Basic ECS setup.

- Added std::variant to pch.h

include/ecs/ecs.h

@@ -1,14 +1,27 @@
 #ifndef ECS_H
 #define ECS_H
 
+#include "bindings/ruby.h"
 #include "utils.h"
 
-struct Entity {};
-struct Component;
-struct System;
+struct Entity {
+  Vec2<float> position;
+  std::unordered_map<std::string, size_t> components;
+};
 
-struct EntityPool {
-  Entity entities[];
+struct Component {
+  enum struct Type {
+    Int,
+    Float,
+    Boolean,
+    RubyObject
+  };
+  std::unordered_map<std::string, std::variant<int64_t, double, bool, Ruby::RubyObject>> globals;
+  std::vector<std::tuple<std::string, Type, void *>> table;
+};
+
+struct System {
+  Ruby::Block function;
 };
 
 #endif

include/pch.h

@@ -69,6 +69,7 @@
 #include <unistd.h>
 #include <unordered_map>
 #include <unordered_set>
+#include <variant>
 #include <vector>
 
 #endif