[wladimir]

Yeah, you'd likely need some other way to refer so a position in the code than the line number. Maybe an anchor (like html) or a path in the syntax tree.

[cstuder]

These tools already exist: JavaScript tools like minfiers or CoffeeScript can generate source maps which map code lines from one format to code lines in another format.

http://www.html5rocks.com/en/tutorials/developertools/source...

[zalew]

but they are used for debugging, not bi-directional transformation between two incompatible sources.