Hash/Array Tree searcher

node.rb

# > n = Node.find_where(terms2){|v| !v["Section"].empty?}
# => #<Node key="Sections" value=Hash children=1> 
# > puts n.path
# => [0]["Departments"]["Department"][3]["Courses"]["Course"][1]["Sections"]
class Node
  attr_reader :parent, :key, :value, :children
  def initialize(parent, key, value)
    @parent = parent
    @key = key
    @value = value
    @children = case value
    when Hash
      value.map{|k, v| self.class.new(self, k, v)}
    when Enumerable
      value.map.with_index{|e, i| self.class.new(self, i, e)}
    else
      []
    end
  end

  def self.find_where(obj, &block)
    new(nil, nil, obj).find_where(&block)
  end

  def find_where(&block)
    if block.call(value)
      self
    else
      for child in children
        return node if node = child.find_where(&block)
      end
      nil
    end
  rescue
    for child in children
      return node if node = child.find_where(&block)
    end
    nil
  end

  def inspect
    "#<Node key=#{key.inspect} value=#{value.class} children=#{children.size} parent=#{parent ? parent.key : 'nil'}>"
  end

  def path
    if parent
      parent.path + "[#{key.inspect}]"
    else
      ""
    end
  end
end