ruby-in-ruby/crystal — pull request #1 by NigelThorne (2014-06-04 12:02:42+00:00)
Title: Auto Detect infinite loops

Hi, I forked Parslet to put in some infinite loop detection. Using that, I debugged your failing_test example.
I didn't fix up the test, just fixed the root cause.

If you just grab my fork of Parslet, you can see how it points you in the right direction.