module Haml::AttributeBuilder

def build_class(escape_attrs, *values)
  if values.size == 1
    value = values.first
    case
    when value.is_a?(String)
      # noop
    when value.is_a?(Array)
      value = value.flatten.select { |v| v }.map(&:to_s).uniq.join(' ')
    when value
      value = value.to_s
    else
      return ''
    end
    return escape_html(escape_attrs, value)
  end
  classes = []
  values.each do |value|
    case
    when value.is_a?(String)
      classes += value.split(' ')
    when value.is_a?(Array)
      classes += value.select { |v| v }
    when value
      classes << value.to_s
    end
  end
  escape_html(escape_attrs, classes.map(&:to_s).uniq.join(' '))
end