[gen_l10n] Separate out AppLocalizations classes and subclasses by language code (#52335)

dev/benchmarks/test_apps/stocks/lib/i18n/stock_strings.dart

@@ -10,6 +10,9 @@ import 'package:flutter_localizations/flutter_localizations.dart';
 // ignore: unused_import
 import 'package:intl/intl.dart' as intl;
 
+import 'stock_strings_en.dart';
+import 'stock_strings_es.dart';
+
 // ignore_for_file: unnecessary_brace_in_string_interps
 
 /// Callers can lookup localized strings with an instance of StockStrings returned
@@ -65,10 +68,10 @@ import 'package:intl/intl.dart' as intl;
 /// be consistent with the languages listed in the StockStrings.supportedLocales
 /// property.
 abstract class StockStrings {
-  StockStrings(String locale) : assert(locale != null), _localeName = intl.Intl.canonicalizedLocale(locale.toString());
+  StockStrings(String locale) : assert(locale != null), localeName = intl.Intl.canonicalizedLocale(locale.toString());
 
   // ignore: unused_field
-  final String _localeName;
+  final String localeName;
 
   static StockStrings of(BuildContext context) {
     return Localizations.of<StockStrings>(context, StockStrings);
@@ -125,48 +128,6 @@ class _StockStringsDelegate extends LocalizationsDelegate<StockStrings> {
   bool shouldReload(_StockStringsDelegate old) => false;
 }
 
-/// The translations for English (`en`).
-class StockStringsEn extends StockStrings {
-  StockStringsEn([String locale = 'en']) : super(locale);
-
-  @override
-  String get title => 'Stocks';
-
-  @override
-  String get market => 'MARKET';
-
-  @override
-  String get portfolio => 'PORTFOLIO';
-}
-
-/// The translations for English, as used in the United States (`en_US`).
-class StockStringsEnUs extends StockStringsEn {
-  StockStringsEnUs([String locale = 'en_US']) : super(locale);
-
-  @override
-  String get title => 'Stocks';
-
-  @override
-  String get market => 'MARKET';
-
-  @override
-  String get portfolio => 'PORTFOLIO';
-}
-
-/// The translations for Spanish Castilian (`es`).
-class StockStringsEs extends StockStrings {
-  StockStringsEs([String locale = 'es']) : super(locale);
-
-  @override
-  String get title => 'Acciones';
-
-  @override
-  String get market => 'MERCADO';
-
-  @override
-  String get portfolio => 'CARTERA';
-}
-
 StockStrings _lookupStockStrings(Locale locale) {
   switch(locale.languageCode) {
     case 'en': {

dev/benchmarks/test_apps/stocks/lib/i18n/stock_strings_en.dart

+// Copyright 2014 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// ignore: unused_import
+import 'package:intl/intl.dart' as intl;
+import 'stock_strings.dart';
+
+// ignore_for_file: unnecessary_brace_in_string_interps
+
+/// The translations for English (`en`).
+class StockStringsEn extends StockStrings {
+  StockStringsEn([String locale = 'en']) : super(locale);
+
+  @override
+  String get title => 'Stocks';
+
+  @override
+  String get market => 'MARKET';
+
+  @override
+  String get portfolio => 'PORTFOLIO';
+}
+
+/// The translations for English, as used in the United States (`en_US`).
+class StockStringsEnUs extends StockStringsEn {
+  StockStringsEnUs(): super('en_US');
+
+  @override
+  String get title => 'Stocks';
+
+  @override
+  String get market => 'MARKET';
+
+  @override
+  String get portfolio => 'PORTFOLIO';
+}

dev/benchmarks/test_apps/stocks/lib/i18n/stock_strings_es.dart

+// Copyright 2014 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// ignore: unused_import
+import 'package:intl/intl.dart' as intl;
+import 'stock_strings.dart';
+
+// ignore_for_file: unnecessary_brace_in_string_interps
+
+/// The translations for Spanish Castilian (`es`).
+class StockStringsEs extends StockStrings {
+  StockStringsEs([String locale = 'es']) : super(locale);
+
+  @override
+  String get title => 'Acciones';
+
+  @override
+  String get market => 'MERCADO';
+
+  @override
+  String get portfolio => 'CARTERA';
+}

dev/tools/localization/gen_l10n.dart

@@ -164,11 +164,7 @@ String generateMethod(Message message, AppResourceBundle bundle) {
       }
     }
 
