From c5cbdd89438f7a11ef58086d3a1ae54e4fe15edf Mon Sep 17 00:00:00 2001
From: Lukas Renggli <renggli@gmail.com>
Date: Wed, 4 Dec 2024 18:52:12 +0100
Subject: [PATCH] Answer for
 https://github.com/petitparser/dart-petitparser/issues/184

---
 test/regression_test.dart | 33 +++++++++++++++++++++++++++++++++
 1 file changed, 33 insertions(+)

diff --git a/test/regression_test.dart b/test/regression_test.dart
index 16b80f33..327b1cee 100644
--- a/test/regression_test.dart
+++ b/test/regression_test.dart
@@ -56,6 +56,21 @@ class NestedGrammar3 {
       char('0').map((value) => "'$value' (singleCharacter)");
 }
 
+class ProtobufGrammar extends GrammarDefinition {
+  @override
+  Parser start() => ref0(file);
+  Parser file() =>
+      ref0(definition).star() & (endOfInput().trim() | ref0(definition));
+  Parser definition() => ref0(message);
+  Parser message() =>
+      string('message').trim() &
+      ref0(identifier).trim() &
+      char('{').trim() &
+      char('}').trim();
+  Parser identifier() =>
+      (letter() & word().star()).flatten('identifier expected');
+}
+
 void main() {
   test('flatten().trim()', () {
     final parser = word().plus().flatten().trim();
@@ -656,4 +671,22 @@ void main() {
       expect(parser, isParseSuccess('\u{2FFFF}', result: 0x2FFFF));
     });
   });
+  group('github.com/petitparser/dart-petitparser/issues/184', () {
+    final parser = ProtobufGrammar().build();
+    test('valid', () {
+      expect(parser.parse(' '), isSuccess());
+      expect(parser.parse('message foo {} '), isSuccess());
+      expect(parser.parse('message foo {} message bar {} '), isSuccess());
+    });
+    test('invalid', () {
+      expect(parser.parse('message '),
+          isFailure(message: 'identifier expected', position: 8));
+      expect(parser.parse('message 123'),
+          isFailure(message: 'identifier expected', position: 8));
+      expect(parser.parse('message Empty'),
+          isFailure(message: '"{" expected', position: 13));
+      expect(parser.parse('message Empty {'),
+          isFailure(message: '"}" expected', position: 15));
+    });
+  });
 }