Replace copied grammar with direct cashc compilation for diagnostics

package.json

@@ -75,7 +75,7 @@
     ]
   },
   "dependencies": {
-    "antlr4": "^4.13.2",
+    "cashc": "file:../cashscript/packages/cashc",
     "vsce": "^2.15.0",
     "vscode-languageclient": "^7.0.0",
     "vscode-languageserver": "^7.0.0",

src/CashscriptLinter/CashscriptLinter.ts

@@ -1,25 +1,61 @@
-import { CharStream, CommonTokenStream } from 'antlr4';
-import { Diagnostic } from 'vscode-languageserver';
-import { SafeErrorListener, SafeErrorStrategy } from './ErrorListeners';
-import CashScriptLexer from './grammar/CashScriptLexer';
-import CashScriptParser from './grammar/CashScriptParser';
+import { Diagnostic, DiagnosticSeverity, Range } from 'vscode-languageserver';
+import { SafeErrorListener } from './ErrorListeners';
+import type { CashScriptError, Point } from 'cashc';
 
+type CashcModule = Pick<typeof import('cashc'), 'compileString'>;
+type SourcePoint = Pick<Point, 'line' | 'column'>;
+
+// Preserve import() in CommonJS output so VS Code can load cashc's ESM package.
+// Note that VS Code extensions *do* support ESM (since April 2025 / v1.100),
+// but Cursor does not support this yet, and we do want to support Cursor.
+const importCashc = new Function('return import("cashc")') as () => Promise<CashcModule>;
+let cashcModule: Promise<CashcModule>;
+
+async function loadCashc(): Promise<CashcModule> {
+  cashcModule ??= importCashc();
+  return cashcModule;
+}
 export default class CashscriptLinter {
-  static getDiagnostics(code: string): Diagnostic[] {
-    const errListener = new SafeErrorListener();
-
-    const inputStream = new CharStream(code);
-    const lexer = new CashScriptLexer(inputStream);
-    lexer.removeErrorListeners();
-    lexer.addErrorListener(errListener);
-
-    const tokenStream = new CommonTokenStream(lexer);
-    const parser = new CashScriptParser(tokenStream);
-    parser._errHandler = new SafeErrorStrategy();
-    parser.removeErrorListeners();
-    parser.addErrorListener(errListener);
-    const parseTree = parser.sourceFile();
-
-    return errListener.getErrs();
+  static async getDiagnostics(code: string): Promise<Diagnostic[]> {
+    const errorListener = new SafeErrorListener();
+
+    try {
+      const { compileString } = await loadCashc();
+      compileString(code, { errorListener });
+    } catch (error) {
+      if (errorListener.getErrs().length === 0) {
+        return [diagnosticFromCompilerError(error)];
+      }
+    }
+
+    return errorListener.getErrs();
   }
 }
+
+function diagnosticFromCompilerError(error: unknown): Diagnostic {
+  const originalMessage = error instanceof Error ? error.message : String(error);
+  const message = withoutLocationSuffix(originalMessage);
+  const location = (error as Partial<CashScriptError> | null | undefined)?.node?.location;
+  const messageLocation = originalMessage.match(/\bat Line (\d+), Column (\d+)$/);
+  const fallbackPoint = messageLocation
+    ? { line: Number(messageLocation[1]), column: Number(messageLocation[2]) }
+    : { line: 1, column: 0 };
+
+  const range: Range = {
+    start: pointToPosition(location?.start ?? fallbackPoint),
+    end: pointToPosition(location?.end ?? fallbackPoint),
+  };
+
+  return Diagnostic.create(range, message, DiagnosticSeverity.Error);
+}
+
+function pointToPosition(point: SourcePoint): Range['start'] {
+  return {
+    line: Math.max(point.line - 1, 0),
+    character: Math.max(point.column, 0),
+  };
+}
+
+function withoutLocationSuffix(message: string): string {
+  return message.replace(/\s+at Line \d+, Column \d+$/, '');
+}

src/CashscriptLinter/ErrorListeners.ts

@@ -1,26 +1,22 @@
-import { ErrorListener, DefaultErrorStrategy, Parser, RecognitionException, Recognizer } from 'antlr4';
 import { Diagnostic, DiagnosticSeverity, Range } from 'vscode-languageserver';
 
-export class SafeErrorListener extends ErrorListener<any> {
-  static readonly INSTANCE = new SafeErrorListener();
-
-  errs: Diagnostic[] = [];
+export class SafeErrorListener {
+  private errs: Diagnostic[] = [];
 
   getErrs(): Diagnostic[] {
     return this.errs;
   }
 
   syntaxError<T>(
-    recognizer: Recognizer<T>,
-    offendingSymbol: T,
+    _recognizer: unknown,
+    _offendingSymbol: T,
     line: number,
     charPositionInLine: number,
     message: string,
-    e?: RecognitionException,
+    _e?: unknown,
   ): void {
     const capitalisedMessage = message.charAt(0).toUpperCase() + message.slice(1);
 
-    //console.log(capitalisedMessage);
     const range: Range = {
       start: {
         line: line - 1,
@@ -36,9 +32,3 @@ export class SafeErrorListener extends ErrorListener<any> {
     this.errs.push(diag);
   }
 }
-
-export class SafeErrorStrategy extends DefaultErrorStrategy {
-  sync(recognizer: Parser): void {
-    return;
-  }
-}