Investigate using regexpp Instead of regexp-to-ast

[bd82]

• https://github.com/mysticatea/regexpp

• Is it more complete (e.g. unicode flag support).
• Performance?
• Runs in the browser / IE ?
• Which versions of node.js are supported?

[bd82]

I am not sure migration would be worth the effort.
It does not seem like maintaining regexp-to-ast requires too much effort.

[bd82]

Now that several new regExp features need to be supported (lookbehind/named capture groups)
It may be worth re-evaluating this.

It could also be evaluated in terms of performance easily as there is a (minimal) cold start benchmark now.

[bd82]

Had another quick look, This seems even more interesting to examine as:

• regexpp is still actively maintained.
• regexpp has no deps
• NodeJS V8.0.0 is supported
• It is 2020, perhaps it is time to ditch IE11 support instead of worrying about compatibility...

[bd82]

Performance of regexpp seems very similar to regexp-to-ast

regexp-to-ast Benchmark
Current version x 10,999 ops/sec ±0.77% (91 runs sampled)
regexpp x 11,116 ops/sec ±0.50% (93 runs sampled)
Fastest is regexpp,Current version

[bd82]

The regexpp does not seem to be well maintained at this time, perhaps the plans for swapping it out should be shelved.

[mattbishop]

Actually it seems pretty active compared to regexp-to-ast. Latest release June 14, 2021 vs Dec 19, 2019.

Also, and crucially, regexpp supports unicode escape sequences and groups. This is a must-have here in 2021!

[bd82]

Hi @mattbishop

I tried to recall what were my previous issue with regexpp
and rediscovered this previous blocker issue I opened more than a year ago.

• RegExpVisitor class is not exported mysticatea/regexpp#12
• (which I also provided a PR to fix...).

I'd still prefer to use a 3rd party library, but this means I need to find a way to patch it.

[bd82]

It may be possible to combine https://www.npmjs.com/package/patch-package with "bundledDependencies" to resolve (patch-hack) regexpp

[mattbishop]

Would it be hard to create a PR? I am assuming you have already forked regexpp. If you haven't I can put one together.

…

On Thu, Oct 7, 2021 at 12:30 PM Shahar Soel ***@***.***> wrote: It may be possible to combine https://www.npmjs.com/package/patch-package with "bundledDependencies" to resolve (patch-hack) regexpp — You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub <#777 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AACY3BOADTUJGYSDNZELKA3UFXYNXANCNFSM4FJQG3MQ> .

[bd82]

Would it be hard to create a PR? I am assuming you have already forked

I created one over a year ago...

• fix: export RegExpVistor at runtime. mysticatea/regexpp#13

That is why I need some hack to apply the patch as a consumer 😄

[bd82]

Assuming an hack is possible, the bigger work would the integration of regexpp instead of regexp-to-ast
I started this a while ago, to be honest I don't recall the status it is in

• https://github.com/Chevrotain/chevrotain/tree/regexpp

[mattbishop]

I pinged the regexpp maintainer and asked them to merge your request. If they don't then it might be easier to publish a different version with this change, along with others in the PR list, to suit Chevrotain. You will likely find other things that need attention too.

…

On Thu, Oct 7, 2021 at 1:16 PM Shahar Soel ***@***.***> wrote: Assuming an hack is possible, the bigger work would the integration of regexpp instead of regexp-to-ast I started this a while ago, to be honest I don't recall the status it is in - https://github.com/Chevrotain/chevrotain/tree/regexpp — You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub <#777 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AACY3BLUKYT4OWR6E355EDLUFX52LANCNFSM4FJQG3MQ> .

[bd82]

I am a little conflicted to be honest.

On one hand it would be very nice to have a blackbox providing all the regexp parsing needs.
On the other hand:

• regexpp does not actually provide all the needed APIs
• It does not seem to be actively maintained.

Maybe I should instead focus on updating regexp-to-ast to most modern regexp syntax.
and maybe even make it part of this monorepo to reduce maintenance overhead.
It is quite possible that updating regexp-to-ast to modern ECMAScript spec would require similar effort to refactoring Chevrotain to use regexpp...

[mattbishop]

Well it is nicer to have control of such an important lib. If you move it into the monorepo then it can stay in sync easier. Is anyone outside of chevrotain using it?

[bd82]

There are a handful of dependents.

• https://www.npmjs.com/browse/depended/regexp-to-ast

But they can still consume it if I move it to @chevrotain/regexp-to-ast package.
At the cost of losing meaningful semantic versioning numbers.

anyhow I am closing this in favor of #1670
When I get around to attempting to modernize the regexp support
I'll re-evaluate the current status and make a decision.