Splint rambling: Clojure Parsers

I want another parser because I want access to comments. Without comments, I can't parse magic comments, meaning I can't enable or disable rules inline, only globally. That's annoying and not ideal. However, every solution I've dreamed up has some deep issue.

All times below are about parsing the 8.5k lines in clojure/core.clj.

• Edamame is our current parser and it's quite fast (40-60ms) but it drops comments. I've forked it to try to add them, but that would mean handling them in every other part of the parser, such as syntax-quote and maps and sets, making dealing with those objects really hard.

• Rewrite-clj is much slower (180ms) only exposes comments in the zip api, meaning I have to operate on the zipper objects with zipper functions (horrible and slow). It's nice to rely on Clojure built-ins instead of (loop [zloc zloc] (z/next* ...)) nonsense.

• parcera looked promising, but the pre-processing in parcera/ast is slow (240ms) and operating on the Java directly is deeply cumbersome. The included grammar also makes some odd choices and I don't know ANTLR4 well enough to know how to fix them (such as including the : in keyword strings). And maybe this isn't such a big deal but matching against strings is annoying. Means I'm writing something other than Clojure code.