bug in CommonTreeNodeStream

[ohm314]

Dear Kyle,

First of all, thanks for writing this great code!

I think I've stumbled across a little bug in your target code though. I believe that the CommonTreeNodeStream should expose the @last_marker instance variable via an attr_reader. This is needed when tree grammars generate DFAs. The initialize_dfas method calls @input.rewind(@input.last_marker, false) which can only work if last_marker is accessible for CommonTreeNodeStream.

example, taken from generated tree parser ruby code:

      @dfa1 = DFA1.new( self, 1 ) do |s| 
        case s
        when 0
          look_1_2 = @input.peek
          index_1_2 = @input.index
          @input.rewind( @input.last_marker, false )
          s = -1

Another possibility is to fix the the generated parser code to call @input.rewind without arguments, since last_marker is the default argument of this method.

Thanks,

omar

PS. here is a patch, I don't know how to attach a file (or what is the proper github way)

--- a/orig/tree.rb
+++ b/fixed/tree.rb
@@ -1107,6 +1107,8 @@ class CommonTreeNodeStream
     return @last_marker
   end

+  attr_reader :last_marker
+  
   def release( marker = nil )
     # do nothing?
   end