From 9de1e8feabf6be007550e2dc8932a9200bd8755c Mon Sep 17 00:00:00 2001
From: "Fred K. Schott" <fkschott@gmail.com>
Date: Mon, 22 Mar 2021 00:40:29 -0700
Subject: [PATCH] cleanup new parser handling

---
 src/compiler/parse/acorn.ts           | 25 +++++++++----------------
 src/compiler/parse/read/expression.ts | 11 +++++------
 2 files changed, 14 insertions(+), 22 deletions(-)

diff --git a/src/compiler/parse/acorn.ts b/src/compiler/parse/acorn.ts
index b884541513..c70756d79a 100644
--- a/src/compiler/parse/acorn.ts
+++ b/src/compiler/parse/acorn.ts
@@ -14,32 +14,25 @@ export const parse = (source: string): Node => {
   // });
 };
 
-export const parse_expression_at = (source: string, index: number) => {
+export const parse_expression_at = (source: string, index: number): number => {
   // TODO: Clean up after acorn -> @babel/parser move
   try {
+    // First, try to parse the expression. Unlike acorn, @babel/parser isn't relaxed
+    // enough to just stop after the first expression, so we almost always expect a
+    // parser error here instead. This is expected, so handle it.
     parseExpression(source.slice(index), {
       sourceType: 'module',
       plugins: ['jsx', 'typescript'],
     });
     throw new Error('Parse error.'); // Expected to fail.
   } catch (err) {
-    if (!err.pos) {
-      throw err;
+    if (err.message.startsWith('Unexpected token') && source[index + err.pos] === '}') {
+      return index + err.pos;
     }
-    try {
-      const result = parseExpression(source.slice(index, index + err.pos), {
-        sourceType: 'module',
-        plugins: ['jsx', 'typescript'],
-      });
-      result.start = index;
-      result.end = index + err.pos;
-      return result;
-    } catch (err2) {
-      if (err2.pos) {
-        err2.pos = index + err2.pos;
-      }
-      throw err2;
+    if (err.pos) {
+      err.pos = index + err.pos;
     }
+    throw err;
   }
 };
 // acornJsx.parseExpressionAt(source, index, {
diff --git a/src/compiler/parse/read/expression.ts b/src/compiler/parse/read/expression.ts
index 827a297216..1fe5f05f12 100644
--- a/src/compiler/parse/read/expression.ts
+++ b/src/compiler/parse/read/expression.ts
@@ -1,20 +1,19 @@
-// @ts-nocheck
-
 import { parse_expression_at } from '../acorn.js';
 import { Parser } from '../index.js';
 import { whitespace } from '../../utils/patterns.js';
 // import { Node } from 'estree';
 
+// @ts-ignore
 export default function read_expression(parser: Parser): string {
   try {
-    const node = parse_expression_at(parser.template, parser.index);
+    const start = parser.index;
+    let index = parse_expression_at(parser.template, parser.index);
     let num_parens = 0;
 
-    for (let i = parser.index; i < node.start; i += 1) {
+    for (let i = parser.index; i < start; i += 1) {
       if (parser.template[i] === '(') num_parens += 1;
     }
 
-    let index = node.end;
     while (num_parens > 0) {
       const char = parser.template[index];
 
@@ -35,7 +34,7 @@ export default function read_expression(parser: Parser): string {
 
     parser.index = index;
 
-    return parser.template.substring(node.start, node.end);
+    return parser.template.substring(start, index);
     // return node as Node;
   } catch (err) {
     parser.acorn_error(err);