-    // Escape single and double quotes.
-    messageValue = messageValue.replaceAll("'", '\\\'');
-    messageValue = messageValue.replaceAll('"', '\\\"');
-
-    return "'$messageValue'";
+    return generateString(messageValue, escapeDollar: false);
   }
 
   if (message.isPlural) {
@@ -197,21 +193,43 @@ String generateMethod(Message message, AppResourceBundle bundle) {
     .replaceAll('@(message)', generateMessage());
 }
 
-String generateClass(String className, AppResourceBundle bundle, Iterable<Message> messages) {
+String generateBaseClassFile(
+  String className,
+  String fileName,
+  String header,
+  AppResourceBundle bundle,
+  Iterable<Message> messages,
+) {
   final LocaleInfo locale = bundle.locale;
+  final Iterable<String> methods = messages
+    .where((Message message) => bundle.translationFor(message) != null)
+    .map((Message message) => generateMethod(message, bundle));
 
-  String baseClassName = className;
-  if (locale.countryCode != null) {
-    baseClassName = '$className${LocaleInfo.fromString(locale.languageCode).camelCase()}';
-  }
+  return classFileTemplate
+    .replaceAll('@(header)', header)
+    .replaceAll('@(language)', describeLocale(locale.toString()))
+    .replaceAll('@(baseClass)', className)
+    .replaceAll('@(fileName)', fileName)
+    .replaceAll('@(class)', '$className${locale.camelCase()}')
+    .replaceAll('@(localeName)', locale.toString())
+    .replaceAll('@(methods)', methods.join('\n\n'));
+}
+
+String generateSubclass({
+  String className,
+  AppResourceBundle bundle,
+  Iterable<Message> messages,
+}) {
+  final LocaleInfo locale = bundle.locale;
+  final String baseClassName = '$className${LocaleInfo.fromString(locale.languageCode).camelCase()}';
 
   final Iterable<String> methods = messages
     .where((Message message) => bundle.translationFor(message) != null)
     .map((Message message) => generateMethod(message, bundle));
 
-  return classTemplate
+  return subclassTemplate
     .replaceAll('@(language)', describeLocale(locale.toString()))
-    .replaceAll('@(baseClass)', baseClassName)
+    .replaceAll('@(baseLanguageClassName)', baseClassName)
     .replaceAll('@(class)', '$className${locale.camelCase()}')
     .replaceAll('@(localeName)', locale.toString())
     .replaceAll('@(methods)', methods.join('\n\n'));
@@ -525,8 +543,25 @@ class LocalizationsGenerator {
     supportedLocales.addAll(allLocales);
   }
 
-  // Generate the AppLocalizations class, its LocalizationsDelegate subclass.
+  // Generate the AppLocalizations class, its LocalizationsDelegate subclass,
+  // and all AppLocalizations subclasses for every locale.
   String generateCode() {
+    bool isBaseClassLocale(LocaleInfo locale, String language) {
+      return locale.languageCode == language
+          && locale.countryCode == null
+          && locale.scriptCode == null;
+    }
+
+    List<LocaleInfo> getLocalesForLanguage(String language) {
+      return _allBundles.bundles
+        // Return locales for the language specified, except for the base locale itself
+        .where((AppResourceBundle bundle) {
+          final LocaleInfo locale = bundle.locale;
+          return !isBaseClassLocale(locale, language) && locale.languageCode == language;
+        })
+        .map((AppResourceBundle bundle) => bundle.locale).toList();
+    }
+
     final String directory = path.basename(l10nDirectory.path);
     final String outputFileName = path.basename(outputFile.path);
 
@@ -540,15 +575,49 @@ class LocalizationsGenerator {
       _allBundles.locales.map<String>((LocaleInfo locale) => '\'${locale.languageCode}\'')
     );
 
-    final StringBuffer allMessagesClasses = StringBuffer();
     final List<LocaleInfo> allLocales = _allBundles.locales.toList()..sort();
+    final String fileName = outputFileName.split('.')[0];
     for (final LocaleInfo locale in allLocales) {
-      allMessagesClasses.writeln();
-      allMessagesClasses.writeln(
-        generateClass(className, _allBundles.bundleFor(locale), _allMessages)
-      );
+      if (isBaseClassLocale(locale, locale.languageCode)) {
+        final File localeMessageFile = _fs.file(
+          path.join(l10nDirectory.path, '${fileName}_$locale.dart'),
+        );
+
+        // Generate the template for the base class file. Further string
+        // interpolation will be done to determine if there are
+        // subclasses that extend the base class.
+        final String languageBaseClassFile = generateBaseClassFile(
+          className,
+          outputFileName,
+          header,
+          _allBundles.bundleFor(locale),
+          _allMessages,
+        );
+
+        // Every locale for the language except the base class.
+        final List<LocaleInfo> localesForLanguage = getLocalesForLanguage(locale.languageCode);
+
+        // Generate every subclass that is needed for the particular language
+        final Iterable<String> subclasses = localesForLanguage.map<String>((LocaleInfo locale) {
+          return generateSubclass(
+            className: className,
+            bundle: _allBundles.bundleFor(locale),
+            messages: _allMessages,
+          );
+        });
+
+        localeMessageFile.writeAsStringSync(
+          languageBaseClassFile.replaceAll('@(subclasses)', subclasses.join()),
+        );
+      }
     }
 
