Module: HasShortestPath::ClassMethods

Defined in:
lib/has_shortest_path.rb

Instance Method Summary collapse

Instance Method Details

#has_shortest_path(options = {}) ⇒ Object

has_shortest_path defines a class as an edge in a graph

  • via: the class’s accessor for edges that it is connected to

  • weighted_with: the class’s accessor for the weight variable

  • through: the intermediate model that contains the weight (this is the vertex model)



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# File 'lib/has_shortest_path.rb', line 18

def has_shortest_path options = {}
  cattr_accessor :shortest_path_opts
  cattr_accessor :weighted_array
  
  self.shortest_path_opts = options
  
  raise "has_shortest_path requires the arguments :via, :weighted_with, and :through." if shortest_path_opts[:via].nil? || shortest_path_opts[:through].nil? || shortest_path_opts[:weighted_with].nil?
  
  # Weight of the vertex origination.destinations[1] => origination.connections[1].cost
  # Set up a method like 'weighted_destinations' that will return an array of all of the edges we have a vertex to,
  # with each edge having the weight from this edge to that edge.
  attr_accessor shortest_path_opts[:weighted_with]
  self.weighted_array = "weighted_#{self.shortest_path_opts[:via].to_s}".to_sym
  define_method(weighted_array) do
    self.send(shortest_path_opts[:via]).enum_for(:each_with_index).map { |dest, i| dest.cost = self.send(shortest_path_opts[:through])[i].cost; dest }
  end
  
end