Initial checkin - helper for memoizing Supplier-style functions

qqq-backend-core/src/main/java/com/kingsrook/qqq/backend/core/utils/memoization/AnyKey.java

@@ -0,0 +1,78 @@
+/*
+ * QQQ - Low-code Application Framework for Engineers.
+ * Copyright (C) 2021-2024.  Kingsrook, LLC
+ * 651 N Broad St Ste 205 # 6917 | Middletown DE 19709 | United States
+ * contact@kingsrook.com
+ * https://github.com/Kingsrook/
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.kingsrook.qqq.backend.core.utils.memoization;
+
+
+/*******************************************************************************
+ ** Meant to serve as the key in a Memoization where we actually don't need a parameter.
+ ** e.g., to memoize a function like:  public Object f();
+ *******************************************************************************/
+public class AnyKey
+{
+   private static AnyKey anyKey = null;
+
+
+
+   /*******************************************************************************
+    ** Singleton constructor
+    *******************************************************************************/
+   private AnyKey()
+   {
+
+   }
+
+
+
+   /*******************************************************************************
+    ** Singleton accessor
+    *******************************************************************************/
+   public static AnyKey getInstance()
+   {
+      if(anyKey == null)
+      {
+         anyKey = new AnyKey();
+      }
+      return (anyKey);
+   }
+
+
+
+   /*******************************************************************************
+    **
+    *******************************************************************************/
+   @Override
+   public boolean equals(Object obj)
+   {
+      return (obj == this);
+   }
+
+
+
+   /*******************************************************************************
+    **
+    *******************************************************************************/
+   @Override
+   public int hashCode()
+   {
+      return 1;
+   }
+}