dummy systems

ecs.hpp

@@ -13,6 +13,7 @@
 #include <tuple>
 #include <mutex>
 #include <memory>
+#include <vector>
 #include <limits>
 #include <utility>
 #include <exception>
@@ -31,6 +32,7 @@
 namespace ecs_hpp
 {
     class entity;
+    class system;
     class registry;
 
     using family_id = std::uint16_t;
@@ -275,6 +277,21 @@ namespace std
     };
 }
 
+// -----------------------------------------------------------------------------
+//
+// system
+//
+// -----------------------------------------------------------------------------
+
+namespace ecs_hpp
+{
+    class system {
+    public:
+        virtual ~system() = default;
+        virtual void process(registry& owner) = 0;
+    };
+}
+
 // -----------------------------------------------------------------------------
 //
 // registry
@@ -285,8 +302,8 @@ namespace ecs_hpp
 {
     class registry final {
     public:
-        registry();
-        ~registry() noexcept;
+        registry() = default;
+        ~registry() noexcept = default;
 
         entity create_entity();
         bool destroy_entity(const entity& ent);
@@ -332,6 +349,10 @@ namespace ecs_hpp
         void for_joined_components(F&& f);
         template < typename... Ts, typename F >
         void for_joined_components(F&& f) const;
+
+        template < typename T, typename... Args >
+        void add_system(Args&&... args);
+        void process_systems();
     private:
         template < typename T >
         detail::component_storage<T>* find_storage_() noexcept;
@@ -370,6 +391,9 @@ namespace ecs_hpp
 
         using storage_uptr = std::unique_ptr<detail::component_storage_base>;
         std::unordered_map<family_id, storage_uptr> storages_;
+
+        using system_uptr = std::unique_ptr<system>;
+        std::vector<system_uptr> systems_;
     };
 }
 
@@ -483,9 +507,6 @@ namespace ecs_hpp
 
 namespace ecs_hpp
 {
-    inline registry::registry() = default;
-    inline registry::~registry() noexcept = default;
-
     inline entity registry::create_entity() {
         std::lock_guard<std::mutex> guard(mutex_);
         assert(last_entity_id_ < std::numeric_limits<entity_id>::max());
@@ -628,6 +649,19 @@ namespace ecs_hpp
         for_joined_components_impl_<Ts...>(std::forward<F>(f));
     }
 
+    template < typename T, typename... Args >
+    void registry::add_system(Args&&... args) {
+        std::lock_guard<std::mutex> guard(mutex_);
+        systems_.emplace_back(
+            std::make_unique<T>(std::forward<Args>(args)...));
+    }
+
+    inline void registry::process_systems() {
+        for ( auto& s : systems_ ) {
+            s->process(*this);
+        }
+    }
+
     template < typename T >
     detail::component_storage<T>* registry::find_storage_() noexcept {
         const auto family = detail::type_family<T>::id();

ecs_tests.cpp

@@ -318,7 +318,6 @@ TEST_CASE("registry") {
             }
         }
     }
-
     SECTION("for_joined_components") {
         {
             ecs::registry w;
@@ -365,4 +364,38 @@ TEST_CASE("registry") {
             }
         }
     }
+    SECTION("systems") {
+        {
+            class movement_system : public ecs::system {
+            public:
+                void process(ecs::registry& owner) override {
+                    owner.for_joined_components<position_c, velocity_c>([](
+                        ecs::entity e, position_c& p, const velocity_c& v)
+                    {
+                        p.x += v.x;
+                        p.y += v.y;
+                    });
+                }
+            };
+
+            ecs::registry w;
+            w.add_system<movement_system>();
+
+            auto e1 = w.create_entity();
+            auto e2 = w.create_entity();
+
+            e1.assign_component<position_c>(1, 2);
+            e1.assign_component<velocity_c>(3, 4);
+            e2.assign_component<position_c>(5, 6);
+            e2.assign_component<velocity_c>(7, 8);
+
+            w.process_systems();
+
+            REQUIRE(e1.get_component<position_c>().x == 1 + 3);
+            REQUIRE(e1.get_component<position_c>().y == 2 + 4);
+
+            REQUIRE(e2.get_component<position_c>().x == 5 + 7);
+            REQUIRE(e2.get_component<position_c>().y == 6 + 8);
+        }
+    }
 }