add binary tree

Author: phluid61

trees/binary_tree.rb

@@ -0,0 +1,85 @@
+
+class BinaryTree
+  class Node
+    def initialize value, parent, comparator
+      @value  = value
+      @parent = parent
+      @left  = nil
+      @right = nil
+      @cmp = comparator
+    end
+    attr_accessor :value
+
+    ##
+    # Add a value to the tree, below this node.
+    # Returns the new node.
+    def add value
+      if @cmp.call(@value, value) < 0
+        if @left
+          @left.add value, cmp
+        else
+          @left = Node.new value, self, @cmp
+        end
+      else
+        if @right
+          @right.add value
+        else
+          @right = Node.new value, self, @cmp
+        end
+      end
+    end
+
+    ##
+    # Recursively yield left/this/right value.
+    def each &block
+      return enum_for(:each) unless block_given?
+      @left.each(&block) if @left
+      yield @value
+      @right.each(&block) if @right
+      nil
+    end
+  end
+
+  include Enumerable
+
+  ##
+  # Create a new self-sorting binary tree.
+  #
+  # If called with a block, it is used as the comparison function
+  # for sorting values.  By default values are compared using the
+  # spaceship operator <=>
+  #
+  #  @yield |a, b|  =>  {-1, 0, 1}
+  #
+  def initialize &comparator
+    comparator = lambda {|a, b| a <=> b } if !comparator
+    @cmp = comparator
+    @root = nil
+    @length = 0
+  end
+  attr_reader :length
+
+  ##
+  # Add a new value to the tree.
+  def add value
+    if !@root
+      @root = Node.new value, nil, @cmp
+      @length = 1
+    else
+      @root.add value
+      @length += 1
+    end
+    value
+  end
+
+  ##
+  # Iterator over each element in the tree, in order.
+  #
+  #  @yield |value|
+  def each &block
+    return enum_for(:each) unless block_given?
+    return if !@root
+    @root.each &block
+  end
+end
+