Ruby is a popular, dynamic scripting language that aims to "feel natural to programmers"and give users the"freedom to choose" among many different ways of doing the same thing. While this arguably makes programming in Ruby easier, it makes it hard to build analysis and transformation tools that operate on Ruby source code. In this paper, we present the Ruby Intermediate Language (RIL), a Ruby front-end and intermediate representation that addresses these challenges. Our system includes an extensible GLR parser for Ruby, and an automatic translation into RIL, an easy-to-analyze intermediate form. This translation eliminates redundant language constructs, unravels the often subtle ordering among side effecting operations, and makes implicit interpreter operations explicit in its representation. We demonstrate the usefulness of RIL by presenting a simple static analysis and source code transformation to eliminate null pointer errors in Ruby programs. We also describe ...
Michael Furr, Jong-hoon (David) An, Jeffrey S. Fos