feat: add CodeParser for barcode classification per PRD §4

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

lib/services/code_parser.dart

@@ -0,0 +1,39 @@
+// lib/services/code_parser.dart
+class CodeParser {
+  static final _zongpaiRegex = RegExp(
+    r'^\d{2}(B|C|T)\d+$|^\d{2}(BW|CW)\d{4}$',
+  );
+  static final _locationRegex = RegExp(
+    r'^[A-Z0-9]+-[A-Z0-9]+-[A-Z0-9]+$',
+  );
+  static final _transitRegex = RegExp(
+    r'^TRANS-',
+  );
+
+  static ParseResult parse(String code) {
+    if (code.isEmpty) {
+      return ParseResult(type: CodeType.invalid, value: code);
+    }
+    if (_transitRegex.hasMatch(code)) {
+      return ParseResult(type: CodeType.locationTransit, value: code);
+    }
+    if (_zongpaiRegex.hasMatch(code)) {
+      return ParseResult(type: CodeType.zongpaiNo, value: code);
+    }
+    if (_locationRegex.hasMatch(code)) {
+      return ParseResult(type: CodeType.locationNormal, value: code);
+    }
+    return ParseResult(type: CodeType.invalid, value: code);
+  }
+
+  static bool isLocation(CodeType type) =>
+      type == CodeType.locationNormal || type == CodeType.locationTransit;
+}
+
+enum CodeType { zongpaiNo, locationNormal, locationTransit, invalid }
+
+class ParseResult {
+  final CodeType type;
+  final String value;
+  ParseResult({required this.type, required this.value});
+}

test/services/code_parser_test.dart

@@ -0,0 +1,58 @@
+import 'package:flutter_test/flutter_test.dart';
+import 'package:pad_scanner/services/code_parser.dart';
+
+void main() {
+  group('CodeParser.parse', () {
+    test('identifies zongpaiNo type B', () {
+      final result = CodeParser.parse('26B1');
+      expect(result.type, CodeType.zongpaiNo);
+      expect(result.value, '26B1');
+    });
+    test('identifies zongpaiNo type C', () {
+      final result = CodeParser.parse('26C12');
+      expect(result.type, CodeType.zongpaiNo);
+    });
+    test('identifies zongpaiNo type T', () {
+      final result = CodeParser.parse('26T3');
+      expect(result.type, CodeType.zongpaiNo);
+    });
+    test('identifies zongpaiNo type BW (4 digits)', () {
+      final result = CodeParser.parse('26BW0001');
+      expect(result.type, CodeType.zongpaiNo);
+    });
+    test('identifies zongpaiNo type CW (4 digits)', () {
+      final result = CodeParser.parse('26CW0015');
+      expect(result.type, CodeType.zongpaiNo);
+    });
+    test('rejects BW with non-4-digit serial', () {
+      expect(CodeParser.parse('26BW01').type, CodeType.invalid);
+    });
+    test('rejects CW with non-4-digit serial', () {
+      expect(CodeParser.parse('26CW15').type, CodeType.invalid);
+    });
+    test('identifies normal location code', () {
+      final result = CodeParser.parse('A01-02-03');
+      expect(result.type, CodeType.locationNormal);
+      expect(result.value, 'A01-02-03');
+    });
+    test('identifies transit location code', () {
+      final result = CodeParser.parse('TRANS-01');
+      expect(result.type, CodeType.locationTransit);
+    });
+    test('rejects lowercase location code', () {
+      expect(CodeParser.parse('a01-02-03').type, CodeType.invalid);
+    });
+    test('rejects invalid code', () {
+      expect(CodeParser.parse('HELLO123').type, CodeType.invalid);
+    });
+    test('rejects empty string', () {
+      expect(CodeParser.parse('').type, CodeType.invalid);
+    });
+    test('isLocation helper', () {
+      expect(CodeParser.isLocation(CodeType.locationNormal), true);
+      expect(CodeParser.isLocation(CodeType.locationTransit), true);
+      expect(CodeParser.isLocation(CodeType.zongpaiNo), false);
+      expect(CodeParser.isLocation(CodeType.invalid), false);
+    });
+  });
+}