dev/tools/localization/localizations_utils.dart - external/github.com/flutter/flutter - Git at Google

 // 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 'dart:convert';
 import 'dart:io';

 import 'package:args/args.dart' as argslib;
 import 'package:meta/meta.dart';

 import 'language_subtag_registry.dart';

 typedef HeaderGenerator = String Function(String regenerateInstructions);
 typedef ConstructorGenerator = String Function(LocaleInfo locale);

 int sortFilesByPath (FileSystemEntity a, FileSystemEntity b) {
   return a.path.compareTo(b.path);
 }

 /// Simple data class to hold parsed locale. Does not promise validity of any data.
 @immutable
 class LocaleInfo implements Comparable<LocaleInfo> {
   const LocaleInfo({
     this.languageCode,
     this.scriptCode,
     this.countryCode,
     this.length,
     this.originalString,
   });

   /// Simple parser. Expects the locale string to be in the form of 'language_script_COUNTRY'
   /// where the language is 2 characters, script is 4 characters with the first uppercase,
   /// and country is 2-3 characters and all uppercase.
   ///
   /// 'language_COUNTRY' or 'language_script' are also valid. Missing fields will be null.
   ///
   /// When `deriveScriptCode` is true, if [scriptCode] was unspecified, it will
   /// be derived from the [languageCode] and [countryCode] if possible.
   factory LocaleInfo.fromString(String locale, { bool deriveScriptCode = false }) {
     final List<String> codes = locale.split('_'); // [language, script, country]
     assert(codes.isNotEmpty && codes.length < 4);
     final String languageCode = codes[0];
     String scriptCode;
     String countryCode;
     int length = codes.length;
     String originalString = locale;
     if (codes.length == 2) {
       scriptCode = codes[1].length >= 4 ? codes[1] : null;
       countryCode = codes[1].length < 4 ? codes[1] : null;
     } else if (codes.length == 3) {
       scriptCode = codes[1].length > codes[2].length ? codes[1] : codes[2];
       countryCode = codes[1].length < codes[2].length ? codes[1] : codes[2];
     }
     assert(codes[0] != null && codes[0].isNotEmpty);
     assert(countryCode == null || countryCode.isNotEmpty);
     assert(scriptCode == null || scriptCode.isNotEmpty);

     /// Adds scriptCodes to locales where we are able to assume it to provide
     /// finer granularity when resolving locales.
     ///
     /// The basis of the assumptions here are based off of known usage of scripts
     /// across various countries. For example, we know Taiwan uses traditional (Hant)
     /// script, so it is safe to apply (Hant) to Taiwanese languages.
     if (deriveScriptCode && scriptCode == null) {
       switch (languageCode) {
         case 'zh': {
           if (countryCode == null) {
             scriptCode = 'Hans';
           }
           switch (countryCode) {
             case 'CN':
             case 'SG':
               scriptCode = 'Hans';
               break;
             case 'TW':
             case 'HK':
             case 'MO':
               scriptCode = 'Hant';
               break;
           }
           break;
         }
         case 'sr': {
           if (countryCode == null) {
             scriptCode = 'Cyrl';
           }
           break;
         }
       }
       // Increment length if we were able to assume a scriptCode.
       if (scriptCode != null) {
         length += 1;
       }
       // Update the base string to reflect assumed scriptCodes.
       originalString = languageCode;
       if (scriptCode != null)
         originalString += '_' + scriptCode;
       if (countryCode != null)
         originalString += '_' + countryCode;
     }

     return LocaleInfo(
       languageCode: languageCode,
       scriptCode: scriptCode,
       countryCode: countryCode,
       length: length,
       originalString: originalString,
     );
   }

   final String languageCode;
   final String scriptCode;
   final String countryCode;
   final int length;             // The number of fields. Ranges from 1-3.
   final String originalString;  // Original un-parsed locale string.

