General purpose binary tree implemented in Ruby.

btree.rb

class BTree
	attr_accessor :root, :size

	class Node
		attr_accessor :parent, :data, :left, :right

		def initialize parent, data
			self.parent = parent
			self.data   = data
		end

		def to_s
			puts self.data
			puts self.left
			puts self.right
		end
	end

	def initialize root
		self.root = root
		self.size = 1
	end

	# Inserts a new node at the left child of the specified node. 
	def insert_left(node, data)
		return unless node
		raise "Can't override nodes :(" if node.left

		self.size += 1
		node.left = Node.new node, data
	end

	# Inserts a new node at the right child of the specified node. 
	def insert_right(node, data)
		return unless node
		raise "Can't override nodes :(" if node.right

		self.size += 1
		node.right = Node.new node, data
	end

	# Removes the subtree rooted at the left child of the specified node.
	def remove_left(node)
		if node&.left
			remove_left(node.left)
			remove_right(node.left)
			node.left = nil
			self.size -= 1
		end
	end

	# Removes the subtree rooted at the right child of the specified node.
	def remove_right(node)
		if node&.right
			remove_left node.right
			remove_right node.right
			node.right = nil
			self.size -= 1
		end
	end

	# Produces a new tree by merging the left and right trees.
	def self.merge left_tree, right_tree, data = nil
		raise "Can't merge nil trees." unless left_tree && right_tree

		root           = Node.new(nil, data);
		res            = BTree.new root
		res.root.left  = left_tree.root
		res.root.right = right_tree.root
		res.size       = left_tree.size + right_tree.size
		res
	end

	# Print the contents of the tree.
	def print
		print_rec self.root
	end

	def to_s
		puts self.root
	end

private
	# Prints nodes recursively
	def print_rec node, indent=0
		print_node node, indent
		print_rec node.left, indent  + 1 if node&.left
		print_rec node.right, indent + 1 if node&.right
	end

	# Prints node's data.
	def print_node node, indent
		data = node&.data&.to_s || "nil"
		puts data.rjust indent * 4, " "
	end
end