Fix formatter

[ydaveluy]

Hello,

This PR addresses several issues in the current formatter implementation:

• Return only the necessary edits: This ensures that only the edits which actually change the document are returned, rather than all possible edits.

• Fix avoidOverlappingEdits: This change improves the removal of overlapping edits, ensuring they are handled correctly across multiple levels.

• Prevent formatting on the same line: This update prevents formatting actions from being applied to the same line if the previous node is hidden.

These improvements aim to enhance the accuracy and efficiency of the formatter. Please let me know if you have any questions or need further clarifications.

[cdietrich]

Can we double check if this won’t reintroduce https://github.com/eclipse-langium/langium/pull/1550/files #1469

[msujew]

Looks mostly good to me. Just one issue (on Windows systems, see below). Can you also please create a test case for that: You will need to manually invoke the Formatter service for that, and assert that no text edits are returned for a correctly formatted document (ideally with formattings that are doing newline or indentation).

[msujew]

@cdietrich I can't imagine this reintroducing #1362, but I also don't have a test case for this anymore. Do you still have one lying around and try it against this branch?

[cdietrich]

@msujew unfortunately i have no langium dev env available as linking will mess up everything.
do you have an idea how to try it less invasively?

[msujew]

@cdietrich You could add the test repo as a temporary part the examples of this branch. That way, npm should do the linking for you.

@ydaveluy There is a linting error, see https://github.com/eclipse-langium/langium/actions/runs/10387365742/job/28760687114?pr=1628

[cdietrich]

@msujew thx. looks good. formatter stays idempotent

[msujew]

@cdietrich Thanks for checking!