module Ancestry::MaterializedPath::InstanceMethods

def ancestor_ids 

def ancestor_ids
  parse_ancestry_column(read_attribute(self.ancestry_base_class.ancestry_column))
end

def ancestor_ids=(value) 

def ancestor_ids=(value)
  col = self.ancestry_base_class.ancestry_column
  value.present? ? write_attribute(col, value.join(ANCESTRY_DELIMITER)) : write_attribute(col, nil)
end

def ancestor_ids_before_last_save 

def ancestor_ids_before_last_save
  parse_ancestry_column(send("#{self.ancestry_base_class.ancestry_column}#{BEFORE_LAST_SAVE_SUFFIX}"))
end

def ancestor_ids_in_database 

def ancestor_ids_in_database
  parse_ancestry_column(send("#{self.ancestry_base_class.ancestry_column}#{IN_DATABASE_SUFFIX}"))
end

def ancestors?

optimization - better to go directly to column and avoid parsing 
def ancestors?
  read_attribute(self.ancestry_base_class.ancestry_column).present?
end

def child_ancestry

This is technically child_ancestry_was
The ancestry value for this record's children (before save)
private (public so class methods can find it) 
def child_ancestry
  # New records cannot have children
  raise Ancestry::AncestryException.new(I18n.t("ancestry.no_child_for_new_record")) if new_record?
  path_was = self.send("#{self.ancestry_base_class.ancestry_column}#{IN_DATABASE_SUFFIX}")
  path_was.blank? ? id.to_s : "#{path_was}/#{id}"
end

def parent_id_before_last_save 

def parent_id_before_last_save
  ancestry_was = send("#{self.ancestry_base_class.ancestry_column}#{BEFORE_LAST_SAVE_SUFFIX}")
  return unless ancestry_was.present?
  parse_ancestry_column(ancestry_was).last
end

def parse_ancestry_column obj 

def parse_ancestry_column obj
  return [] unless obj
  obj_ids = obj.split(ANCESTRY_DELIMITER)
  self.class.primary_key_is_an_integer? ? obj_ids.map!(&:to_i) : obj_ids
end

def sibling_of?(node)

optimization - better to go directly to column and avoid parsing 
def sibling_of?(node)
  self.read_attribute(self.ancestry_base_class.ancestry_column) == node.read_attribute(self.ancestry_base_class.ancestry_column)
end