lib/graph.njae/vertex.rb

   1 # A simple graph library
   2
   3 module GraphNjae
   4   # A vertex in a graph. The edge can have arbitrary attributes,treated as
   5   # method names.
   6   class Vertex < OpenStruct
   7     def initialize(values = {})
   8       super(values)
   9       self.edges = []
  10       self
  11     end
  12
  13     # Connect this vertex to another, creating an Edge to do so, and returning
  14     # the Edge
  15     def connect(other, edge_attributes = {})
  16       e = Edge.new edge_attributes
  17       e << self << other
  18       # self.edges << e
  19       # other.edges << e unless self === other
  20       e
  21     end
  22
  23     # Connect this vertex to another, creating an Edge to do so, and returning
  24     # this Vertex
  25     def <<(other)
  26       connect(other)
  27       self
  28     end
  29
  30     # Return the set of neighbouring vertices
  31     def neighbours
  32       #vertices = self.edges.map {|e| e.vertices}.flatten
  33       #vertices_to_me = vertices.select {|v| v == self}
  34       #other_vertices = vertices.select {|v| v != self}
  35       #(vertices_to_me[1..-1] || []) + other_vertices#
  36       self.edges.map {|e| e.vertices.take_while {|v| v != self} +
  37                       e.vertices.drop_while {|v| v != self}[1..-1]}.flatten
  38     end
  39
  40     def to_s
  41       '<V: ' + self.name.to_s + '>'
  42     end
  43
  44     def to_dot(opts = {})
  45       if block_given?
  46         yield self
  47       else
  48         dot = self.object_id.to_s
  49         if opts.size > 0
  50           dot << ' {'
  51           dot << opts.keys.map { |k|
  52             (k.to_s + ' = "' + self.instance_eval(opts[k].to_s).to_s) + '"'
  53                         }.join(', ')
  54           dot << '}'
  55         end
  56         dot << ';'
  57       end
  58     end
  59
  60   end
  61 end