Module: FastTree::Model

Extended by:
ActiveSupport::Concern
Defined in:
lib/fast_tree.rb,
lib/fast_tree/model.rb,
lib/fast_tree/model/subtree/traverse.rb

Defined Under Namespace

Modules: ClassMethods, Subtree Classes: InvalidTreeStructureError

Instance Method Summary collapse

Instance Method Details

#add_child(node) ⇒ Object

Instance Methods



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# File 'lib/fast_tree/model.rb', line 148

def add_child(node)
  # bulk update nodes by a sql query
  _update_nodes(r_ptr, r_ptr, "r_ptr >= #{r_ptr}")

  # child node's pointer
  node.l_ptr = r_ptr
  node.r_ptr = r_ptr + 1
  node.depth = depth + 1
  node.save
end

#children ⇒ Object 



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# File 'lib/fast_tree/model.rb', line 275

def children
  self.class.where(self.class.arel_table[:l_ptr].gt(l_ptr))
            .where(self.class.arel_table[:r_ptr].lt(r_ptr))
            .where(depth: depth + 1)
end

#copy_to(node) ⇒ Object 



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# File 'lib/fast_tree/model.rb', line 170

def copy_to(node)
  # create empty space into which subtree embedded
  _update_nodes(node.l_ptr, node.r_ptr, "r_ptr >= #{node.r_ptr}", width + 1)

  # self and node may be updated by shifting
  self.reload
  node.reload

  bias = node.r_ptr - r_ptr - 1
  base_depth = depth
  self.subtree.each do |st_node|
    attributes = st_node.attributes.to_h
    attributes.delete("id")
    attributes["l_ptr"] += bias
    attributes["r_ptr"] += bias
    attributes["depth"] += node.depth - base_depth + 1
    self.class.create(attributes)
  end
end

#create_child(attributes = {}, &block) ⇒ Object 



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# File 'lib/fast_tree/model.rb', line 159

def create_child(attributes = {}, &block)
  # bulk update nodes by a sql query
  _update_nodes(r_ptr, r_ptr, "r_ptr >= #{r_ptr}")

  # create child
  attributes[:l_ptr] = r_ptr
  attributes[:r_ptr] = r_ptr + 1
  attributes[:depth] = depth + 1
  self.class.create(attributes, &block)
end

#has_children? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/fast_tree/model.rb', line 260

def has_children?
  l_ptr != r_ptr - 1
end

#leaf? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/fast_tree/model.rb', line 256

def leaf?
  l_ptr == r_ptr - 1
end

#move_to(node) ⇒ Object 



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# File 'lib/fast_tree/model.rb', line 190

def move_to(node)
  # NOTE:
  # copy_to and remove change node ids
  # move operation should change nothing but left and right pointers

  # create empty spaces under the node
  _update_nodes(node.r_ptr, node.r_ptr, "r_ptr >= #{node.r_ptr}", width + 1)

  self.reload
  node.reload

  # remember where the node were
  empty_space_left = self.l_ptr
  empty_space_right = self.r_ptr

  # move subtree under the given node
  bias = node.r_ptr - r_ptr - 1
  base_depth = depth
  self.subtree.each do |st_node|
    st_node.l_ptr += bias
    st_node.r_ptr += bias
    st_node.depth += node.depth - base_depth + 1
    st_node.save
  end

  self.reload
  node.reload

  # fill (virtual) empty spaces that will be created by moving subtree
  _update_nodes(empty_space_left, empty_space_right, "r_ptr > #{empty_space_right}", - (width + 1))
end

#parent ⇒ Object

Getter Methods



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# File 'lib/fast_tree/model.rb', line 268

def parent
  self.class.where(self.class.arel_table[:l_ptr].lt(l_ptr))
            .where(self.class.arel_table[:r_ptr].gt(r_ptr))
            .where(depth: depth - 1)
            .try(:first)
end

#path ⇒ Object 



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# File 'lib/fast_tree/model.rb', line 233

def path
  self.class.where(self.class.arel_table[:l_ptr].lteq(l_ptr))
            .where(self.class.arel_table[:r_ptr].gteq(r_ptr))
            .order(l_ptr: :asc)
end

#print_subtree ⇒ Object 



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# File 'lib/fast_tree/model.rb', line 239

def print_subtree
  self.class.print_subtree(self)
end

#remove ⇒ Object 



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# File 'lib/fast_tree/model.rb', line 222

def remove
  # remove subtree
  n_destroyed = self.class.find_subtree_by_root(self).destroy_all

  # fill empty space
  _update_nodes(l_ptr, r_ptr, "r_ptr >= #{r_ptr}", - (width + 1))

  # return count of destroyed nodes
  n_destroyed
end

#root? ⇒ Boolean

Boolean Methods

Returns:

  • (Boolean) 


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# File 'lib/fast_tree/model.rb', line 252

def root?
  self.l_ptr == 0
end

#width ⇒ Object 



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# File 'lib/fast_tree/model.rb', line 243

def width
  r_ptr - l_ptr
end