perf(linter/plugins): use singleton for SourceCode

Author: overlookmotel

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

@@ -1,7 +1,8 @@
 import { getFixes } from './fix.js';
-import { SourceCode } from './source_code.js';
+import { SOURCE_CODE } from './source_code.js';
 
 import type { Fix, FixFn } from './fix.ts';
+import type { SourceCode } from './source_code.ts';
 import type { Node } from './types.ts';
 
 // Diagnostic in form passed by user to `Context#report()`
@@ -33,13 +34,11 @@ export const diagnostics: DiagnosticReport[] = [];
  * @param context - `Context` object
  * @param ruleIndex - Index of this rule within `ruleIds` passed from Rust
  * @param filePath - Absolute path of file being linted
- * @param sourceText - Source text of file being linted
  */
 export let setupContextForFile: (
   context: Context,
   ruleIndex: number,
   filePath: string,
-  sourceText: string,
 ) => void;
 
 /**
@@ -68,10 +67,6 @@ export interface InternalContext {
   ruleIndex: number;
   // Absolute path of file being linted
   filePath: string;
-  // `SourceCode` class instance for this rule.
-  // Rule has single `SourceCode` instance that is updated for each file
-  // (NOT new `SourceCode` instance for each file).
-  sourceCode: SourceCode;
   // Options
   options: unknown[];
   // `true` if rule can provide fixes (`meta.fixable` in `RuleMeta` is 'code' or 'whitespace')
@@ -96,7 +91,6 @@ export class Context {
     this.#internal = {
       id: fullRuleName,
       filePath: '',
-      sourceCode: new SourceCode(),
       ruleIndex: -1,
       options: [],
       isFixable,
@@ -125,8 +119,9 @@ export class Context {
   }
 
   // Getter for `SourceCode` for file being linted.
-  get sourceCode() {
-    return getInternal(this, 'access `context.sourceCode`').sourceCode;
+  get sourceCode(): SourceCode {
+    getInternal(this, 'access `context.sourceCode`');
+    return SOURCE_CODE;
   }
 
   /**
@@ -148,12 +143,11 @@ export class Context {
   }
 
   static {
-    setupContextForFile = (context, ruleIndex, filePath, sourceText) => {
+    setupContextForFile = (context, ruleIndex, filePath) => {
       // TODO: Support `options`
       const internal = context.#internal;
       internal.ruleIndex = ruleIndex;
       internal.filePath = filePath;
-      internal.sourceCode.text = sourceText;
     };
 
     getInternal = (context, actionDescription) => {

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

@@ -6,6 +6,7 @@ import {
 } from '../generated/constants.js';
 import { diagnostics, setupContextForFile } from './context.js';
 import { registeredRules } from './load.js';
+import { resetSource, setupSourceForFile } from './source_code.js';
 import { assertIs, getErrorMessage } from './utils.js';
 import { addVisitorToCompiled, compiledVisitor, finalizeCompiledVisitor, initCompiledVisitor } from './visitor.js';
 
@@ -111,14 +112,17 @@ function lintFileImpl(filePath: string, bufferId: number, buffer: Uint8Array | n
 
   const sourceText = textDecoder.decode(buffer.subarray(0, sourceByteLen));
 
+  const hasBOM = false; // TODO: Set this correctly
+  setupSourceForFile(sourceText, hasBOM);
+
   // Get visitors for this file from all rules
   initCompiledVisitor();
 
   for (let i = 0; i < ruleIds.length; i++) {
     const ruleId = ruleIds[i],
       ruleAndContext = registeredRules[ruleId];
     const { rule, context } = ruleAndContext;
-    setupContextForFile(context, i, filePath, sourceText);
+    setupContextForFile(context, i, filePath);
 
     let { visitor } = ruleAndContext;
     if (visitor === null) {
@@ -175,4 +179,7 @@ function lintFileImpl(filePath: string, bufferId: number, buffer: Uint8Array | n
     // Reset array, ready for next file
     afterHooks.length = 0;
   }
+
+  // Reset source, to free memory
+  resetSource();
 }