New: Implement DotCompat class

[nzakas]

This implements a new DotCompat class that translates between the ESLintRC-style configs and the new-style (which I'm now calling the "dot config" style). There are four main methods:

• config() - translates an entire config
• env() - translates only environments
• extends() - translates only extends field
• plugins() - loads plugins

I think I got all of the cases, but do let me know if it seems like I missed anything.

[nzakas]

Just pushed a new version where the contents of files and ignores can be either strings or functions that accept an absolute path as their first argument. This makes the solution less pure than I had hoped it would be, but ultimately, this will give us complete backwards compatibility with ESLintRC.

Still one open comment I need to investigate regarding the languageOptions block.

[btmills]

The old config system is complex, so there are probably edge cases that this doesn't handle yet. I'm satisfied that this is good enough to address the vast majority of use cases. We can let actual usage reveal what other cases, if any, this needs to handle.

[dimitropoulos]

hey @nzakas is there anywhere (including source code) you could point me to that could tell me a little more about how this new "dot config" format works? I looked around for a bit but couldn't find much - my apologies if I missed something.

[nzakas]

eslint/eslint#13481