Cache parsed path mapping patterns

[amcasey]

If a project has many of them (e.g. 1800), parsing the patterns repeatedly can take up a lot of time.

Specifically, getOwnKeys and hasZeroOrOneAsteriskCharacter were showing up as self-time hotspots.

[sheetalkamat]

Why did we remove the assert or requirement that users of this have this checked already?

[amcasey]

The check was duplicated between the caller and the assert (none needed it for other reasons - they were just doing it to satisfy this requirement). I didn't think the requirement made the API conceptually clearer or the implementation simpler - on the contrary, I thought it was preferable to gather all the checks into a single function.

[amcasey]

Perhaps your question was "what happened to the proper error?". It's still there - an undefined result now indicates that an error should be reported.

[amcasey]

Force push is a rebase onto master. Updates to follow.

[amcasey]

@typescript-bot pack this

[typescript-bot]

Heya @amcasey, I've started to run the tarball bundle task on this PR at 0435303. You can monitor the build here.

[typescript-bot]

Hey @amcasey, I've packed this into an installable tgz. You can install it for testing by referencing it in your package.json like so:

{
    "devDependencies": {
        "typescript": "https://typescript.visualstudio.com/cf7ac146-d525-443c-b23c-0d58337efebc/_apis/build/builds/103950/artifacts?artifactName=tgz&fileId=5B3FB4B8589F2D1B2AB57D830882879C2CC6FD618829A38998245D6627FCD24802&fileName=/typescript-4.4.0-insiders.20210526.tgz"
    }
}

and then running npm install.

---

There is also a playground for this build and an npm module you can use via "typescript": "npm:@typescript-deploys/pr-build@4.4.0-pr-44078-3".;