feat: add support for getLocFromIndex and getIndexFromLoc

[lumirlumir]

Prerequisites checklist

• I have read the contributing guidelines.

What is the purpose of this pull request?

Working in progress.

What changes did you make? (Give an overview)

Related Issues

Is there anything you'd like reviewers to focus on?

Prerequisite

• feat: add support for getLocFromIndex and getIndexFromLoc rewrite#212
• perf: improve time complexity of getLocFromIndex eslint#19782

[nzakas]

Before you get too far on this, is this function currently needed? As discussed in eslint/rewrite#166, this is an expensive operation and I don't think we want to incorporate it unless we absolutely need it.

[lumirlumir]

@nzakas

I thought this method could replace the findOffsets method used throughout the rules in @eslint/markdown, so I saw it as both a refactor and a new feature.

It’s currently used in two rules, and I use this kind of logic in my own rules as well (for context, please see https://github.com/lumirlumir/npm-eslint-plugin-mark/blob/main/packages/eslint-plugin-mark/src/core/ast/text-handler/text-handler.js).

If this feature isn’t necessary for now, I’ll go ahead and close it.

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(If it is fine, I would like to keep exploring and look for a more performant solution.)

[nzakas]

@lumirlumir ah, I forgot about that. Gotcha. 👍 If you're going to go through the trouble of investigating, then I'd suggest doing it on TextSourceCodeBase so every project can benefit.

[lumirlumir]

@nzakas Thanks for understanding!

I’ll keep this PR open for now, move on to implementing TextSourceCodeBase, and then come back to this one afterward.

Can I assign myself for the issue I've created? eslint/rewrite#166

[nzakas]

Go ahead.

[nzakas]

The other thing to keep in mind is that findOffsets() is not always used from the beginning of the document. Like in this case:

markdown/src/rules/no-html.js

Line 71 in cb5a956

const { lineOffset, columnOffset } = findOffsets(

It's finding the offset inside a given node's text.