Add generating supportedLocales array in l10n.dart

Resolves #2.

lib/src/generator/l10n_dart_generator.dart

@@ -1,11 +1,13 @@
+import 'package:arbify/src/language_identifier_parser/locale.dart';
+import 'package:arbify/src/language_identifier_parser/locale_parser.dart';
+
 import '../icu_parser/icu_parser.dart';
 import '../arb_parser/arb_file.dart';
 
 class L10nDartGenerator {
   const L10nDartGenerator();
 
   String generate(ArbFile template, List<String> locales) {
-    final localeItems = locales.map((locale) => "\n        '$locale',").join();
     final messagesBuilder = StringBuffer();
 
     template.messages.forEach((message) {
@@ -50,6 +52,13 @@ class L10nDartGenerator {
 
     final messages = messagesBuilder.toString();
 
+    final parsedLocales = locales
+        .map((locale) => LanguageIdentifierParser().parse(locale))
+        .toList();
+    final supportedLocales = _generateSupportedLocalesArray(parsedLocales);
+    final localeItems =
+        parsedLocales.map((locale) => "\n        '${locale.language}',").join();
+
     return """// File generated with arbify_flutter.
 // DO NOT MODIFY BY HAND.
 // ignore_for_file: lines_longer_than_80_chars, non_constant_identifier_names
@@ -82,6 +91,9 @@ class S {
 class ArbifyLocalizationsDelegate extends LocalizationsDelegate<S> {
   const ArbifyLocalizationsDelegate();
 
+  List<Locale> get supportedLocales => [
+$supportedLocales  ];
+
   @override
   bool isSupported(Locale locale) => [$localeItems
       ].contains(locale.languageCode);
@@ -94,4 +106,21 @@ class ArbifyLocalizationsDelegate extends LocalizationsDelegate<S> {
 }
 """;
   }
+
+  String _generateSupportedLocalesArray(List<Locale> locales) {
+    final supportedLocales = StringBuffer();
+
+    locales.forEach((locale) {
+      final languageCode = "languageCode: '${locale.language}'";
+      final scriptCode =
+          locale.script == null ? '' : ", scriptCode: '${locale.script}'";
+      final countryCode =
+          locale.region == null ? '' : ", countryCode: '${locale.region}'";
+
+      supportedLocales.writeln(
+          '        Locale.fromSubtags($languageCode$scriptCode$countryCode),');
+    });
+
+    return supportedLocales.toString();
+  }
 }

lib/src/language_identifier_parser/locale.dart

@@ -0,0 +1,7 @@
+class Locale {
+  final String language;
+  final String script;
+  final String region;
+
+  Locale({this.language, this.script, this.region});
+}

lib/src/language_identifier_parser/locale_parser.dart

@@ -0,0 +1,25 @@
+// https://www.unicode.org/reports/tr35/#Unicode_language_identifier
+import 'package:arbify/src/language_identifier_parser/locale.dart';
+import 'package:petitparser/petitparser.dart';
+
+class LanguageIdentifierParser {
+  Parser get alphanum => letter() | digit();
+  Parser get sep => char('_') | char('-');
+
+  Parser get language =>
+      (letter().repeat(2, 3) | letter().repeat(5, 8)).flatten();
+
+  Parser get script => letter().times(4).flatten();
+  Parser get region => (letter().times(2) | digit().times(3)).flatten();
+
+  Parser get scriptPart => (sep & script).map((value) => value[1]).optional();
+  Parser get regionPart => (sep & region).map((value) => value[1]).optional();
+
+  Parser get id => language & scriptPart & regionPart;
+
+  Locale parse(String text) => id
+      .map((value) =>
+          Locale(language: value[0], script: value[1], region: value[2]))
+      .parse(text)
+      .value;
+}

test/locale_parser_test.dart

@@ -0,0 +1,39 @@
+import 'package:arbify/src/language_identifier_parser/locale_parser.dart';
+import 'package:test/test.dart';
+
+void main() {
+  test('parses en-US', () {
+    final locale = LanguageIdentifierParser().parse('en-US');
+    expect(locale.language, equals('en'));
+    expect(locale.script, isNull);
+    expect(locale.region, equals('US'));
+  });
+
+  test('parses en_GB', () {
+    final locale = LanguageIdentifierParser().parse('en_GB');
+    expect(locale.language, equals('en'));
+    expect(locale.script, isNull);
+    expect(locale.region, equals('GB'));
+  });
+
+  test('parses es-419', () {
+    final locale = LanguageIdentifierParser().parse('es-419');
+    expect(locale.language, equals('es'));
+    expect(locale.script, isNull);
+    expect(locale.region, equals('419'));
+  });
+
+  test('parses uz-Cyrl', () {
+    final locale = LanguageIdentifierParser().parse('uz-Cyrl');
+    expect(locale.language, equals('uz'));
+    expect(locale.script, equals('Cyrl'));
+    expect(locale.region, isNull);
+  });
+
+  test('parses zn-Hans-TW', () {
+    final locale = LanguageIdentifierParser().parse('zn-Hans-TW');
+    expect(locale.language, equals('zn'));
+    expect(locale.script, equals('Hans'));
+    expect(locale.region, equals('TW'));
+  });
+}