init: add project

Assets/_Project/Develop/Runtime/Utilities/ReactiveManagement/Variable/ReactiveVariable.cs

@@ -0,0 +1,61 @@
+using System;
+using System.Collections.Generic;
+
+namespace _Project.Develop.Runtime.Utils.ReactiveManagement
+{
+    public class ReactiveVariable<T> : IReadOnlyVariable<T> where T : IEquatable<T>
+    {
+        private readonly List<Subscriber<T, T>> _subscribers = new ();
+        private readonly List<Subscriber<T, T>> _toAddList = new ();
+        private readonly List<Subscriber<T, T>> _toRemoveList = new ();
+        
+        public ReactiveVariable() => _value = default(T);
+    
+        public ReactiveVariable(T value) => _value = value;
+        
+        private T _value;
+    
+        public T Value
+        {
+            get => _value;
+            set
+            {
+                T oldValue = _value;
+                _value = value;
+
+                if (_value.Equals(oldValue) == false)
+                    Invoke(oldValue, _value);
+            }
+        }
+        
+        public IDisposable Subscribe(Action<T, T> action) 
+            {
+                Subscriber<T, T> subscriber = new (action, RemoveSubscriber);
+                _toAddList.Add(subscriber);
+
+                return subscriber;
+            }
+        
+        private void RemoveSubscriber(Subscriber<T, T> subscriber) => _toRemoveList.Add(subscriber);
+
+        private void Invoke(T oldValue, T newValue)
+        {
+            if(_toAddList.Count > 0)
+            {
+                _subscribers.AddRange(_toAddList);
+                _toAddList.Clear();
+            }
+            
+            if(_toRemoveList.Count > 0)
+            {
+                foreach (Subscriber<T, T> subscriber in _toRemoveList)
+                    _subscribers.Remove(subscriber);
+                
+                _toRemoveList.Clear();
+            }
+            
+            foreach (Subscriber<T, T> subscriber in _subscribers)
+                subscriber.Invoke(oldValue, newValue);
+        }
+    }
+}