Wednesday, March 24, 2010

JSHydra and ASTs

One goal I've had for a while with respect to JSHydra was to have it actually spit out an easy-to-understand AST, akin to the kind of AST you get from Pork, as opposed to the parse tree from SpiderMonkey. After reading around in a fashion, I've written a postprocessing script to do so.

The basic idea for the output format is along the lines of the JsonML AST format, with a mixture of pork and "I think this is what's happening" to top it off. The actual ["Type", {}, child1, child2] format I quickly gave up using because it proves cumbersome to look at; in the interest of keeping something akin to the Pork format, I moved to a more ad-hoc format, which loosely follows the visitor pattern they mention.

I've added this output format to the WebJSHydra reader (yes, it is a copy-paste in part of the webpork code), so you can play with it to your heart's content. Just don't make it large. It also doesn't support E4X, and I'm not entirely assured of its correctness. Also, I don't support the visitor yet, nor do I have a C or C++ version of the AST for static analysis tools.


arshad'sblog said...
This comment has been removed by the author.
arshad'sblog said...

Need to know whether there is a utility which provides JavaScript program, given ast provided by jshydra. It would be reverse of what is provided to process_js' as first argument.

Joshua Cranmer said...

decompile.js provides a functional decompiler, although it doesn't work on all inputs.