refactor(ecs): make systems own component signatures

include/EcoSimEngine/system/AISystem.hpp

@@ -7,10 +7,18 @@
 #include "EcoSimEngine/math/Vec2.hpp"
 #include "EcoSimEngine/system/System.hpp"
 #include "EcoSimEngine/utils/Random.hpp"
+#include "EcoSimEngine/component/ComponentIndices.hpp"
 
 class AISystem : public System
 {
 public:
+    static Signature requiredSignature() {
+        Signature signature;
+        signature.set(COMP_INDEX_CBehavior);
+        signature.set(COMP_INDEX_CTransform);
+        return signature;
+    }
+
     void update(
         EntityManager &em,
         ComponentManager &cm, 

include/EcoSimEngine/system/MetabolismSystem.hpp

@@ -5,10 +5,18 @@
 
 #include "EcoSimEngine/ecs/EntityManager.hpp"
 #include "EcoSimEngine/system/System.hpp"
+#include "EcoSimEngine/component/ComponentIndices.hpp"
 
 class MetabolismSystem : public System
 {
 public:
+    static Signature requiredSignature() {
+        Signature signature;
+        signature.set(COMP_INDEX_CEnergy);
+        signature.set(COMP_INDEX_CHealth);
+        return signature;
+    }
+
     static constexpr float kStarvationDamagePerSecond{10.0f}; // Damage applied to entities that are starving
 
     void update(

include/EcoSimEngine/system/MovementSystem.hpp

@@ -8,6 +8,12 @@
 
 class MovementSystem : public System {
 public:
+    static Signature requiredSignature() {
+        Signature signature;
+        signature.set(COMP_INDEX_CTransform);
+        return signature;
+    }
+
     // EntityManager must implement getEntityById(size_t)
     void update(EntityManager& em, ComponentManager& cm, float dt)
     {

include/EcoSimEngine/system/SystemManager.hpp

@@ -27,18 +27,11 @@ class SystemManager {
         }
 
         auto system = std::make_shared<T>(std::forward<Args>(args)...);
-        m_systems.emplace(type, system);
-        return system;
-    }
 
-    template <typename T>
-    void SetSignature(const Signature& signature) {
-        const std::type_index type(typeid(T));
-        if (!m_systems.contains(type)) {
-            throw std::logic_error("Cannot set a signature for an unregistered system");
-        }
+        m_systems.emplace(type, system);
+        m_signatures.emplace(type, T::requiredSignature());
 
-        m_signatures[type] = signature;
+        return system;
     }
 
     void EntityDestroyed(EntityId id) {

src/simulation/SimulationWorld.cpp

@@ -1,39 +1,16 @@
 #include "EcoSimEngine/simulation/SimulationWorld.hpp"
 
-#include "EcoSimEngine/component/ComponentIndices.hpp"
-
 #include "EcoSimEngine/system/AISystem.hpp"
 #include "EcoSimEngine/system/MovementSystem.hpp"
 #include "EcoSimEngine/system/MetabolismSystem.hpp"
 
 SimulationWorld::SimulationWorld()
     : m_entityManager(m_systemManager, m_componentManager)
 {    
-    // Movement system
+    // Register systems
     m_systemManager.RegisterSystem<MovementSystem>();
-
-    Signature movementSignature;
-    movementSignature.set(COMP_INDEX_CTransform);
-
-    m_systemManager.SetSignature<MovementSystem>(movementSignature);
-
-    // AI system
     m_systemManager.RegisterSystem<AISystem>();
-
-    Signature aiSignature;
-    aiSignature.set(COMP_INDEX_CBehavior);
-    aiSignature.set(COMP_INDEX_CTransform);
-
-    m_systemManager.SetSignature<AISystem>(aiSignature);
-
-    // Metabolism system
     m_systemManager.RegisterSystem<MetabolismSystem>();
-
-    Signature metabolismSignature;
-    metabolismSignature.set(COMP_INDEX_CEnergy);
-    metabolismSignature.set(COMP_INDEX_CHealth);
-
-    m_systemManager.SetSignature<MetabolismSystem>(metabolismSignature);
 }
 
 void SimulationWorld::update(float dt)

tests/foundation_tests.cpp

@@ -31,9 +31,13 @@ namespace
 
     class TransformSystem final : public System
     {
-    };
-    class UnregisteredSystem final : public System
-    {
+    public:
+        static Signature requiredSignature()
+        {
+            Signature signature;
+            signature.set(COMP_INDEX_CTransform);
+            return signature;
+        }
     };
 
     void require(bool condition, const char *message)
@@ -140,21 +144,17 @@ namespace
         SystemManager systems;
         auto transformSystem = systems.RegisterSystem<TransformSystem>();
 
-        Signature required;
-        required.set(0);
-        systems.SetSignature<TransformSystem>(required);
-
         Signature entitySignature;
         systems.EntitySignatureChanged(11, entitySignature);
         require(!transformSystem->mEntities.contains(11),
                 "entity without required components must not join system");
 
-        entitySignature.set(0);
+        entitySignature.set(COMP_INDEX_CTransform);
         systems.EntitySignatureChanged(11, entitySignature);
         require(transformSystem->mEntities.contains(11),
                 "matching entity must join system");
 
-        entitySignature.reset(0);
+        entitySignature.reset(COMP_INDEX_CTransform);
         systems.EntitySignatureChanged(11, entitySignature);
         require(!transformSystem->mEntities.contains(11),
                 "entity must leave system after signature stops matching");
@@ -170,17 +170,6 @@ namespace
         }
         require(duplicateRejected, "duplicate system registration must fail in release builds too");
 
-        bool unregisteredSignatureRejected = false;
-        try
-        {
-            systems.SetSignature<UnregisteredSystem>(required);
-        }
-        catch (const std::logic_error &)
-        {
-            unregisteredSignatureRejected = true;
-        }
-        require(unregisteredSignatureRejected,
-                "setting a signature for an unregistered system must fail explicitly");
     }
 
     void testEntityDestruction()
@@ -191,10 +180,6 @@ namespace
 
         auto transformSystem = systems.RegisterSystem<TransformSystem>();
 
-        Signature required;
-        required.set(COMP_INDEX_CTransform);
-        systems.SetSignature<TransformSystem>(required);
-
         auto destroyedEntity = entities.addEntity("destroyed");
         auto survivingEntity = entities.addEntity("survivor");