From fd2b17ed0f01981ec82eaba58a401891c133b48c Mon Sep 17 00:00:00 2001
From: Jacob Signorovitch <jsignorovitch@commschool.org>
Date: Tue, 3 Dec 2024 15:47:18 -0500
Subject: [PATCH] The.

---
 deque/src/deque/Main.java | 35 +++++++++++++++++++++--------------
 1 file changed, 21 insertions(+), 14 deletions(-)

diff --git a/deque/src/deque/Main.java b/deque/src/deque/Main.java
index 0ee3146..1eaf481 100644
--- a/deque/src/deque/Main.java
+++ b/deque/src/deque/Main.java
@@ -17,26 +17,20 @@ class Examples {
 }
 
 // A doubly-linked list element.
-abstract class ANode<PointsTo> {
+abstract class ANode<T> {
 
-    PointsTo nxt; // Next element.
-    PointsTo pre; // Previous element.
+    ANode<T> nxt; // Next element.
+    ANode<T> pre; // Previous element.
 
-    ANode(PointsTo nxt, PointsTo pre) {
+    ANode(ANode<T> nxt, ANode<T> pre) {
         this.nxt = nxt;
         this.pre = pre;
     }
-}
 
-// Self-referential node.
-abstract class ASRefNode {
-
-    ASRefNode nxt;
-    ASRefNode pre;
-
-    ASRefNode() {
-        this.nxt = this;
-        this.pre = this;
+    void assignNode(ANode<T> nxt, ANode<T> pre) {
+        throw new UnsupportedOperationException(
+            "Can't call assignNode() on non-Node."
+        );
     }
 }
 
@@ -52,8 +46,10 @@ class Deque<A> {
 class Sentinel<T> extends ANode<ANode<T>> {
 
     Sentinel() {
+        // To create an empty list, this Sentinel points to itself.
         super(null, null);
         this.nxt = this;
+        this.pre = this;
     }
 }
 
@@ -65,4 +61,15 @@ class Node<T> extends ANode<Node<T>> {
         super(null, null);
         this.val = val;
     }
+
+    Node(T val, ANode<T> nxt, ANode<T> pre) {
+        this(val);
+        this.assignNode(nxt, pre);
+    }
+
+    void assignNode(ANode<T> nxt, ANode<T> pre) {
+        throw new UnsupportedOperationException(
+            "Can't call assignNode() on non-Node."
+        );
+    }
 }