haste-map: Support extracting dynamic imports

[SimenB]

Summary

Support import('some-module') when building up a dependency tree within jest-haste-map.

Test plan

Assertion added

[thymikee]

nice!

[thymikee]

Not sure if we care, but this pass:

import(`${a}-b`)

[SimenB]

it only checks for ' and ", same as with the existing ones. We probably should support backticks as well

[cpojer]

Very nice! Can you do a follow-up to add backtick support? Note that we only want static dependencies so we are looking for:

import(`banana`)

// But not:
import(`${apple}`);

cc @mjesun I just realized we run multiple regexes. This is run on every single file to extract deps, so could be a major factor in cold start time. What do you think would happen if we merged the regexes into a single one and call .replace only a single time? Alternatively, @qfox built a fast parser for static deps at FB, I wonder if it's slower or faster than what we have here.

[SimenB]

combining into a single regexp would make my (currently not pushed) haste.moduleImportPatterns config simpler to implement as well. What I currently have (ish, from memory) is a Object.values(replacePatterns).concat(extraPatterns).forEach(pattern => source.replace(pattern, addDependency)). I bet that would make it even worse :P My only optimisation-plan was to merge the patterns in normalize instead of in the extractRequires function. Smooshing (:D) into a single regex seems cleaner, though.

Can you do a follow-up to add backtick support?

I'll see what I can do, my regex-fu is really weak, though.

[mjesun]

@cpojer Yup, this should speed up stuff, because of a) only parsing once and b) making the RegExp state machine to avoid one use case when we are already in another one. I'll check later.

[github-actions]

This pull request has been automatically locked since there has not been any recent activity after it was closed. Please open a new issue for related bugs.
Please note this issue tracker is not a help forum. We recommend using StackOverflow or our discord channel for questions.