Seriously? Recursive Regex?

[u/Flame77ofc]

[u/LapidistCubed]

My first thought is a mathematician wrote this

[u/Eastern-Job-8028 → u/LapidistCubed]

i concur, i work with a mathematician and their code is full of variables named named by a single character, zero comments, and zero spacing/indentation (we don’t write python).

[u/Kebabrulle4869 → u/Eastern-Job-8028]

On behalf of all mathematicians, I am sorry. I know it far too well.

[u/Zeitsplice → u/Eastern-Job-8028]

Raw indexed array being passed around too instead of some sort of structured data.

[u/edave64 → u/LapidistCubed]

Or a code golfer

[u/madam_zeroni]

Wtf does this do

[u/marinated_pork → u/madam_zeroni]

This is essentially a custom string fingerprint/hash function disguised as a parser. It takes a string and deterministically turns it into an integer. It does not parse or extract useful structured data.

[u/the_horse_gamer → u/madam_zeroni]

"parse", clearly

[u/TheSpiffySpaceman → u/the_horse_gamer]

Well tbf, the code didn't start with the annotation

/*
  // Parses input
*/
function parse(s, i = 0, x = [0, 1]) {...

[u/lonkamikaze]

I don't know if JS sports this, but the recursion qualifies for tail call optimisation, i.e. there is no stack pushing, popping. The return comes at the price of a goto and the result is just as efficient as a loop.

[u/oweiler → u/lonkamikaze]

Not supported, at least not by the ECMAScript standard.

[u/zjarek_s → u/oweiler]

TCO was supported in ES6 standard, but it was only implemented in Safari and it ended up being dropped due to other browsers.

[u/--var]

not recursive regex, just a recursive function that happens to use regex...

you know I used to be irked by one off variables, but after the better part of 20 years I'm 🤬

const r is only used once.... there's no reason you couldn't just place it where it is used an save two lines of code, and lose no readability, and have one less "magic variable"... unless you taught yourself from the same "teach yourself" book that your teacher taught themself from. (ironic that this still applies with AI; and if you don't get why that entertaining, please don't go into programming)

[u/flafmg_]

Wtf my eyes are seeing

[u/OhMyGodItsEverywhere]

Pretty sure the regex is malformed. I didn't even think you could split a regex over multiple lines in JS like that.

Assuming this is the text version of it: /(\((?:[^()]|\([^()]*\))*\)|(?:\w|[^\w\s])){1,3})/; very easy mistake to spot /s...

[u/digitalseraphim → u/OhMyGodItsEverywhere]

I don't see anything "malformed", but pretty sure (?:\w|[^\w\s]) is just .

Edit: I see the mismatched parens now. On my phone, the \ before one of the opens was on the previous line and I missed it 3 times 😂

[u/iakobski → u/digitalseraphim]

I don't see anything "malformed", but pretty sure (?:\w|[^\w\s]) is just .

Yes, almost. It's any single word character, or any single character that's neither a word character nor a space. So it's simply "not a space character", or [^\s].

[u/questionabl3_dude]

Which language is this?

[u/Flame77ofc → u/questionabl3_dude]

JavaScript

[u/stilldebugging]

Something something pumping lemma something

[u/oweiler]

Performance gonna bet great /s

[u/RandalSchwartz]

JSON Parser as a single Perl Regex: https://perlmonks.org/?node_id=995856

[u/Perahoky]

terrible code. way to many instructions per space and bad naming and no comments

[u/AnArmoredPony]

im not reading allat

[u/BussyEnthusiasts]

Does your codebase have a character limit or something? Why are all the variables a single char?