testing cyclic graphs

lib/awkward/visitor.rb

@@ -1,41 +1,74 @@
 module Awkward
   class Visitor
-    Node = Struct.new :object
+    class Node < Struct.new :object # :nodoc:
+      def name
+        object.class.name
+      end
+
+      private
+      def escape string
+        string.gsub '"', '\"'
+      end
+    end
+
     Edge = Struct.new :name, :left, :right
 
-    attr_reader :nodes
     attr_reader :edges
 
     def initialize
       @nodes     = []
+      @stack     = []
       @edges     = []
       @callstack = []
       @seen      = {}
     end
 
+    def nodes
+      @seen.values
+    end
+
     def accept o
-      return cycle(o) if @seen[o.object_id]
+      return connect(@stack.last, @seen[o.object_id]) if @seen.key? o.object_id
 
       node = Node.new o
 
       @seen[o.object_id] = node
 
-      @nodes.push node
+      connect(@stack.last, node) unless @callstack.empty?
 
-      cycle o
+      @stack.push node
 
       send "visit_#{o.class.name.gsub('::', '_')}", o
+
+      @stack.pop
     end
 
     def to_dot
+      dot = <<-eodot
+digraph "Graph" {
+node [width=0.375,height=0.25,shape=box];
+      eodot
+
+      nodes.each do |node|
+        dot.concat <<-eonode
+        #{node.object_id} [label="#{node.name}"];
+        eonode
+      end
+
+      edges.each do |edge|
+        dot.concat <<-eoedge
+        #{edge.left.object_id} -> #{edge.right.object_id} [label="#{edge.name}"];
+        eoedge
+      end
+      dot + "}"
     end
 
     private
 
     def visit_Hash o
-      o.each do |k,v|
-        edge(:key) { accept k }
-        edge(:value) { accept v }
+      o.each_with_index do |(k,v),i|
+        edge("key: #{i}") { accept k }
+        edge("value: #{i}") { accept v }
       end
     end
 
@@ -55,14 +88,8 @@ def edge sym
       @callstack.pop
     end
 
-    def escape string
-      string.gsub '"', '\"'
-    end
-
-    def cycle o
-      if last = @nodes.last && @callstack.last
-        @edges << Edge.new(@callstack.last, last.object_id, o.object_id)
-      end
+    def connect from, to
+      @edges << Edge.new(@callstack.last, from, to)
     end
   end
 end

test/test_awkward.rb

@@ -19,4 +19,27 @@ def test_edges
     awkward.accept @tree
     assert_equal 7, awkward.edges.length
   end
+
+  def test_edges_have_nodes
+    awkward = Awkward::Visitor.new
+    awkward.accept @tree
+    nodes = awkward.edges.map { |e| [e.left, e.right] }.flatten.uniq
+    expected = awkward.nodes
+    assert_equal expected.sort_by(&:object_id), nodes.sort_by(&:object_id)
+  end
+
+  def test_to_dot
+    awkward = Awkward::Visitor.new
+    awkward.accept @tree
+    awkward.to_dot
+  end
+
+  def test_cyclic
+    foo = {}
+    foo[:a] = { :b => { :c => foo } }
+
+    awkward = Awkward::Visitor.new
+    awkward.accept foo
+    awkward.to_dot
+  end
 end