initial version externalized from salama

lib/sof/node.rb

@@ -0,0 +1,58 @@
+# We transform objects into a tree of nodes
+
+module Sof
+  #abstract base class for nodes in the tree
+  # may be referenced (should be a simple name or number)
+  class Node
+    include Util
+    def initialize ref
+      @referenced = ref
+    end
+    # must be able to output to a stream
+    def out io ,level
+      io.write "&#{@referenced} " if @referenced
+    end
+    def as_string(level)
+      io = StringIO.new
+      out(io,level)
+      io.string
+    end
+    attr_reader :referenced
+  end
+  
+  class SimpleNode < Node
+    def initialize data , ref = nil
+      super(ref)
+      @data = data
+    end
+    attr_reader :data
+    def out io , level
+      super(io,level)
+      io.write(data)
+    end
+  end
+  
+  class ObjectNode < Node
+    def initialize data , ref
+      super(ref)
+      @data = data 
+      @children = []
+    end
+    attr_reader   :children ,  :data
+    def add k , v
+      @children << [k,v]
+    end
+    def out io , level = 0
+      super
+      io.write(@data)
+      indent = " " * (level + 1)
+      @children.each_with_index do |child , i|
+        k , v = child
+        io.write "\n#{indent}"
+        k.out(io , level + 2)
+        io.write " "
+        v.out(io , level + 2)
+      end
+    end
+  end
+end