Created LinkedList implementation of Ruby

LinkedList/Ruby/LinkedList.rb

@@ -0,0 +1,196 @@
+class LinkedList
+    def initialize
+        @head = nil
+    end
+
+    def addToFront(value)
+        if @head
+            new_head = Node.new(value)
+            new_head.next = @head
+            @head = new_head
+        else
+            @head = Node.new(value)
+        end
+    end
+
+
+    def addToBack(value)
+        if @head
+            find_tail.next = Node.new(value)
+        else
+            @head = Node.new(value)
+        end
+    end
+
+    # Inserts node at the specified index
+    def add_at(index, item)
+        if size > index
+            puts "Index is out of bounds"
+            return nil
+        elsif @head
+            if (index==0)
+                new_node = Node.new(value)
+                @head = new_node
+            elsif (index>0)
+                ind = index-1
+                before_insert = @head
+                ind.times do
+                    before_insert = before_insert.next
+                end
+                after_insert = before_insert.next
+
+                new_node = Node.new(value)
+                new_node.next = after_insert
+                before_insert = new_node
+            end        
+        else
+            new_node = Node.new(value)
+            @head = new_node
+        end
+    end
+
+    # Returns last node in LinkedList
+    def find_tail
+        node = @head
+        return node if !node.next
+        return node if !node.next while (node = node.next)
+    end
+
+    # Adds node after first occurrence of specified value
+    def append_after(target, value)
+        node           = find(target)
+        return unless node
+        old_next       = node.next
+        node.next      = Node.new(value)
+        node.next.next = old_next
+    end
+
+    # Helper functinon returning the first occurrence of a node with the target value
+    def find(value)
+        current_node = @head
+        return false if !current_node
+        return current_node  if current_node.value == value
+        while (current_node = current_node.next)
+            return current_node if current_node.value == value
+        end
+    end
+
+    # Removes first node from LinkedList without returning anything
+    def removeFromFront
+        if @head
+            old_head = @head
+            @head = old_head.next
+            old_head.next = nil
+        else
+            puts "The LinkedList is empty"
+        end 
+    end
+
+    # Removes last node from LinkedList without returning anything
+    def removeFromBack
+        if @head
+            if @head.next
+                current_node = @head
+                while current_node.next.next != nil
+                    current_node = current_node.next
+                end
+                current_node.next = nil
+            else
+                @head = nil
+            end
+        else
+            puts "The LinkedList is empty"
+        end
+    end 
+
+    def size
+        if @head
+            count = 1
+            current_node = @head
+            while current_node.next != nil
+                current_node = current_node.next
+                count += 1
+            end
+        else
+            count = 0
+        end
+        count
+    end
+
+    # Returns the node at a given index
+    def node_at(index)
+
+        if size >= index
+            puts "Index is out of bounds"
+            return nil
+        end
+
+        current=@head
+        index.times do
+            current=current.next_node
+        end
+        return current
+    end
+
+    # Removes node at specified index without returning anything
+    def remove(index)
+
+        if size >= index
+            puts "Index is out of bounds"
+            return nil
+        elsif @head
+            if (index==0)
+                old_head = @head
+                @head = @head.next
+                old_head.next = nil
+            elsif (index>0)
+                before_current = node_at(index-1)
+                current_node = before_current.next
+                before_current.next = current_node.next
+                current_node.next = nil
+            end
+        else
+            puts "The LinkedList is empty"
+        end
+    end
+
+    # delete first occurrence of value
+    def delete(value)
+        if @head.value == value
+            @head = @head.next
+            return
+        end
+        node      = find_before(value)
+        node.next = node.next.next
+    end
+
+    # Helper function that returns the node before a specific value
+    def find_before(value)
+        node = @head
+        return false if !node.next
+        return node  if node.next.value == value
+        while (node = node.next)
+            return node if node.next && node.next.value == value
+        end
+    end
+
+    def print
+        node = @head
+        puts node
+        while (node = node.next)
+            puts node
+        end
+    end
+
+    class Node
+        attr_accessor :next
+        attr_reader   :value
+        def initialize(value)
+            @value = value
+            @next  = nil
+        end
+        def to_s
+            "Node with value: #{@value}"
+        end
+    end
+end