Implement Language Plugins

[nzakas]

This issue describes the implementation plan for eslint/rfcs#99, which will take place in several phases:

Phase 1: Implement external changes

• [x] https://github.com/estools/esquery/pull/139
• [x] https://github.com/estools/esquery/pull/140
• [x] Update eslint-scope ScopeManager to expose isNodejsScope() as public method

Phase 2: Implement backward-compatible changes

• [x] Implement SourceCode#getInlineConfig()
• [x] Implement SourceCode#getDisableDirectives()
• [x] Implement SourceCode#traverse()
• [x] Copy context.getAncestors() to SourceCode https://github.com/eslint/eslint/pull/17059
• [x] Copy context.getDeclaredVariables() to SourceCode https://github.com/eslint/eslint/pull/17059
• [x] Copy context.getScope() to SourceCode https://github.com/eslint/eslint/pull/17004
• [x] Copy context.markVariableAsUsed() to SourceCode https://github.com/eslint/eslint/pull/17086
• [x] Copy parserServices to SourceCode https://github.com/eslint/eslint/pull/17311
• [x] Create context.cwd to replace context.getCwd() https://github.com/eslint/eslint/pull/17106
• [x] Create context.sourceCode to replace context.getSourceCode() https://github.com/eslint/eslint/pull/17107
• [x] Create context.filename to replace context.getFilename() https://github.com/eslint/eslint/pull/17108
• [x] Create context.physicalFilename to replace context.getPhysicalFilename() https://github.com/eslint/eslint/pull/17111
• [x] Blog post encouraging people to switch to the new APIs

Phase 4: Deprecation of old APIs (v8.0.0)

• [x] Update RuleTester to warn about context.getAncestors()
• [x] Update RuleTester to warn about context.getDeclaredVariables()
• [x] Update RuleTester to warn about context.getScope()
• [x] Update RuleTester to warn about context.parserServices
• [x] Update RuleTester to warn about context.getCwd()
• [x] Update RuleTester to warn about context.getSourceCode()
• [x] Update RuleTester to warn about context.getFilename()
• [x] Update RuleTester to warn about context.getPhysicalFilename()

Phase 5: Removal of old APIs (v9.0.0)

• [x] Remove context.getAncestors()
• [x] Remove context.getDeclaredVariables()
• [x] Remove context.getScope()
• [x] Remove context.markVariableAsUsed()
• [x] Remove context.parserServices

Phase 6: Create JS language object

• [x] Create JS language object with parse() and createSourceCode()
• [x] Update flat config to have language option (also update default config to use JS language object)
• [x] Update Linter to call language object for parsing (fallback to JS language for eslintrc)
• [x] Update Linter to use SourceCode#getInlineConfig()
• [x] Update Linter to use SourceCode#getDisableDirectives()
• [x] Update Linter to use SourceCode#traverse()

Phase 7: Create @eslint/json package

• [x] Publish @eslint/json

Phase 8: Create @eslint/markdown package

• [x] https://github.com/eslint/markdown/issues/260

Phase 9: Ecosystem Updates

• [x] Document how to create languages
• [x] Update @types/eslint with language type definitions
• [x] Publish Code Explorer
• [ ] Publish blog post announcing Markdown/JSON and Code Explorer

Phase 10: Removal of old APIs (v10.0.0)

• [ ] Remove context.getCwd()
• [ ] Remove context.getSourceCode()
• [ ] Remove context.getFilename()
• [ ] Remove context.getPhysicalFilename()

[snitin315]

I can also help with phase 2, I can start with Copy context.markVariableAsUsed() to SourceCode. @nzakas Let me know if that's ok.

[nzakas]

@snitin315 markVariableAsUsed() is a bit complicated, so I'd prefer to keep that one. If you could do the next few items (cwd, sourceCode, filename, and physicalFilename) that would be a huge help.

[amareshsm]

@nzakas I can also help with some items (any of CWD, sourceCode, filename, and physicalFilename) if possible. Can you pls give some context?

[nzakas]

@amareshsm if you'd like to take a look at those four, this is the part of the code involved: https://github.com/eslint/eslint/blob/9d1b8fc60cc31f12618e58c10a2669506b7ce9bf/lib/linter/linter.js#L979-L1000

Basically, we want to create properties where there are currently methods, and then update all of the rules to use the properties instead of the methods.

[ollie-iterators]

Phase 1 is finished!!!

[ollie-iterators]

With https://github.com/eslint/eslint/pull/17086 merged, Copy context.markVariableAsUsed() to SourceCode should be checked off

[mdjermanovic]

I'll work on parserServices.

[ollie-iterators]

With https://github.com/eslint/eslint/pull/17107 merged, Create context.sourceCode to replace context.getSourceCode() should be checked off

[nzakas]

@ollie-iterators it seems like you enjoy tracking our tasks, do you have any interest in becoming more involved with the project?

[nzakas]

I'm working on getInlineConfig next.

Edit: Okay, this is a lot more complicated than I realized initially. This may take a while and require some design changes.

[ollie-iterators]

@ollie-iterators it seems like you enjoy tracking our tasks, do you have any interest in becoming more involved with the project?

I haven't thought about that. I might be interested in that.

[nzakas]

@ollie-iterators cool. If you want to discuss, swing by Discord and we'd be happy to chat.

[mdjermanovic]

• Copy parserServices to SourceCode

I'm working on this now.

parserServices actually already exists on SourceCode, so the task is only to update documentation and tests.