   String camelCase() {
     return originalString
       .split('_')
       .map<String>((String part) => part.substring(0, 1).toUpperCase() + part.substring(1).toLowerCase())
       .join('');
   }

   @override
   bool operator ==(Object other) {
     return other is LocaleInfo
         && other.originalString == originalString;
   }

   @override
   int get hashCode {
     return originalString.hashCode;
   }

   @override
   String toString() {
     return originalString;
   }

   @override
   int compareTo(LocaleInfo other) {
     return originalString.compareTo(other.originalString);
   }
 }

 /// Parse the data for a locale from a file, and store it in the [attributes]
 /// and [resources] keys.
 void loadMatchingArbsIntoBundleMaps({
   @required Directory directory,
   @required RegExp filenamePattern,
   @required Map<LocaleInfo, Map<String, String>> localeToResources,
   @required Map<LocaleInfo, Map<String, dynamic>> localeToResourceAttributes,
 }) {
   assert(directory != null);
   assert(filenamePattern != null);
   assert(localeToResources != null);
   assert(localeToResourceAttributes != null);

   /// Set that holds the locales that were assumed from the existing locales.
   ///
   /// For example, when the data lacks data for zh_Hant, we will use the data of
   /// the first Hant Chinese locale as a default by repeating the data. If an
   /// explicit match is later found, we can reference this set to see if we should
   /// overwrite the existing assumed data.
   final Set<LocaleInfo> assumedLocales = <LocaleInfo>{};

   for (final FileSystemEntity entity in directory.listSync().toList()..sort(sortFilesByPath)) {
     final String entityPath = entity.path;
     if (FileSystemEntity.isFileSync(entityPath) && filenamePattern.hasMatch(entityPath)) {
       final String localeString = filenamePattern.firstMatch(entityPath)[1];
       final File arbFile = File(entityPath);

       // Helper method to fill the maps with the correct data from file.
       void populateResources(LocaleInfo locale, File file) {
         final Map<String, String> resources = localeToResources[locale];
         final Map<String, dynamic> attributes = localeToResourceAttributes[locale];
         final Map<String, dynamic> bundle = json.decode(file.readAsStringSync()) as Map<String, dynamic>;
         for (final String key in bundle.keys) {
           // The ARB file resource "attributes" for foo are called @foo.
           if (key.startsWith('@'))
             attributes[key.substring(1)] = bundle[key];
           else
             resources[key] = bundle[key] as String;
         }
       }
       // Only pre-assume scriptCode if there is a country or script code to assume off of.
       // When we assume scriptCode based on languageCode-only, we want this initial pass
       // to use the un-assumed version as a base class.
       LocaleInfo locale = LocaleInfo.fromString(localeString, deriveScriptCode: localeString.split('_').length > 1);
       // Allow overwrite if the existing data is assumed.
       if (assumedLocales.contains(locale)) {
         localeToResources[locale] = <String, String>{};
         localeToResourceAttributes[locale] = <String, dynamic>{};
         assumedLocales.remove(locale);
       } else {
         localeToResources[locale] ??= <String, String>{};
         localeToResourceAttributes[locale] ??= <String, dynamic>{};
       }
       populateResources(locale, arbFile);
       // Add an assumed locale to default to when there is no info on scriptOnly locales.
       locale = LocaleInfo.fromString(localeString, deriveScriptCode: true);
       if (locale.scriptCode != null) {
         final LocaleInfo scriptLocale = LocaleInfo.fromString(locale.languageCode + '_' + locale.scriptCode);
         if (!localeToResources.containsKey(scriptLocale)) {
           assumedLocales.add(scriptLocale);
           localeToResources[scriptLocale] ??= <String, String>{};
           localeToResourceAttributes[scriptLocale] ??= <String, dynamic>{};
           populateResources(scriptLocale, arbFile);
         }
       }
     }
   }
 }

 void exitWithError(String errorMessage) {
   assert(errorMessage != null);
   stderr.writeln('fatal: $errorMessage');
   exit(1);
 }

 void checkCwdIsRepoRoot(String commandName) {
   final bool isRepoRoot = Directory('.git').existsSync();

   if (!isRepoRoot) {
     exitWithError(
       '$commandName must be run from the root of the Flutter repository. The '
       'current working directory is: ${Directory.current.path}'
     );
   }
 }

