lib/graph/edge.rb

   1 require 'ostruct'
   2
   3 # A simple graph library
   4
   5 module Graph
   6
   7   # An edge (or multiedge) in a graph. The edge can have arbitrary attributes,
   8   # treated as method names.
   9   #
  10   # Each connection is handled by a Graph::Connection object, so that each end
  11   # of the Edge can have it's own attributes.
  12   class Edge < OpenStruct
  13     def initialize
  14       super
  15       self.connections = []
  16       self
  17     end
  18
  19     # Connect this edge to a vertex
  20     def <<(other)
  21       c = Connection.new
  22       c.end = other
  23       self.connections << c
  24       self
  25     end
  26
  27     # Return the set of vertices this edge connects.
  28     def vertices
  29       self.connections.map {|c| c.end}
  30     end
  31
  32     # Return the connection object that joins this Edge to the specified Vertex
  33     def connection_at(vertex)
  34       self.connections.select {|c| c.end.equal?  vertex}.first
  35     end
  36   end
  37
  38   # A connection between an Edge and a Vertex.The connection can have arbitrary attributes,
  39   # treated as method names.
  40   class Connection < OpenStruct
  41     def initialize
  42       super
  43       self
  44     end
  45   end
  46 end