preparation for circularly linked lists

Signed-off-by: Mattias Andrée <maandree@operamail.com>

5 files changed, 40 insertions, 15 deletions

diff --git a/src/datastructures/linkedlists/DoublyLinkedList.java b/src/datastructures/linkedlists/DoublyLinkedList.java
index 7bb091d..c84172c 100644
--- a/src/datastructures/linkedlists/DoublyLinkedList.java
+++ b/src/datastructures/linkedlists/DoublyLinkedList.java
@@ -35,6 +35,6 @@ package datastructures.linkedlists;
  * @param  <T>  The value stored in the structure
  */
 public class DoublyLinkedList<T>
-£>export with_tail=1 with_prev=1
+£>export with_head=1 with_tail=1 with_prev=1
 £>gpp -s £ < src/datastructures/linkedlists/template | sed -e '/^[/ ]\*/d'
 
diff --git a/src/datastructures/linkedlists/SinglyLinkedList.java b/src/datastructures/linkedlists/SinglyLinkedList.java
index 6633941..9e39809 100644
--- a/src/datastructures/linkedlists/SinglyLinkedList.java
+++ b/src/datastructures/linkedlists/SinglyLinkedList.java
@@ -35,6 +35,6 @@ package datastructures.linkedlists;
  * @param  <T>  The value stored in the structure
  */
 public class SinglyLinkedList<T>
-£>export with_tail=1 with_prev=0
+£>export with_head=1 with_tail=1 with_prev=0
 £>gpp -s £ < src/datastructures/linkedlists/template | sed -e '/^[/ ]\*/d'
 
diff --git a/src/datastructures/linkedlists/TaillessDoublyLinkedList.java b/src/datastructures/linkedlists/TaillessDoublyLinkedList.java
index 0304ea9..fa3c3e6 100644
--- a/src/datastructures/linkedlists/TaillessDoublyLinkedList.java
+++ b/src/datastructures/linkedlists/TaillessDoublyLinkedList.java
@@ -18,8 +18,8 @@ package datastructures.linkedlists;
 
 
 /**
- * Doubly linked list class. A linked list is a
- * list constructed from nodes, which hold stored
+ * Tailless doubly linked list class. A linked list
+ * is a list constructed from nodes, which hold stored
  * values, with references to each other, this is
  * usally an ineffective data structure, especially
  * on high-level object orientated languages. A
@@ -35,6 +35,6 @@ package datastructures.linkedlists;
  * @param  <T>  The value stored in the structure
  */
 public class TaillessDoublyLinkedList<T>
-£>export with_tail=0 with_prev=1
+£>export with_head=1 with_tail=0 with_prev=1
 £>gpp -s £ < src/datastructures/linkedlists/template | sed -e '/^[/ ]\*/d'
 
diff --git a/src/datastructures/linkedlists/TaillessSinglyLinkedList.java b/src/datastructures/linkedlists/TaillessSinglyLinkedList.java
index aecd612..2c66eb3 100644
--- a/src/datastructures/linkedlists/TaillessSinglyLinkedList.java
+++ b/src/datastructures/linkedlists/TaillessSinglyLinkedList.java
@@ -18,7 +18,7 @@ package datastructures.linkedlists;
 
 
 /**
- * Taileess singly linked list class. A linked list
+ * Tailless singly linked list class. A linked list
  * is a list constructed from nodes, which hold
  * stored values, with references to each other,
  * this is usally an ineffective data structure,
@@ -34,6 +34,6 @@ package datastructures.linkedlists;
  * @param  <T>  The value stored in the structure
  */
 public class TaillessSinglyLinkedList<T>
-£>export with_tail=0 with_prev=0
+£>export with_head=1 with_tail=0 with_prev=0
 £>gpp -s £ < src/datastructures/linkedlists/template | sed -e '/^[/ ]\*/d'
 
diff --git a/src/datastructures/linkedlists/template b/src/datastructures/linkedlists/template
index b0311b5..0a24a89 100644
--- a/src/datastructures/linkedlists/template
+++ b/src/datastructures/linkedlists/template
@@ -54,10 +54,12 @@
     
     
     
+£>if (( with_head )); then
     /**
      * The first node in the list
      */
     public Node head = null;
+£>fi
     
 £>if (( with_tail )); then
     /**
@@ -67,12 +69,29 @@
 £>fi
     
     
+
+£>if (( 1 - with_head )) && (( 1 - with_tail )); then
+    /**
+     * Creates the initial node in a circularly linked list
+     * 
+     * @param   value  The value of the initial node
+     * @return         The node that has been created and inserted
+     */
+    public Node create(T value)
+    {
+	Node node = new Node(value);
+£>(( with_prev )) &&
+	node.previous = node;
+	return node.next = node;
+    }
+£>fi
     
+£>if (( with_head )); then
     /**
      * Insert a value in the beginning of the list
      * 
      * @param   value  The value to insert
-     * @return         The node that has be created and inserted
+     * @return         The node that has been created and inserted
      */
     public Node insertBeginning(T value)
     {
@@ -110,13 +129,14 @@
 £>fi
 	return node;
     }
+£>fi
     
     /**
      * Insert a value after a specified, reference, node
      * 
      * @param   value        The value to insert
      * @param   predecessor  The reference node
-     * @return               The node that has be created and inserted
+     * @return               The node that has been created and inserted
      */
     public Node insertAfter(T value, Node predecessor)
     {
@@ -163,7 +183,7 @@
      * 
      * @param   value      The value to insert
      * @param   successor  The reference node
-     * @return             The node that has be created and inserted
+     * @return             The node that has been created and inserted
      */
     public Node insertBefore(T value, Node successor)
     {
@@ -173,8 +193,10 @@
 	node.next = successor;
 	if (node.previous != null)
 	    node.previous.next = node;
+£>if (( with_tail )); then
 	if (this.head == successor)
 	    this.head = node;
+£>fi
 	return node;
     }
     
@@ -191,8 +213,10 @@
 	    successor.previous = node.previous;
 	else if (node.previous != null)
 	    node.previous.next = successor;
+£>if (( with_head )); then
 	if (this.head == node)
 	    this.head = successor;
+£>fi
 	return node;
     }
     
@@ -203,11 +227,12 @@
      */
     public void remove(Node node)
     {
-	if (node.previous == null)
-	    this.head = node.next;
-	else
+	if (node.previous != null)
 	    node.previous.next = node.next;
-	
+£>if (( with_head )); then
+	else
+	    this.head = node.next;
+£>fi	
 	if (node.next != null)
 	    node.next.previous = node.previous;
 £>if (( with_tail )); then
@@ -222,7 +247,7 @@
      * Insert a value in the end of the list
      * 
      * @param   value  The value to insert
-     * @return         The node that has be created and inserted
+     * @return         The node that has been created and inserted
      */
     public Node insertEnd(T value)
     {