 GeneratorOptions parseArgs(List<String> rawArgs) {
   final argslib.ArgParser argParser = argslib.ArgParser()
     ..addFlag(
       'overwrite',
       abbr: 'w',
       defaultsTo: false,
     )
     ..addFlag(
       'material',
       help: 'Whether to print the generated classes for the Material package only. Ignored when --overwrite is passed.',
       defaultsTo: false,
     )
     ..addFlag(
       'cupertino',
       help: 'Whether to print the generated classes for the Cupertino package only. Ignored when --overwrite is passed.',
       defaultsTo: false,
     );
   final argslib.ArgResults args = argParser.parse(rawArgs);
   final bool writeToFile = args['overwrite'] as bool;
   final bool materialOnly = args['material'] as bool;
   final bool cupertinoOnly = args['cupertino'] as bool;

   return GeneratorOptions(writeToFile: writeToFile, materialOnly: materialOnly, cupertinoOnly: cupertinoOnly);
 }

 class GeneratorOptions {
   GeneratorOptions({
     @required this.writeToFile,
     @required this.materialOnly,
     @required this.cupertinoOnly,
   });

   final bool writeToFile;
   final bool materialOnly;
   final bool cupertinoOnly;
 }

 // See also //master/tools/gen_locale.dart in the engine repo.
 Map<String, List<String>> _parseSection(String section) {
   final Map<String, List<String>> result = <String, List<String>>{};
   List<String> lastHeading;
   for (final String line in section.split('\n')) {
     if (line == '')
       continue;
     if (line.startsWith('  ')) {
       lastHeading[lastHeading.length - 1] = '${lastHeading.last}${line.substring(1)}';
       continue;
     }
     final int colon = line.indexOf(':');
     if (colon <= 0)
       throw 'not sure how to deal with "$line"';
     final String name = line.substring(0, colon);
     final String value = line.substring(colon + 2);
     lastHeading = result.putIfAbsent(name, () => <String>[]);
     result[name].add(value);
   }
   return result;
 }

 final Map<String, String> _languages = <String, String>{};
 final Map<String, String> _regions = <String, String>{};
 final Map<String, String> _scripts = <String, String>{};
 const String kProvincePrefix = ', Province of ';
 const String kParentheticalPrefix = ' (';

 /// Prepares the data for the [describeLocale] method below.
 ///
 /// The data is obtained from the official IANA registry.
 void precacheLanguageAndRegionTags() {
   final List<Map<String, List<String>>> sections =
       languageSubtagRegistry.split('%%').skip(1).map<Map<String, List<String>>>(_parseSection).toList();
   for (final Map<String, List<String>> section in sections) {
     assert(section.containsKey('Type'), section.toString());
     final String type = section['Type'].single;
     if (type == 'language' || type == 'region' || type == 'script') {
       assert(section.containsKey('Subtag') && section.containsKey('Description'), section.toString());
       final String subtag = section['Subtag'].single;
       String description = section['Description'].join(' ');
       if (description.startsWith('United '))
         description = 'the $description';
       if (description.contains(kParentheticalPrefix))
         description = description.substring(0, description.indexOf(kParentheticalPrefix));
       if (description.contains(kProvincePrefix))
         description = description.substring(0, description.indexOf(kProvincePrefix));
       if (description.endsWith(' Republic'))
         description = 'the $description';
       switch (type) {
         case 'language':
           _languages[subtag] = description;
           break;
         case 'region':
           _regions[subtag] = description;
           break;
         case 'script':
           _scripts[subtag] = description;
           break;
       }
     }
   }
 }