+    final Iterable<String> localeImports = supportedLocales
+      .where((LocaleInfo locale) => isBaseClassLocale(locale, locale.languageCode))
+      .map((LocaleInfo locale) {
+        return "import '${fileName}_${locale.toString()}.dart';";
+      });
+
     final String lookupBody = generateLookupBody(_allBundles, className);
 
     return fileTemplate
@@ -558,7 +627,7 @@ class LocalizationsGenerator {
       .replaceAll('@(importFile)', '$directory/$outputFileName')
       .replaceAll('@(supportedLocales)', supportedLocalesCode.join(',\n    '))
       .replaceAll('@(supportedLanguageCodes)', supportedLanguageCodes.join(', '))
-      .replaceAll('@(allMessagesClasses)', allMessagesClasses.toString().trim())
+      .replaceAll('@(messageClassImports)', localeImports.join('\n'))
       .replaceAll('@(lookupName)', '_lookup$className')
       .replaceAll('@(lookupBody)', lookupBody);
   }

dev/tools/localization/gen_l10n_templates.dart

@@ -12,6 +12,8 @@ import 'package:flutter_localizations/flutter_localizations.dart';
 // ignore: unused_import
 import 'package:intl/intl.dart' as intl;
 
+@(messageClassImports)
+
 // ignore_for_file: unnecessary_brace_in_string_interps
 
 /// Callers can lookup localized strings with an instance of @(class) returned
@@ -67,10 +69,10 @@ import 'package:intl/intl.dart' as intl;
 /// be consistent with the languages listed in the @(class).supportedLocales
 /// property.
 abstract class @(class) {
-  @(class)(String locale) : assert(locale != null), _localeName = intl.Intl.canonicalizedLocale(locale.toString());
+  @(class)(String locale) : assert(locale != null), localeName = intl.Intl.canonicalizedLocale(locale.toString());
 
   // ignore: unused_field
-  final String _localeName;
+  final String localeName;
 
   static @(class) of(BuildContext context) {
     return Localizations.of<@(class)>(context, @(class));
@@ -117,8 +119,6 @@ class _@(class)Delegate extends LocalizationsDelegate<@(class)> {
   bool shouldReload(_@(class)Delegate old) => false;
 }
 
-@(allMessagesClasses)
-
 @(class) @(lookupName)(Locale locale) {
   switch(locale.languageCode) {
     @(lookupBody)
@@ -130,14 +130,14 @@ class _@(class)Delegate extends LocalizationsDelegate<@(class)> {
 
 const String numberFormatTemplate = '''
     final intl.NumberFormat @(placeholder)NumberFormat = intl.NumberFormat.@(format)(
-      locale: _localeName,
+      locale: localeName,
       @(parameters)
     );
     final String @(placeholder)String = @(placeholder)NumberFormat.format(@(placeholder));
 ''';
 
 const String dateFormatTemplate = '''
-    final intl.DateFormat @(placeholder)DateFormat = intl.DateFormat.@(format)(_localeName);
+    final intl.DateFormat @(placeholder)DateFormat = intl.DateFormat.@(format)(localeName);
     final String @(placeholder)String = @(placeholder)DateFormat.format(@(placeholder));
 ''';
 
@@ -166,18 +166,36 @@ const String pluralMethodTemplate = '''
 @(numberFormatting)
     return intl.Intl.pluralLogic(
       @(count),
-      locale: _localeName,
+      locale: localeName,
 @(pluralLogicArgs),
     );
   }''';
 
-const String classTemplate = '''
+const String classFileTemplate = '''
+@(header)
+// ignore: unused_import
+import 'package:intl/intl.dart' as intl;
+import '@(fileName)';
+
+// ignore_for_file: unnecessary_brace_in_string_interps
+
 /// The translations for @(language) (`@(localeName)`).
 class @(class) extends @(baseClass) {
   @(class)([String locale = '@(localeName)']) : super(locale);
 
