ruby - linked-list

ruby/linked-list/linked_list.rb

@@ -0,0 +1,48 @@
+# Deque class
+class Deque
+  def initialize
+    @front = nil
+    @back = nil
+  end
+
+  def push(data)
+    element = Element.new(data)
+    element.prev = @back
+    @back.next = element if @back
+    @back = element
+    @front = element if @front.nil?
+  end
+
+  def pop
+    element = @back
+    @back = element.prev
+    @front = nil if @back.nil?
+    element.data
+  end
+
+  def unshift(data)
+    element = Element.new(data)
+    element.next = @front
+    @front.prev = element if @front
+    @front = element
+    @back = element if @back.nil?
+  end
+
+  def shift
+    element = @front
+    @front = element.next
+    @back = nil if @front.nil?
+    element.data
+  end
+end
+
+# Element class
+class Element
+  attr_accessor :data, :next, :prev
+
+  def initialize(data)
+    @data = data
+    @next = nil
+    @prev = nil
+  end
+end