When I took a class in compilers, our first project was to read in a source file written in Pascal, and match up the appropriate tokens for the variables, static values, and operators. I would take a similar approach. Since you know how perl identifies variables, you can write a script that will look for scalars, lists, and hashes by searching for the appropriate variable, and capturing it along with all the text up to the next symbol separating the variable from the rest of the program. I'm assuming that your input is a program that is not obfuscated.