 @(methods)
-}''';
+}
+@(subclasses)''';
+
+const String subclassTemplate = '''
+
+/// The translations for @(language) (`@(localeName)`).
+class @(class) extends @(baseLanguageClassName) {
+  @(class)(): super('@(localeName)');
+
+@(methods)
+}
+''';
 
 const String baseClassGetterTemplate = '''
   // @(comment)

dev/tools/localization/gen_l10n_types.dart

@@ -104,11 +104,11 @@ const Set<String> _validNumberFormats = <String>{
 //
 // Example of code that uses named parameters:
 // final NumberFormat format = NumberFormat.compact(
-//   locale: _localeName,
+//   locale: localeName,
 // );
 //
 // Example of code that uses positional parameters:
-// final NumberFormat format = NumberFormat.scientificPattern(_localeName);
+// final NumberFormat format = NumberFormat.scientificPattern(localeName);
 const Set<String> _numberFormatsWithNamedParameters = <String>{
   'compact',
   'compactCurrency',

dev/tools/localization/localizations_utils.dart

@@ -371,37 +371,62 @@ String generateClassDeclaration(
 class $classNamePrefix$camelCaseName extends $superClass {''';
 }
 
-/// Return `s` as a Dart-parseable string.
-///
-/// The result tries to avoid character escaping:
+/// Return the input string as a Dart-parseable string.
 ///
 /// ```
 /// foo => 'foo'
 /// foo "bar" => 'foo "bar"'
 /// foo 'bar' => "foo 'bar'"
 /// foo 'bar' "baz" => '''foo 'bar' "baz"'''
-/// foo\bar => r'foo\bar'
+/// foo\bar => 'foo\\bar'
+/// foo\nbar => 'foo\\\\nbar'
+/// ```
+///
+/// When [shouldEscapeDollar] is set to true, the
+/// result avoids character escaping, with the
+/// exception of the dollar sign:
+///
+/// ```
+/// foo$bar = 'foo\$bar'
 /// ```
 ///
+/// When [shouldEscapeDollar] is set to false, the
+/// result tries to avoid character escaping:
+///
+/// ```
+/// foo$bar => 'foo\\\$bar'
+/// ```
+///
+/// [shouldEscapeDollar] is true by default.
+///
 /// Strings with newlines are not supported.
-String generateString(String value) {
-  assert(!value.contains('\n'));
-  final String rawPrefix = value.contains(r'$') || value.contains(r'\') ? 'r' : '';
-  if (!value.contains("'"))
-    return "$rawPrefix'$value'";
-  if (!value.contains('"'))
-    return '$rawPrefix"$value"';
-  if (!value.contains("'''"))
-    return "$rawPrefix'''$value'''";
-  if (!value.contains('"""'))
-    return '$rawPrefix"""$value"""';
-
-  return value.split("'''")
-    .map(generateString)
-    // If value contains more than 6 consecutive single quotes some empty strings may be generated.
-    // The following map removes them.
-    .map((String part) => part == "''" ? '' : part)
-    .join(" \"'''\" ");
+String generateString(String value, { bool escapeDollar = true }) {
+  assert(escapeDollar != null);
+  assert(
+    !value.contains('\n'),
+    'Since it is assumed that the input string comes '
+    'from a json/arb file source, messages cannot '
+    'contain newlines.'
+  );
+
+  const String backslash = '__BACKSLASH__';
+  assert(
+    !value.contains(backslash),
+    'Input string cannot contain the sequence: '
+    '"__BACKSLASH__", as it is used as part of '
+    'backslash character processing.'
+  );
+  value = value.replaceAll('\\', backslash);
+
+  if (escapeDollar)
+    value = value.replaceAll('\$', '\\\$');
+
+  value = value
+    .replaceAll("'", "\\'")
+    .replaceAll('"', '\\"')
+    .replaceAll(backslash, '\\\\');
+
+  return "'$value'";
 }
 
 /// Only used to generate localization strings for the Kannada locale ('kn') because

dev/tools/test/localization/gen_l10n_test.dart

@@ -710,6 +710,39 @@ void main() {
   });
 
