# File lib/sass/tree/visitors/cssize.rb, line 43
  def with_parent(parent)
    if parent.is_a?(Sass::Tree::DirectiveNode)
      if MERGEABLE_DIRECTIVES.any? {|klass| parent.is_a?(klass)}
        old_parent_directive = @parent_directives.pop
      end
      @parent_directives.push parent
    end

    old_parent, @parent = @parent, parent
    yield
  ensure
    @parent_directives.pop if parent.is_a?(Sass::Tree::DirectiveNode)
    @parent_directives.push old_parent_directive if old_parent_directive
    @parent = old_parent
  end