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refactor: leverage Prettier's AstPath and comment attachment #731

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@jtkiesel jtkiesel commented Apr 27, 2025

What changed with this PR:

The printer is totally refactored to leverage Prettier's own AstPath and comment attachment to reduce the amount of work done by our own code (including a reduction of ~1700 lines of code). Also improved type safety a bit, specifically by making CstElement a union type of IToken and all possible CstNode types, and in general aligned formatting a bit closer to Prettier's own formatting for JavaScript/TypeScript (one of those happens to be #720).

Because I wanted to prove that it would be easy to resolve issues with comments after refactoring to use Prettier's built-in comment attachment, I also integrated the implementation for #534, while fixing the comment issues I was having in #716.

Because this PR directly leverages Prettier's printing library, there are a few other issues that I have not yet verified, but may be able to be closed with the merge of this PR, including #487 and #660.

Because I renamed some files from *.js to *.ts, the full diff of the commits in this PR makes it appear as though the *.js files were deleted, but I renamed them in the 1st commit to preserve their git history. Because of this, we should avoid squashing this PR's commits when merging, if we want to keep that history.

Something to consider: I removed the java-parser package's custom comment attachment capability, and instead simply attach all comments to the comments field of the root node, which is what Prettier expects to allow it to move the comments to the appropriate nodes itself. This would be considered a breaking change to the java-parser package, and so should probably result in a major version increment, if we were to keep this change (though I don't really know how we've been treating breaking changes to the parser in the past). If instead, we determine that we wish to continue supporting our own custom comment attachment in the parser itself, then we could bring it back, and simply make it configurable to disable it. I'm open to either approach, but would obviously prefer to gut the code and reduce our maintenance burden if we can.

Example

Options

--experimental-operator-position start

Input

class Example {

  void example() {
    var rotateX =
      (RANGE / rect.height) * refY -
      (RANGE / 2) * getXMultiplication(rect.width);
  }

  void nestedForStatement() {
    for (SomeClass<?> elem : elements) for (SomeClass<
      ?
    > elem : elements) for (SomeClass<?> elem : elements) doSomeThing();
  }
}

Output

class Example {

  void operatorPositionStart() {
    var rotateX =
      (RANGE / rect.height) * refY
      - (RANGE / 2) * getXMultiplication(rect.width);
  }

  void nestedForStatement() {
    for (SomeClass<?> elem : elements)
      for (SomeClass<?> elem : elements)
        for (SomeClass<?> elem : elements) doSomeThing();
  }
}

Relative issues or prs:

Closes #534
Closes #592
Closes #720
Obsoletes #595
Obsoletes #716
Obsoletes #719

@jtkiesel jtkiesel force-pushed the refactor/prettier-path-and-comment branch 2 times, most recently from f19949b to 04c9d2d Compare May 2, 2025 23:50
@DanielFran DanielFran added $$ bug-bounty $$ https://www.jhipster.tech/bug-bounties/ $300 labels May 3, 2025
@jtkiesel jtkiesel force-pushed the refactor/prettier-path-and-comment branch 5 times, most recently from d6a2c1c to 8f906c6 Compare May 5, 2025 04:58
@jtkiesel jtkiesel force-pushed the refactor/prettier-path-and-comment branch from 8f906c6 to 84b3149 Compare May 11, 2025 07:04
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Hello @jtkiesel ! Great work also here. It seems that it will certainly lessen the maintaining burden and ease comments handling.

I didn't had the time to fully review the MR this morning (there are quite some changes). I think I should be able to continue (and hopefully finish it) before Tuesday evening.

Let me know if you do not agree with some of the comments, we can discuss them ;)

@jtkiesel jtkiesel force-pushed the refactor/prettier-path-and-comment branch from 84b3149 to cbce061 Compare May 11, 2025 20:13
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jtkiesel commented May 11, 2025

Thank you for taking the time to review, @clementdessoude! I've resolved/responded to all your comments, happy to continue discussing as well. I'll look forward to the rest of your review! Thanks again for taking the time, I know it's a large PR. 😅

@jtkiesel jtkiesel force-pushed the refactor/prettier-path-and-comment branch from cbce061 to 8f7637c Compare May 17, 2025 05:26
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Just made some minor changes to improve the types on both the parser and the printer. Made it clear via the types that only the root node from the parser now contains comments, and added comments to the types on the printer side (where Prettier is now attaching them to the appropriate nodes). Also renamed some types/functions in the printer, because "node" vs "token" was a bit confusing due to Prettier using "node" to describe all elements of the AST, so I went with "non-terminal" and "terminal".

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I still have a few files to review, but I made some progress 😆

@jtkiesel jtkiesel force-pushed the refactor/prettier-path-and-comment branch from 8f7637c to ae983d9 Compare May 19, 2025 05:41
@jtkiesel jtkiesel requested a review from clementdessoude May 19, 2025 05:53
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wildcard type variable surrounded by line breaks Formatting not stable with comment in if statement Wrap before binary operators
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