feat: add state machine

Assets/_Project/Develop/Runtime/Utilities/StatesManagement/ParallelState.cs

@@ -0,0 +1,32 @@
+using System.Collections.Generic;
+
+namespace Assets._Project.Develop.Runtime.Utilities.StateMachineCore
+{
+    public abstract class ParallelState<TState> : State where TState : class, IState
+    {
+        private List<TState> _states;
+
+        public ParallelState(params TState[] states)
+        {
+            _states = new List<TState>(states);
+        }
+
+        protected IReadOnlyList<TState> States => _states;
+
+        public override void Enter()
+        {
+            base.Enter();
+
+            foreach (TState state in _states)
+                state.Enter();
+        }
+
+        public override void Exit()
+        {
+            base.Exit();
+
+            foreach (TState state in _states)
+                state.Exit();
+        }
+    }
+}