Schedule systems based on their declared dependencies

[libs/game.git] / source / game / system.h

diff --git a/source/game/system.h b/source/game/system.h
index e3d71171c1e19aa8e31da854aa007737885774ce..09ee157a6953916522702cf0543ac75872f8ac78 100644 (file)
--- a/source/game/system.h
+++ b/source/game/system.h
@@ -20,11 +20,18 @@ public:
                READ_FRESH = 3,
                WRITE = 4,
                UPDATE = READ_OLD | WRITE,
-               CHAINED_UPDATE = READ_FRESH | WRITE
+               CHAINED_UPDATE = READ_FRESH | WRITE,
+               DATA_MASK = 7,
+               RUN_BEFORE = 8,
+               RUN_AFTER = 16,
+               ORDER_MASK = 24
        };
 
-       struct Dependency
+       class Dependency
        {
+               friend class System;
+
+       private:
                DependencyFlags flags = NO_DEPENDENCY;
                const Reflection::ClassBase &type;
                void (*prepare)(Stage &) = nullptr;
@@ -32,7 +39,11 @@ public:
                void (*unblock)(DependencyFlags) = nullptr;
                void (*block)(DependencyFlags) = nullptr;
 
+       public:
                Dependency(const Reflection::ClassBase &t): type(t) { }
+
+               DependencyFlags get_flags() const { return flags; }
+               const Reflection::ClassBase &get_type() const { return type; }
        };
 
        class Activator: public NonCopyable
@@ -63,6 +74,8 @@ protected:
        void declare_dependency(DependencyFlags);
 
 public:
+       const std::vector<Dependency> &get_dependencies() const { return dependencies; }
+
        void begin_tick();
        virtual void tick(Time::TimeDelta) = 0;
        void end_tick();
@@ -77,7 +90,9 @@ protected:
 template<typename T>
 inline void System::declare_dependency(DependencyFlags flags)
 {
-       if(!std::is_base_of_v<Component, T>)
+       if((flags&DATA_MASK) && !std::is_base_of_v<Component, T>)
+               throw std::invalid_argument("System::declare_dependency");
+       if((flags&ORDER_MASK) && !std::is_base_of_v<System, T>)
                throw std::invalid_argument("System::declare_dependency");
 
        const Reflection::ClassBase &type = stage.get_reflector().get_or_create_class<T>();
@@ -85,6 +100,8 @@ inline void System::declare_dependency(DependencyFlags flags)
 
        if(i!=dependencies.end())
                flags = static_cast<DependencyFlags>(flags|i->flags);
+       if((flags&RUN_BEFORE) && (flags&RUN_AFTER))
+               throw std::logic_error("conflicting order flags");
 
        Dependency &dep = (i!=dependencies.end() ? *i : dependencies.emplace_back(type));
        dep.flags = flags;