Module: Forestify::InstanceMethods

Defined in:
lib/forestify.rb

Instance Method Summary collapse

Instance Method Details

#children ⇒ Object 



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# File 'lib/forestify.rb', line 58

def children
    [] if is_leaf?
	self.class.where('left_position > ?', self.left_position).where('right_position < ?', self.right_position)
end

#initialize_position ⇒ Object

Initialize position fields Should be run only once



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# File 'lib/forestify.rb', line 15

def initialize_position
	# @parent = -1 is the option 'No parent'
	if @parent.nil? || @parent == "-1"
		# No parent has been specified, we need to add this leaf
		# to the right side of the last root node.
		last = self.class.order("right_position DESC").first
		self.left_position = (last.nil?) ? 0 : last.right_position + 1
		self.right_position = self.left_position + 1
		self.level = 0
	else
		# Makes sure it's an integer
		@parent = @parent.to_i
		p = self.class.find(@parent)
		self.left_position = p.right_position
		self.right_position = self.left_position + 1
		self.level = p.level + 1
		# update nodes on the right hand side of parent
		self.class.update_all "left_position = left_position + 2", ['left_position > ?', p.right_position]
		self.class.update_all "right_position = right_position + 2", ['right_position > ?', p.right_position]
		# update parent
		p.update_attribute 'right_position', p.right_position + 2
	end
end

#is_leaf? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/forestify.rb', line 67

def is_leaf?
	!is_node?
end

#is_node? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/forestify.rb', line 63

def is_node?
	(self.right_position - self.left_position) > 1
end

#parents ⇒ Object 



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# File 'lib/forestify.rb', line 54

def parents
	self.class.where('left_position < ?', self.left_position).where('right_position > ?', self.right_position)
end

#update_positions_after_delete ⇒ Object 



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# File 'lib/forestify.rb', line 39

def update_positions_after_delete
	if is_node?
		# Update nodes to the right
		self.class.update_all "left_position = left_position - 2", ['left_position > ?', self.right_position]
		self.class.update_all "right_position = right_position - 2", ['right_position > ?', self.right_position]
		# Update children
		self.class.update_all "level = level - 1", ['left_position > ? AND right_position < ?', self.left_position, self.right_position]
		self.class.update_all "left_position = left_position - 1, right_position = right_position - 1", ['left_position > ? AND right_position < ?', self.left_position, self.right_position]
	else
		self.class.update_all "left_position = left_position - 2", ['left_position > ?', self.right_position]
		self.class.update_all "right_position = right_position - 2", ['right_position > ?', self.right_position]
	end
end