 String describeLocale(String tag) {
   final List<String> subtags = tag.split('_');
   assert(subtags.isNotEmpty);
   assert(_languages.containsKey(subtags[0]));
   final String language = _languages[subtags[0]];
   String output = language;
   String region;
   String script;
   if (subtags.length == 2) {
     region = _regions[subtags[1]];
     script = _scripts[subtags[1]];
     assert(region != null || script != null);
   } else if (subtags.length >= 3) {
     region = _regions[subtags[2]];
     script = _scripts[subtags[1]];
     assert(region != null && script != null);
   }
   if (region != null)
     output += ', as used in $region';
   if (script != null)
     output += ', using the $script script';
   return output;
 }

 /// Writes the header of each class which corresponds to a locale.
 String generateClassDeclaration(
   LocaleInfo locale,
   String classNamePrefix,
   String superClass,
 ) {
   final String camelCaseName = locale.camelCase();
   return '''

 /// The translations for ${describeLocale(locale.originalString)} (`${locale.originalString}`).
 class $classNamePrefix$camelCaseName extends $superClass {''';
 }

 /// 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"'''
 /// ```
 ///
 /// This function is used by tools that take in a JSON-formatted file to
 /// generate Dart code. For this reason, characters with special meaning
 /// in JSON files. For example, the backspace character (\b) have to be
 /// properly escaped by this function so that the generated Dart code
 /// correctly represents this character:
 /// ```
 /// foo\bar => 'foo\\bar'
 /// foo\nbar => 'foo\\nbar'
 /// foo\\nbar => 'foo\\\\nbar'
 /// foo\\bar => 'foo\\\\bar'
 /// foo\ bar => 'foo\\ bar'
 /// foo$bar = 'foo\$bar'
 /// ```
 String generateString(String value) {
   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
     // Replace backslashes with a placeholder for now to properly parse
     // other special characters.
     .replaceAll('\\', backslash)
     .replaceAll('\$', '\\\$')
     .replaceAll("'", "\\'")
     .replaceAll('"', '\\"')
     .replaceAll('\n', '\\n')
     .replaceAll('\f', '\\f')
     .replaceAll('\t', '\\t')
     .replaceAll('\r', '\\r')
     .replaceAll('\b', '\\b')
     // Reintroduce escaped backslashes into generated Dart string.
     .replaceAll(backslash, '\\\\');

   return "'$value'";
 }

 /// Only used to generate localization strings for the Kannada locale ('kn') because
 /// some of the localized strings contain characters that can crash Emacs on Linux.
 /// See packages/flutter_localizations/lib/src/l10n/README for more information.
 String generateEncodedString(String locale, String value) {
   if (locale != 'kn' || value.runes.every((int code) => code <= 0xFF))
     return generateString(value);

   final String unicodeEscapes = value.runes.map((int code) => '\\u{${code.toRadixString(16)}}').join();
   return "'$unicodeEscapes'";
 }
	// 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 'dart:convert';
	import 'dart:io';

	import 'package:args/args.dart' as argslib;
	import 'package:meta/meta.dart';

	import 'language_subtag_registry.dart';

	typedef HeaderGenerator = String Function(String regenerateInstructions);
	typedef ConstructorGenerator = String Function(LocaleInfo locale);

	int sortFilesByPath (FileSystemEntity a, FileSystemEntity b) {
	return a.path.compareTo(b.path);
	}

	/// Simple data class to hold parsed locale. Does not promise validity of any data.
	@immutable
	class LocaleInfo implements Comparable<LocaleInfo> {
	const LocaleInfo({
	this.languageCode,
	this.scriptCode,
	this.countryCode,
	this.length,
	this.originalString,
	});

