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.

More jshydra news

Taking a break from my ongoing series on pork, it's now time for an overdue update on jshydra.

First off, I have pushed Andrew Sutherland's changes (most of them, anyways) to my repo. These consist of the ability to push arguments, proper JS constructor handling (which I had locally but didn't commit for some reason I long forgot), and some minor comment handling fixes. I also never mentioned my JS inheritance divination work from way back in May. I also fixed a bug and finally got around to making TOK_* variables visible in JS, like the JSOP_* variables.

David Dahl has decided to use jshydra to find dead code in JS. That bug also has some discussion on how to run jshydra, as well as some work-in-progress files to grab JS information from the mozilla build system in a jshydra-friendly format.

Andrew Sutherland also used jshydra to generate documentation for TB. His blog posting does it more justice than I ever could.

Last night, I finally got around to creating an analogue of David Humphrey's Dehydra Web for JSHydra, predictably called JSHydra Web. As a note of caution, please don't upload your massive, 100+KB JS file for perusing: you'll find the output hard to read, and I don't want to overload the server.

As always, for more information on jshydra, you can either contact me by email (found on bugzilla), by IRC (most topical place of discussion is #static), or via the mozilla.dev.static-analysis newsgroup.

jshydra news

Since I happen to have some downtime thanks to the short space between college and a summer job, and some spare time with four wisdom teeth newly missing from my mouth, I have returned to work on jshydra. I am in the midst of simplifying the build structure for new or non-Mozilla hackers, and am also patching up one of the main scripts I have, the documentation-association script.

On Monday, May 11, 2008, at 1:00 PM EDT (10:00 AM PDT, or 1700 UTC), I will be holding in the #static IRC room for the benefit of users a "learn jshydra" day. You may of course ask me questions any time I'm actually on IRC (nick: jcranmer or derivatives thereof).

I hope to finish up the build structure by then and get a wiki article on the topic started as well. A feature request list is already starting, including the ability to take JS out from an HTML file. If you have others, communicate it to me somehow, and I'll stick it somewhere where I can remember it.

JSHydra

Over the past week or so, in between my myriads of projects, I managed to find time to revive a partially-completed tool called jshydra (properly capitalized as "JSHydra"). JSHydra, in both name and code, is derived from Dehydra and Treehydra: it is a static analyzer for JavaScript. I first decided that such a tool was needed when I was in the middle of a large refactoring of address book code.

The source code for jshydra can be found at my Mozilla user hg repo. Presently, it requires some hackery and file modifications to merely build the system. I use SpiderMonkey internal APIs (the parsing APIs, to be exact), so that's where most of the hackery comes into play.

For the time being, I'm probably going to put aside doing more work on jshydra, as I have more pressing work on my plate at this time. If you have any questions, feel free to contact me via IRC (handle: jcranmer (I should be in #mmgc)) or via my email address as listed in bugzilla.