   group('generateCode', () {
+    test('should generate a file per language', () {
+      const String singleEnCaMessageArbFileString = '''
+{
+  "title": "Canadian Title"
+}''';
+      fs.currentDirectory.childDirectory('lib').childDirectory('l10n')..createSync(recursive: true)
+        ..childFile(defaultTemplateArbFileName).writeAsStringSync(singleMessageArbFileString)
+        ..childFile('app_en_CA.arb').writeAsStringSync(singleEnCaMessageArbFileString);
+
+      final LocalizationsGenerator generator = LocalizationsGenerator(fs);
+      try {
+        generator.initialize(
+          l10nDirectoryPath: defaultArbPathString,
+          templateArbFileName: defaultTemplateArbFileName,
+          outputFileString: defaultOutputFileString,
+          classNameString: defaultClassNameString,
+        );
+        generator.loadResources();
+        generator.writeOutputFile();
+      } on Exception catch (e) {
+        fail('Generating output files should not fail: $e');
+      }
+
+      expect(fs.isFileSync(path.join('lib', 'l10n', 'output-localization-file_en.dart')), true);
+      expect(fs.isFileSync(path.join('lib', 'l10n', 'output-localization-file_en_US.dart')), false);
+
+      final String englishLocalizationsFile = fs.file(
+        path.join('lib', 'l10n', 'output-localization-file_en.dart')
+      ).readAsStringSync();
+      expect(englishLocalizationsFile, contains('class AppLocalizationsEnCa extends AppLocalizationsEn'));
+      expect(englishLocalizationsFile, contains('class AppLocalizationsEn extends AppLocalizations'));
+    });
+
     group('DateTime tests', () {
       test('throws an exception when improperly formatted date is passed in', () {
         const String singleDateMessageArbFileString = '''
@@ -1112,37 +1145,4 @@ void main() {
       });
     });
   });
-
-  group('generateString', () {
-    test('handles simple string', () {
-      expect(generateString('abc'), "'abc'");
-    });
-    test('handles string with quote', () {
-      expect(generateString("ab'c"), '''"ab'c"''');
-    });
-    test('handles string with double quote', () {
-      expect(generateString('ab"c'), """'ab"c'""");
-    });
-    test('handles string with both single and double quote', () {
-      expect(generateString('''a'b"c'''), """'''a'b"c'''""");
-    });
-    test('handles string with a triple single quote and a double quote', () {
-      expect(generateString("""a"b'''c"""), '''"""a"b\'''c"""''');
-    });
-    test('handles string with a triple double quote and a single quote', () {
-      expect(generateString('''a'b"""c'''), """'''a'b\"""c'''""");
-    });
-    test('handles string with both triple single and triple double quote', () {
-      expect(generateString('''a\'''\'''\''b"""c'''), """'a' "'''"  "'''" '''''b\"""c'''""");
-    });
-    test('handles dollar', () {
-      expect(generateString(r'ab$c'), r"r'ab$c'");
-    });
-    test('handles back slash', () {
-      expect(generateString(r'ab\c'), r"r'ab\c'");
-    });
-    test("doesn't support multiline strings", () {
-      expect(() => generateString('ab\nc'), throwsA(isA<AssertionError>()));
-    });
-  });
 }

dev/tools/test/localization/localizations_utils_test.dart

+// Copyright 2014 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import '../../localization/localizations_utils.dart';
+
+import '../common.dart';
+
+void main() {
+  group('generateString', () {
+    test('handles simple string', () {
+      expect(generateString('abc'), "'abc'");
+    });
+
+    test('handles string with quote', () {
+      expect(generateString("ab'c"), "'ab\\\'c'");
+    });
+
+    test('handles string with double quote', () {
+      expect(generateString('ab"c'), "'ab\\\"c'");
+    });
+
+    test('handles string with both single and double quote', () {
+      expect(generateString('''a'b"c'''), '\'a\\\'b\\"c\'');
+    });
+
+    test('handles string with a triple single quote and a double quote', () {
+      expect(generateString("""a"b'''c"""), '\'a\\"b\\\'\\\'\\\'c\'');
+    });
+
+    test('handles string with a triple double quote and a single quote', () {
+      expect(generateString('''a'b"""c'''), '\'a\\\'b\\"\\"\\"c\'');
+    });
+
+    test('handles string with both triple single and triple double quote', () {
+      expect(generateString('''a\'''b"""c'''), '\'a\\\'\\\'\\\'b\\"\\"\\"c\'');
+    });
+
+    test('escapes dollar when escapeDollar is true', () {
+      expect(generateString(r'ab$c', escapeDollar: true), "'ab\\\$c'");
+    });
+
+    test('does not escape dollar when escapeDollar  is false', () {
+      expect(generateString(r'ab$c', escapeDollar: false), "'ab\$c'");
+    });
+
+    test('handles backslash', () {
+      expect(generateString(r'ab\c'), "'ab\\\\c'");
+    });
+
+    test('handles backslash followed by "n" character', () {
+      expect(generateString(r'ab\nc'), "'ab\\\\nc'");
+    });
+
+    test('does not support multiline strings', () {
+      expect(() => generateString('ab\nc'), throwsA(isA<AssertionError>()));
+    });
+  });
+}