X-Git-Url: https://git.njae.me.uk/?a=blobdiff_plain;f=lib%2Fgraph.njae%2Fgraph.rb;h=acfc9e07e998ee3843aa19e990f7670d38a8bcce;hb=e3fe1f33fea019106289edfae4e7a32f3ba3e03b;hp=1da5297d1f74861b24ce417dc2ac6c0ff3181111;hpb=c34def40508c16cfc815fa02c8743d071491af7b;p=graph.njae.git

diff --git a/lib/graph.njae/graph.rb b/lib/graph.njae/graph.rb
index 1da5297..acfc9e0 100644
--- a/lib/graph.njae/graph.rb
+++ b/lib/graph.njae/graph.rb
@@ -7,8 +7,8 @@ module GraphNjae
   # A container for all the parts of a graph.  The graph can have arbitrary attributes,
   # treated as method names.
   class Graph < OpenStruct
-    def initialize
-      super
+    def initialize(values = {})
+      super(values)
       self.edges = Array.new
       self.vertices = Array.new
       self
@@ -16,12 +16,47 @@ module GraphNjae
     
     # Add a Vertex or Edge to the graph.
     def <<(other)
-      if other.class == Vertex
+      if other.class.ancestors.include? Vertex
         self.vertices << other
-      elsif
+      elsif other.class.ancestors.include? Edge
         self.edges << other
       end
       self
     end
-  end
+    
+    # Connects two vertices, creating and storing a new edge
+    # Also adds the vertices, unless they're already in the graph
+    def connect(vertex1, vertex2)
+      self.vertices << vertex1 unless self.vertices.include? vertex1
+      self.vertices << vertex2 unless self.vertices.include? vertex2
+      edge = Edge.new
+      self.edges << edge
+      edge << vertex1 << vertex2
+    end
+    
+    # Form a product graph of this graph and the other.
+    # Return the new graph.
+    def product(other)
+      product_graph = Graph.new
+      self.vertices.each do |v1|
+        other.vertices.each do |v2|
+          product_graph << Vertex.new({:g1_vertex => v1, :g2_vertex => v2})
+        end
+      end
+      self.edges.each do |e1|
+        e1_vertices = e1.vertices
+        other.edges.each do |e2|
+          e2_vertices = e2.vertices
+          source = product_graph.vertices.find {|v| v.g1_vertex == e1_vertices[0] and v.g2_vertex == e2_vertices[0]}
+          destination = product_graph.vertices.find {|v| v.g1_vertex == e1_vertices[1] and v.g2_vertex == e2_vertices[1]}
+          product_graph.connect source, destination
+          source = product_graph.vertices.find {|v| v.g1_vertex == e1_vertices[0] and v.g2_vertex == e2_vertices[1]}
+          destination = product_graph.vertices.find {|v| v.g1_vertex == e1_vertices[1] and v.g2_vertex == e2_vertices[0]}
+          product_graph.connect source, destination
+        end
+      end
+      product_graph
+    end
+    
+  end # class
 end