gistfile1.rb

class Element
  def initialize(tag_name)
    @tag_name = tag_name
    @classes = []
  end

  def tag_name
    @tag_name
  end

  def add_class(css_class)
    @classes << css_class
    self
  end

  def remove_class(css_class)
    @classes.remove(css_class)
    self
  end

  def has_class?(css_class)
    @classes.include?(css_class)
  end

  def classes
    @classes
  end
end

# Selector base class
class Selector
  def matches?(element)
    false
  end
end

# # # # # # # # # # # # # # # # # # # #
# Example selectors
# # # # # # # # # # # # # # # # # # # #
class TagSelector
  def initialize(tag_name)
    @tag_name = tag_name
  end

  def matches?(element)
    element.tag_name == @tag_name
  end
end

class ClassSelector
  def initialize(css_class)
    @css_class = css_class
  end

  def matches?(element)
    element.has_class?(@css_class)
  end
end

class CombinedSelector
  def initialize
    @selectors = []
  end

  def add_selector(selector)
    @selectors.add(selector)
  end

  def matches?
    @selectors.all?{ |selector| selector.matches?(element) }
  end
end