feat: add acf file parser

lib/common/acf_parser.dart

@@ -0,0 +1,73 @@
+import 'package:petitparser/definition.dart';
+import 'package:petitparser/parser.dart';
+
+/// Based on official JSON implementation: https://github.com/petitparser/dart-petitparser-examples
+
+/// Internal ACF parser.
+final _acfParser = AcfDefinition().build();
+
+/// Converts the given ACF-string [input] to its corresponding object.
+ACF parseAcf(String input) => _acfParser.parse(input).value;
+
+/// Type definition for ACF data.
+typedef ACF = Object? /* Map<String, ACF>|String */;
+
+/// ACF grammar definition.
+class AcfDefinition extends GrammarDefinition<ACF> {
+  @override
+  Parser<ACF> start() => ref0(entry).map((entry) => {entry.key: entry.value});
+  Parser<ACF> value() => [
+        ref0(object),
+        ref0(stringToken),
+        failure('value expected'),
+      ].toChoiceParser();
+
+  Parser<MapEntry<String, ACF>> entry() => seq3(
+        ref0(stringToken).trim(),
+        whitespace().optional(),
+        ref0(value),
+      ).map3((key, _, value) => MapEntry(key, value));
+
+  Parser<Map<String, ACF>> object() => seq5(
+        char('{'),
+        whitespace().plus(),
+        ref0(objectElements),
+        whitespace().plus(),
+        char('}'),
+      ).map5((_, __, elements, ___, ____) => elements);
+  Parser<Map<String, ACF>> objectElements() => ref0(entry)
+      .starSeparated(whitespace())
+      .map((list) => Map.fromEntries(list.elements));
+
+  Parser<String> stringToken() => seq3(
+        char('"'),
+        ref0(characterPrimitive).star(),
+        char('"'),
+      ).map3((_, chars, __) => chars.join());
+  Parser<String> characterPrimitive() => [
+        ref0(characterNormal),
+        ref0(characterEscape),
+        ref0(characterUnicode),
+      ].toChoiceParser();
+  Parser<String> characterNormal() => pattern(r'^"\');
+  Parser<String> characterEscape() => seq2(
+        char(r'\'),
+        anyOf(jsonEscapeChars.keys.join()),
+      ).map2((_, char) => jsonEscapeChars[char]!);
+  Parser<String> characterUnicode() => seq2(
+        string(r'\u'),
+        pattern('0-9A-Fa-f').timesString(4, '4-digit hex number expected'),
+      ).map2((_, value) => String.fromCharCode(int.parse(value, radix: 16)));
+}
+
+/// Escape characters of JSON strings.
+const Map<String, String> jsonEscapeChars = {
+  r'\': r'\',
+  '/': '/',
+  '"': '"',
+  'b': '\b',
+  'f': '\f',
+  'n': '\n',
+  'r': '\r',
+  't': '\t',
+};

lib/common/acf_parser_test.dart

@@ -0,0 +1,73 @@
+import 'package:petitparser/debug.dart';
+
+import 'acf_parser.dart';
+
+const input = r'''
+"AppState"
+{
+	"appid"		"250900"
+	"universe"		"1"
+	"LauncherPath"		"C:\\Program Files (x86)\\Steam\\steam.exe"
+	"name"		"The Binding of Isaac: Rebirth"
+	"StateFlags"		"4"
+	"installdir"		"The Binding of Isaac Rebirth"
+	"lastupdated"		"1702484397"
+	"SizeOnDisk"		"1163117782"
+	"StagingSize"		"0"
+	"buildid"		"10102354"
+	"LastOwner"		"76561198424783854"
+	"UpdateResult"		"0"
+	"BytesToDownload"		"0"
+	"BytesDownloaded"		"0"
+	"BytesToStage"		"0"
+	"BytesStaged"		"0"
+	"TargetBuildID"		"0"
+	"AutoUpdateBehavior"		"0"
+	"AllowOtherDownloadsWhileRunning"		"0"
+	"ScheduledAutoUpdate"		"0"
+	"InstalledDepots"
+	{
+		"250902"
+		{
+			"manifest"		"4994611894646808503"
+			"size"		"326498528"
+		}
+		"250905"
+		{
+			"manifest"		"1709017229885880564"
+			"size"		"165283102"
+			"dlcappid"		"401920"
+		}
+		"250908"
+		{
+			"manifest"		"7333987924869605149"
+			"size"		"147989670"
+			"dlcappid"		"570660"
+		}
+		"250911"
+		{
+			"manifest"		"7652847940910762229"
+			"size"		"655313480"
+			"dlcappid"		"1426300"
+		}
+	}
+	"SharedDepots"
+	{
+		"228986"		"228980"
+	}
+	"UserConfig"
+	{
+		"language"		"english"
+	}
+	"MountedConfig"
+	{
+		"language"		"english"
+	}
+}
+''';
+
+void main() {
+  final parser = AcfDefinition().build();
+  trace(parser).parse(input);
+  print(parser.parse(input).value);
+}

pubspec.yaml

@@ -101,6 +101,7 @@ dependencies:
   package_info_plus: ^5.0.1
   device_info_plus: ^9.1.1
   path: ^1.8.3
+  petitparser: ^6.0.2
 
   # others
   json_annotation: ^4.8.1