requirements for exit door

Assets/Escape Room Engine/Engine/Scripts/Requirements/Requirement.cs

@@ -1,9 +1,27 @@
-using UnityEngine;
+using System.Collections.Generic;
+using Escape_Room_Engine.Engine.Scripts.Modules;
+using UnityEngine;
 
 namespace Escape_Room_Engine.Engine.Scripts.Requirements
 {
-    public abstract class Requirement : ScriptableObject
+    public abstract class Requirement<T> : ScriptableObject
     {
-        
+        protected abstract IEnumerable<T> GenerateCandidates(Module module, Space space);
+
+        public void Restrict(HashSet<T> candidates, Module module, Space space) =>
+            candidates.IntersectWith(GenerateCandidates(module, space));
+
+        public static HashSet<T> Candidates(
+            HashSet<T> initialCandidates,
+            IEnumerable<Requirement<T>> requirements,
+            Module module, Space space)
+        {
+            foreach (var requirement in requirements)
+            {
+                requirement.Restrict(initialCandidates, module, space);
+            }
+
+            return initialCandidates;
+        }
     }
 }