perf: improve script parsing

.changeset/bright-moons-push.md

@@ -0,0 +1,5 @@
+---
+"@marko/language-tools": patch
+---
+
+Improve script parsing performance.

packages/language-tools/src/extractors/script/index.ts

@@ -119,7 +119,7 @@ class ScriptExtractor {
     this.#ts = opts.ts;
     this.#runtimeTypes = opts.runtimeTypesCode;
     this.#extractor = new Extractor(parsed);
-    this.#scriptParser = new ScriptParser(parsed.filename, parsed.code);
+    this.#scriptParser = new ScriptParser(parsed);
     this.#read = parsed.read.bind(parsed);
     this.#mutationOffsets = crawlProgramScope(this.#parsed, this.#scriptParser);
     this.#writeProgram(parsed.program);

packages/language-tools/src/extractors/script/util/script-parser.ts

@@ -5,50 +5,58 @@ import {
 } from "@babel/parser";
 import type * as t from "@babel/types";
 
+import type { Parsed } from "../../../parser";
+
 const plugins: ParserOptions["plugins"] = [
   "exportDefaultFrom",
   "importAssertions",
   "typescript",
 ];
 
 export class ScriptParser {
-  #sourceFileName: string;
-  #whitespace: string;
-  constructor(sourceFileName: string, code: string) {
-    this.#sourceFileName = sourceFileName;
-    this.#whitespace = code.replace(/[^\s]/g, " "); // used to ensure that babel provides the correct source locations.
+  #parsed: Parsed;
+  constructor(parsed: Parsed) {
+    this.#parsed = parsed;
   }
 
-  statementAt<T = t.Statement[]>(offset: number, src: string) {
+  statementAt<T = t.Statement[]>(startIndex: number, src: string) {
+    const pos = this.#parsed.positionAt(startIndex);
     try {
-      return parseStatement(this.#whitespace.slice(0, offset) + src, {
+      return parseStatement(src, {
         plugins,
+        startIndex,
+        startLine: pos.line + 1,
+        startColumn: pos.character,
         strictMode: true,
         errorRecovery: true,
         sourceType: "module",
         allowUndeclaredExports: true,
         allowSuperOutsideMethod: true,
         allowAwaitOutsideFunction: true,
         allowReturnOutsideFunction: true,
-        sourceFilename: this.#sourceFileName,
+        sourceFilename: this.#parsed.filename,
       }).program.body as unknown as T extends unknown[] ? T : Readonly<[T]>;
     } catch {
       return [];
     }
   }
 
-  expressionAt<T = t.Expression>(offset: number, src: string) {
+  expressionAt<T = t.Expression>(startIndex: number, src: string) {
+    const pos = this.#parsed.positionAt(startIndex);
     try {
-      return parseExpression(this.#whitespace.slice(0, offset) + src, {
+      return parseExpression(src, {
         plugins,
+        startIndex,
+        startLine: pos.line + 1,
+        startColumn: pos.character,
         strictMode: true,
         errorRecovery: true,
         sourceType: "module",
         allowUndeclaredExports: true,
         allowSuperOutsideMethod: true,
         allowAwaitOutsideFunction: true,
         allowReturnOutsideFunction: true,
-        sourceFilename: this.#sourceFileName,
+        sourceFilename: this.#parsed.filename,
       }) as unknown as T;
     } catch {
       return;