Parsing source code can be so easy…
...when you use the right programming language and environment.
After three days of learning Smalltalk, I changed the code editor's automatic code formatter (in the Squeak System Browser) by modifying some code in the AST classes. Squeak is really an awesome environment when you want to play around with your programming tools.
Compare: After four years of using Objective-C on GNUstep, I still couldn't figure out how to improve IDE support, because parsing is so much harder in languages like these (Java isn't better.).
I've seen a couple of programming languages and programming environments. Squeak really impresses me a lot.