From 6437bd3b549d9889cd9f5e2e2255fd68c7d4a69e Mon Sep 17 00:00:00 2001
From: "Zed A. Shaw" <zed.shaw@gmail.com>
Date: Sat, 28 Jun 2025 12:47:17 -0400
Subject: [PATCH] Now have a 'destroy' method that removes everything related
 to an entity. Closes #18.

---
 dinkyecs.hpp       | 28 ++++++++++++++++++++--------
 tests/dinkyecs.cpp |  6 ++++++
 2 files changed, 26 insertions(+), 8 deletions(-)

diff --git a/dinkyecs.hpp b/dinkyecs.hpp
index b29ed63..99bbb89 100644
--- a/dinkyecs.hpp
+++ b/dinkyecs.hpp
@@ -19,7 +19,6 @@ namespace DinkyECS
   template <typename T>
     struct ComponentStorage {
       std::vector<T> data;
-      std::queue<size_t> free_indices;
     };
 
   struct Event {
@@ -36,12 +35,23 @@ namespace DinkyECS
     std::unordered_map<std::type_index, std::any> $facts;
     std::unordered_map<std::type_index, EventQueue> $events;
     std::unordered_map<std::type_index, std::any> $component_storages;
+    std::unordered_map<std::type_index, std::queue<size_t>> $free_indices;
     std::unordered_map<Entity, bool> $constants;
 
     Entity entity() { return ++entity_count; }
 
     void destroy(DinkyECS::Entity entity) {
-      (void)entity;
+      dbc::check(!$constants.contains(entity), "trying to destroy an entity in constants");
+
+      for(auto& [tid, map] : $components) {
+
+        if(map.contains(entity)) {
+          size_t index = map.at(entity);
+          auto& free_queue = $free_indices.at(tid);
+          free_queue.push(index);
+          map.erase(entity);
+        }
+      }
     }
 
     void clone_into(DinkyECS::World &to_world) {
@@ -76,11 +86,12 @@ namespace DinkyECS
     template <typename Comp>
       size_t make_component() {
         auto &storage = component_storage_for<Comp>();
+        auto &free_queue = $free_indices.at(std::type_index(typeid(Comp)));
         size_t index;
 
-        if(!storage.free_indices.empty()) {
-          index = storage.free_indices.front();
-          storage.free_indices.pop();
+        if(!free_queue.empty()) {
+          index = free_queue.front();
+          free_queue.pop();
         } else {
           storage.data.emplace_back();
           index = storage.data.size() - 1;
@@ -93,6 +104,7 @@ namespace DinkyECS
       ComponentStorage<Comp> &component_storage_for() {
         auto type_index = std::type_index(typeid(Comp));
         $component_storages.try_emplace(type_index, ComponentStorage<Comp>{});
+        $free_indices.try_emplace(type_index, std::queue<size_t>{});
         return std::any_cast<ComponentStorage<Comp> &>(
             $component_storages.at(type_index));
       }
@@ -113,10 +125,10 @@ namespace DinkyECS
 
         if(map.contains(ent)) {
           size_t index = map.at(ent);
-          component_storage_for<Comp>().free_indices.push(index);
+          auto& free_queue = $free_indices.at(std::type_index(typeid(Comp)));
+          free_queue.push(index);
+          map.erase(ent);
         }
-
-        map.erase(ent);
       }
 
     template <typename Comp>
diff --git a/tests/dinkyecs.cpp b/tests/dinkyecs.cpp
index ccf6ba5..59d4978 100644
--- a/tests/dinkyecs.cpp
+++ b/tests/dinkyecs.cpp
@@ -199,4 +199,10 @@ TEST_CASE("can destroy all entity", "[ecs-destroy]") {
   world.set<Velocity>(entity, {10,10});
   world.set<Gravity>(entity, {1});
   world.set<Motion>(entity, {0,0});
+
+  world.destroy(entity);
+
+  REQUIRE(!world.has<Velocity>(entity));
+  REQUIRE(!world.has<Gravity>(entity));
+  REQUIRE(!world.has<Motion>(entity));
 }