first commit

lib/red_black_tree.rb

@@ -6,7 +6,11 @@
 class RedBlackTree
   include Utils
 
-  attr_reader :root
+  attr_reader :root, :size
+
+  def initialize
+    @size = 0
+  end
 
   # Traverses the tree, comparing existing nodes to the node to be added,
   # and inserts the node with the appropriate parent and direction.
@@ -25,6 +29,10 @@ def << node
   end
   alias_method :add, :<<
 
+  def empty?
+    @size == 0
+  end
+
   def insert! node, target_parent = nil, direction = nil
     if target_parent.nil?
       raise ArgumentError, "Target parent must be provided for tree with root" if @root
@@ -73,6 +81,8 @@ def insert! node, target_parent = nil, direction = nil
       @root.black!
     end
 
+    @size += 1
+
     self
   end
 
@@ -96,6 +106,6 @@ def rotate_sub_tree! node, direction
     opp_direction_child[direction] = node
     node.parent = opp_direction_child
 
-    opp_direction_child # new root
+    opp_direction_child # new sub-tree root
   end
 end

red-black-tree.gemspec

@@ -31,10 +31,4 @@ Gem::Specification.new do |spec|
   spec.bindir = "exe"
   spec.executables = spec.files.grep(%r{\Aexe/}) { |f| File.basename(f) }
   spec.require_paths = ["lib"]
-
-  # Uncomment to register a new dependency of your gem
-  # spec.add_dependency "example-gem", "~> 1.0"
-
-  # For more information and examples about making a new gem, check out our
-  # guide at: https://bundler.io/guides/creating_gem.html
 end