feat(linter/plugins): add meta property to rules

apps/oxlint/src-js/plugins/context.ts

@@ -1,3 +1,5 @@
+import type { RuleMeta } from './types.ts';
+
 // Diagnostic in form passed by user to `Context#report()`
 interface Diagnostic {
   message: string;
@@ -64,6 +66,8 @@ interface InternalContext {
   filePath: string;
   // Options
   options: unknown[];
+  // Rule metadata
+  meta: RuleMeta;
 }
 
 /**
@@ -80,12 +84,13 @@ export class Context {
    * @class
    * @param fullRuleName - Rule name, in form `<plugin>/<rule>`
    */
-  constructor(fullRuleName: string) {
+  constructor(fullRuleName: string, meta: RuleMeta) {
     this.#internal = {
       id: fullRuleName,
       filePath: '',
       ruleIndex: -1,
       options: [],
+      meta,
     };
   }
 

apps/oxlint/src-js/plugins/load.ts

@@ -1,7 +1,7 @@
 import { Context } from './context.js';
 import { getErrorMessage } from './utils.js';
 
-import type { AfterHook, BeforeHook, Visitor, VisitorWithHooks } from './types.ts';
+import type { AfterHook, BeforeHook, RuleMeta, Visitor, VisitorWithHooks } from './types.ts';
 
 const ObjectKeys = Object.keys;
 
@@ -21,10 +21,12 @@ export interface Plugin {
 export type Rule = CreateRule | CreateOnceRule;
 
 interface CreateRule {
+  meta?: RuleMeta;
   create: (context: Context) => Visitor;
 }
 
 export interface CreateOnceRule {
+  meta?: RuleMeta;
   create?: (context: Context) => Visitor;
   createOnce: (context: Context) => VisitorWithHooks;
 }
@@ -66,6 +68,9 @@ interface PluginDetails {
   ruleNames: string[];
 }
 
+// Default rule metadata, used if `rule.meta` property is empty.
+const emptyRuleMeta: RuleMeta = {};
+
 /**
  * Load a plugin.
  *
@@ -113,7 +118,20 @@ async function loadPluginImpl(path: string): Promise<PluginDetails> {
     const ruleName = ruleNames[i],
       rule = rules[ruleName];
 
-    const context = new Context(`${pluginName}/${ruleName}`);
+    // Validate `rule.meta` and convert to object with standardized shape
+    // (all properties defined with default values if not supplied)
+    let ruleMeta = rule.meta;
+    if (ruleMeta == null) {
+      ruleMeta = emptyRuleMeta;
+    } else {
+      if (typeof ruleMeta !== 'object') throw new TypeError('Invalid `meta`');
+      // TODO: Validate and conform individual properties of `meta` once they're supported
+      ruleMeta = emptyRuleMeta;
+    }
+
+    // Create `Context` object for rule. This will be re-used for every file.
+    // It's updated with file-specific data before linting each file with `setupContextForFile`.
+    const context = new Context(`${pluginName}/${ruleName}`, ruleMeta);
 
     let ruleAndContext;
     if ('createOnce' in rule) {

apps/oxlint/src-js/plugins/types.ts

@@ -39,3 +39,9 @@ export interface EnterExit {
   enter: VisitFn | null;
   exit: VisitFn | null;
 }
+
+// Rule metadata.
+// TODO: Fill in all properties.
+export interface RuleMeta {
+  [key: string]: unknown;
+}