module CollectiveIdea::Acts::NestedSet

def acts_as_nested_set(options = {})

to acts_as_nested_set models
CollectiveIdea::Acts::NestedSet::Model for a list of instance methods added
See CollectiveIdea::Acts::NestedSet::Model::ClassMethods for a list of class methods and

Example: acts_as_nested_set :order_column => :position
* +:order_column+ on which column to do sorting, by default it is the left_column_name
Example: acts_as_nested_set :counter_cache => :children_count
defaults to false.
* +:counter_cache+ adds a counter cache for the number of children.
without calling their destroy method.
method. If set to :delete_all (default), all the child objects are deleted
child objects are destroyed alongside this object by calling their destroy
* +:dependent+ - behavior for cascading destroy. If set to :destroy, all the
Example: acts_as_nested_set :scope => [:notable_id, :notable_type]
can also pass an array to scope by multiple attributes.
(if it hasn't been already) and use that as the foreign key restriction. You
* +:scope+ - restricts what is to be considered a list. Given a symbol, it'll attach "_id"
* +:depth_column+ - column name for the depth data, default "depth"
* +:right_column+ - column name for right boundary data, default "rgt"
* +:left_column+ - column name for left boundary data, default "lft"
* +:primary_column+ - specifies the column name to use as the inverse of the parent column (default: id)
* +:parent_column+ - specifies the column name to use for keeping the position integer (default: parent_id)

Configuration options are:

def acts_as_nested_set(options = {})
  acts_as_nested_set_parse_options! options
  include Model
  include Columns
  extend Columns
  acts_as_nested_set_relate_parent!
  acts_as_nested_set_relate_children!
  attr_accessor :skip_before_destroy
  acts_as_nested_set_prevent_assignment_to_reserved_columns!
  acts_as_nested_set_define_callbacks!
end

def acts_as_nested_set_default_options

def acts_as_nested_set_default_options
  {
    :parent_column => 'parent_id',
    :primary_column => 'id',
    :left_column => 'lft',
    :right_column => 'rgt',
    :depth_column => 'depth',
    :dependent => :delete_all, # or :destroy
    :polymorphic => false,
    :counter_cache => false,
    :touch => false
  }.freeze
end

def acts_as_nested_set_define_callbacks!

def acts_as_nested_set_define_callbacks!
  # on creation, set automatically lft and rgt to the end of the tree
  before_create  :set_default_left_and_right
  before_save    :store_new_parent
  after_save     :move_to_new_parent, :set_depth!
  before_destroy :destroy_descendants
  define_model_callbacks :move
end

def acts_as_nested_set_parse_options!(options)

def acts_as_nested_set_parse_options!(options)
  options = acts_as_nested_set_default_options.merge(options)
  if options[:scope].is_a?(Symbol) && options[:scope].to_s !~ /_id$/
    options[:scope] = "#{options[:scope]}_id".intern
  end
  class_attribute :acts_as_nested_set_options
  self.acts_as_nested_set_options = options
end

def acts_as_nested_set_prevent_assignment_to_reserved_columns!

def acts_as_nested_set_prevent_assignment_to_reserved_columns!
  # no assignment to structure fields
  [left_column_name, right_column_name, depth_column_name].each do |column|
    module_eval <<-"end_eval", __FILE__, __LINE__
      def #{column}=(x)
        raise ActiveRecord::ActiveRecordError, "Unauthorized assignment to #{column}: it's an internal field handled by acts_as_nested_set code, use move_to_* methods instead."
      end
    end_eval
  end
end

def acts_as_nested_set_relate_children!

def acts_as_nested_set_relate_children!
  has_many_children_options = {
    :class_name => self.base_class.to_s,
    :foreign_key => parent_column_name,
    :primary_key => primary_column_name,
    :inverse_of => (:parent unless acts_as_nested_set_options[:polymorphic]),
  }
  # Add callbacks, if they were supplied.. otherwise, we don't want them.
  [:before_add, :after_add, :before_remove, :after_remove].each do |ar_callback|
    has_many_children_options.update(
      ar_callback => acts_as_nested_set_options[ar_callback]
    ) if acts_as_nested_set_options[ar_callback]
  end
  has_many :children, -> { order(order_column_name) },
           **has_many_children_options
end

def acts_as_nested_set_relate_parent!

def acts_as_nested_set_relate_parent!
  options = {
    :class_name => self.base_class.to_s,
    :foreign_key => parent_column_name,
    :primary_key => primary_column_name,
    :counter_cache => acts_as_nested_set_options[:counter_cache],
    :inverse_of => (:children unless acts_as_nested_set_options[:polymorphic]),
    :touch => acts_as_nested_set_options[:touch]
  }
  options[:polymorphic] = true if acts_as_nested_set_options[:polymorphic]
  options[:optional] = true if ActiveRecord::VERSION::MAJOR >= 5
  belongs_to :parent, **options
end

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