ecs/model/Entity.java
index 4984d5d..bbd417e 100644
--- a/core/src/main/java/coffee/liz/ecs/model/Entity.java
+++ b/core/src/main/java/coffee/liz/ecs/model/Entity.java
@@ -3,20 +3,16 @@ package coffee.liz.ecs.model;
 import coffee.liz.ecs.events.ComponentAdded;
 import coffee.liz.ecs.events.ComponentRemoved;
 import coffee.liz.ecs.events.EntityEvent;
-import coffee.liz.ecs.events.Hook;
-import coffee.liz.ecs.events.Observable;
+import coffee.liz.ecs.events.EventBus;
 
 import lombok.AllArgsConstructor;
 import lombok.Builder;
-import lombok.Data;
 import lombok.Getter;
 import lombok.RequiredArgsConstructor;
 
-import java.util.ArrayList;
 import java.util.Collection;
 import java.util.Collections;
 import java.util.HashMap;
-import java.util.IdentityHashMap;
 import java.util.Map;
 import java.util.Set;
 
@@ -24,19 +20,12 @@ import java.util.Set;
 @Builder
 @RequiredArgsConstructor
 @AllArgsConstructor
-@Data
-public class Entity implements Observable<EntityEvent> {
-    /** Unique id. */
+public class Entity extends EventBus<EntityEvent> {
     private final int id;
 
-    /** Instances of {@link Component}s. */
     @Builder.Default
     private Map<Class<? extends Component>, Component> componentMap = Collections.synchronizedMap(new HashMap<>());
 
-    @Builder.Default
-    /** Event subscribers for entity mutation events. */
-    private transient Set<Hook<EntityEvent>> hooks = Collections.newSetFromMap(new IdentityHashMap<>());
-
     /**
      * Check if entity has component type.
      *
@@ -89,8 +78,9 @@ public class Entity implements Observable<EntityEvent> {
      */
     public <C extends Component> Entity add(final C component) {
         final Class<? extends Component> componentType = component.getKey();
-        componentMap.put(componentType, component);
-        emit(new ComponentAdded(this, componentType));
+        if (componentMap.put(componentType, component) == null) {
+            emit(new ComponentAdded(this, componentType));
+        }
         return this;
     }
 
@@ -118,23 +108,4 @@ public class Entity implements Observable<EntityEvent> {
     public Set<Class<? extends Component>> componentTypes() {
         return componentMap.keySet();
     }
-
-    /** Subscribe to component mutation events emitted by this entity. */
-    @Override
-    public Hook<EntityEvent> subscribe(final Hook<EntityEvent> hook) {
-        hooks.add(hook);
-        return hook;
-    }
-
-    /** Remove a previously subscribed mutation hook. */
-    @Override
-    public void unsubscribe(final Hook<EntityEvent> hook) {
-        hooks.remove(hook);
-    }
-
-    /** Emit a mutation event to all current subscribers. */
-    @Override
-    public void emit(final EntityEvent event) {
-        new ArrayList<>(hooks).forEach(hook -> hook.accept(event));
-    }
 }
diff --git a/core/src/main/java/coffee/liz/ecs/model/System.java b/core/src/main/java/coffee/liz/ecs/model/System.java
index c00334a..f16cdba 100644
--- a/core/src/main/java/coffee/liz/ecs/model/System.java
+++ b/core/src/main/java/coffee/liz/ecs/model/System.java
@@ -1,6 +1,5 @@
 package coffee.liz.ecs.model;
 
-import java.time.Duration;
 import java.util.Collection;
 
 /**