Module: Dag::Edges

Defined in:
lib/dag/edges.rb

Defined Under Namespace

Modules: EdgeInstanceMethods

Class Method Summary collapse

Instance Method Summary collapse

Class Method Details

.included(base) ⇒ Object 



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# File 'lib/dag/edges.rb', line 4

def self.included(base)
  base.send :include, EdgeInstanceMethods
end

Instance Method Details

#build_edge(ancestor, descendant) ⇒ Object

Class methods that extend the link model for both polymorphic and non-polymorphic graphs Returns a new edge between two points



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# File 'lib/dag/edges.rb', line 10

def build_edge(ancestor, descendant)
  source = self::EndPoint.from(ancestor)
  sink = self::EndPoint.from(descendant)
  conditions = self.conditions_for(source, sink)
  path = self.new(conditions)
  path.make_direct
  path
end

#create_edge(ancestor, descendant) ⇒ Object

Creates an edge between two points using save



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# File 'lib/dag/edges.rb', line 41

def create_edge(ancestor, descendant)
  link = self.find_link(ancestor, descendant)
  if link.nil?
    edge = self.build_edge(ancestor, descendant)
    return edge.save
  else
    link.make_direct
    return link.save
  end
end

#create_edge!(ancestor, descendant) ⇒ Object

Creates an edge between two points using save! Returns created edge



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# File 'lib/dag/edges.rb', line 53

def create_edge!(ancestor, descendant)
  link = self.find_link(ancestor, descendant)
  if link.nil?
    edge = self.build_edge(ancestor, descendant)
    edge.save!
    edge
  else
    link.make_direct
    link.save!
    link
  end
end

#direct?(ancestor, descendant) ⇒ Boolean

Alias for edge

Returns:

  • (Boolean) 


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# File 'lib/dag/edges.rb', line 116

def direct?(ancestor, descendant)
  self.edge?(ancestor, descendant)
end

#edge?(ancestor, descendant) ⇒ Boolean

Determines if an edge exists between two points

Returns:

  • (Boolean) 


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# File 'lib/dag/edges.rb', line 111

def edge?(ancestor, descendant)
  !self.find_edge(ancestor, descendant).nil?
end

#find_edge(ancestor, descendant) ⇒ Object

Finds an edge between two points, Must be direct



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# File 'lib/dag/edges.rb', line 20

def find_edge(ancestor, descendant)
  source = self::EndPoint.from(ancestor)
  sink = self::EndPoint.from(descendant)
  self.first :conditions => self.conditions_for(source, sink).merge!({direct_column_name => true})
end

#find_link(ancestor, descendant) ⇒ Object

Finds a link between two points



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# File 'lib/dag/edges.rb', line 27

def find_link(ancestor, descendant)
  source = self::EndPoint.from(ancestor)
  sink = self::EndPoint.from(descendant)
  self.first :conditions => self.conditions_for(source, sink)
end

#find_or_build_edge(ancestor, descendant) ⇒ Object

Finds or builds an edge between two points



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# File 'lib/dag/edges.rb', line 34

def find_or_build_edge(ancestor, descendant)
  edge = self.find_edge(ancestor, descendant)
  return edge unless edge.nil?
  return build_edge(ancestor, descendant)
end

#longest_path_between(ancestor, descendant, path = []) ⇒ Object

Finds the longest path between ancestor and descendant returning as an array



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# File 'lib/dag/edges.rb', line 67

def longest_path_between(ancestor, descendant, path=[])
  longest = []
  ancestor.children.each do |child|
    if child == descendant
      temp = path.clone
      temp << child
      if temp.length > longest.length
        longest = temp
      end
    elsif self.find_link(child, descendant)
      temp = path.clone
      temp << child
      temp = self.longest_path_between(child, descendant, temp)
      if temp.length > longest.length
        longest = temp
      end
    end
  end
  longest
end

#shortest_path_between(ancestor, descendant, path = []) ⇒ Object

Finds the shortest path between ancestor and descendant returning as an array



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# File 'lib/dag/edges.rb', line 89

def shortest_path_between(ancestor, descendant, path=[])
  shortest = []
  ancestor.children.each do |child|
    if child == descendant
      temp = path.clone
      temp << child
      if shortest.blank? || temp.length < shortest.length
        shortest = temp
      end
    elsif self.find_link(child, descendant)
      temp = path.clone
      temp << child
      temp = self.shortest_path_between(child, descendant, temp)
      if shortest.blank? || temp.length < shortest.length
        shortest = temp
      end
    end
  end
  return shortest
end