feat: destruction dependency

app/ecs/ecs.js

@@ -23,7 +23,7 @@ export default class Ecs {
 
   deferredChanges = {}
 
-  destroying = new Set();
+  $$destructionDependencies = new Map();
 
   diff = {};
 
@@ -42,6 +42,20 @@ export default class Ecs {
     }
   }
 
+  addDestructionDependency(id, promise) {
+    if (!this.$$destructionDependencies.has(id)) {
+      this.$$destructionDependencies.set(id, new Set())
+    }
+    const dependencies = this.$$destructionDependencies.get(id);
+    dependencies.add(promise);
+    promise.then(() => {
+      dependencies.delete(promise);
+      if (0 === dependencies.size) {
+        this.$$destructionDependencies.delete(id);
+      }
+    });
+  }
+
   async apply(patch) {
     const creating = [];
     const destroying = [];
@@ -213,7 +227,10 @@ export default class Ecs {
   }
 
   destroy(entityId) {
-    this.destroying.add(entityId);
+    if (!this.$$destructionDependencies.has(entityId)) {
+      this.$$destructionDependencies.set(entityId, new Set())
+    }
+    this.$$destructionDependencies.get(entityId).add(0);
   }
 
   destroyImmediately(entityId) {
@@ -444,9 +461,17 @@ export default class Ecs {
         System.elapsed -= System.frequency;
       }
     }
-    if (this.destroying.size > 0) {
-      this.destroyMany(this.destroying);
-      this.destroying.clear();
+    const destroying = new Set();
+    for (const [id, dependencies] of this.$$destructionDependencies) {
+      if (1 === dependencies.size && dependencies.has(0)) {
+        destroying.add(id);
+      }
+    }
+    if (destroying.size > 0) {
+      this.destroyMany(destroying);
+      for (const id of destroying) {
+        this.$$destructionDependencies.delete(id);
+      }
     }
   }