Schedule systems based on their declared dependencies

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

diff --git a/source/game/systemscheduler.h b/source/game/systemscheduler.h
new file mode 100644 (file)
index 0000000..2ab4804
--- /dev/null
+++ b/source/game/systemscheduler.h
@@ -0,0 +1,54 @@
+#ifndef MSP_GAME_SYSTEMSCHEDULER_H_
+#define MSP_GAME_SYSTEMSCHEDULER_H_
+
+#include <vector>
+#include "reflection.h"
+
+namespace Msp::Game {
+
+class System;
+
+class scheduling_error: public std::logic_error
+{
+public:
+       scheduling_error(const std::string &w): logic_error(w) { }
+};
+
+class SystemScheduler
+{
+public:
+       struct Group
+       {
+               std::vector<System *> systems;
+       };
+
+private:
+       struct GraphNode
+       {
+               System *system = nullptr;
+               Reflection::ClassBase *type = nullptr;
+               std::vector<GraphNode *> predecessors;
+               unsigned scheduled_order = 0;
+       };
+
+       Reflection::Reflector &reflector;
+       std::vector<GraphNode> nodes;
+       std::vector<Group> groups;
+
+public:
+       SystemScheduler(Reflection::Reflector &);
+
+       void add_system(System &);
+       void remove_system(System &);
+       void schedule();
+private:
+       static int get_order(const GraphNode &, const GraphNode &);
+       static int get_explicit_order(const GraphNode &, const GraphNode &);
+       static int get_data_order(const GraphNode &, const GraphNode &);
+public:
+       const std::vector<Group> &get_groups() const { return groups; }
+};
+
+} // namespace Msp::Game
+
+#endif