	/// Simple parser. Expects the locale string to be in the form of 'language_script_COUNTRY'
	/// where the language is 2 characters, script is 4 characters with the first uppercase,
	/// and country is 2-3 characters and all uppercase.
	///
	/// 'language_COUNTRY' or 'language_script' are also valid. Missing fields will be null.
	///
	/// When `deriveScriptCode` is true, if [scriptCode] was unspecified, it will
	/// be derived from the [languageCode] and [countryCode] if possible.
	factory LocaleInfo.fromString(String locale, { bool deriveScriptCode = false }) {
	final List<String> codes = locale.split('_'); // [language, script, country]
	assert(codes.isNotEmpty && codes.length < 4);
	final String languageCode = codes[0];
	String scriptCode;
	String countryCode;
	int length = codes.length;
	String originalString = locale;
	if (codes.length == 2) {
	scriptCode = codes[1].length >= 4 ? codes[1] : null;
	countryCode = codes[1].length < 4 ? codes[1] : null;
	} else if (codes.length == 3) {
	scriptCode = codes[1].length > codes[2].length ? codes[1] : codes[2];
	countryCode = codes[1].length < codes[2].length ? codes[1] : codes[2];
	}
	assert(codes[0] != null && codes[0].isNotEmpty);
	assert(countryCode == null \|\| countryCode.isNotEmpty);
	assert(scriptCode == null \|\| scriptCode.isNotEmpty);

	/// Adds scriptCodes to locales where we are able to assume it to provide
	/// finer granularity when resolving locales.
	///
	/// The basis of the assumptions here are based off of known usage of scripts
	/// across various countries. For example, we know Taiwan uses traditional (Hant)
	/// script, so it is safe to apply (Hant) to Taiwanese languages.
	if (deriveScriptCode && scriptCode == null) {
	switch (languageCode) {
	case 'zh': {
	if (countryCode == null) {
	scriptCode = 'Hans';
	}
	switch (countryCode) {
	case 'CN':
	case 'SG':
	scriptCode = 'Hans';
	break;
	case 'TW':
	case 'HK':
	case 'MO':
	scriptCode = 'Hant';
	break;
	}
	break;
	}
	case 'sr': {
	if (countryCode == null) {
	scriptCode = 'Cyrl';
	}
	break;
	}
	}
	// Increment length if we were able to assume a scriptCode.
	if (scriptCode != null) {
	length += 1;
	}
	// Update the base string to reflect assumed scriptCodes.
	originalString = languageCode;
	if (scriptCode != null)
	originalString += '_' + scriptCode;
	if (countryCode != null)
	originalString += '_' + countryCode;
	}

	return LocaleInfo(
	languageCode: languageCode,
	scriptCode: scriptCode,
	countryCode: countryCode,
	length: length,
	originalString: originalString,
	);
	}

	final String languageCode;
	final String scriptCode;
	final String countryCode;
	final int length; // The number of fields. Ranges from 1-3.
	final String originalString; // Original un-parsed locale string.

	String camelCase() {
	return originalString
	.split('_')
	.map<String>((String part) => part.substring(0, 1).toUpperCase() + part.substring(1).toLowerCase())
	.join('');
	}

	@override
	bool operator ==(Object other) {
	return other is LocaleInfo
	&& other.originalString == originalString;
	}

	@override
	int get hashCode {
	return originalString.hashCode;
	}

	@override
	String toString() {
	return originalString;
	}

	@override
	int compareTo(LocaleInfo other) {
	return originalString.compareTo(other.originalString);
	}
	}

	/// Parse the data for a locale from a file, and store it in the [attributes]
	/// and [resources] keys.
	void loadMatchingArbsIntoBundleMaps({
	@required Directory directory,
	@required RegExp filenamePattern,
	@required Map<LocaleInfo, Map<String, String>> localeToResources,
	@required Map<LocaleInfo, Map<String, dynamic>> localeToResourceAttributes,
	}) {
	assert(directory != null);
	assert(filenamePattern != null);
	assert(localeToResources != null);
	assert(localeToResourceAttributes != null);

	/// Set that holds the locales that were assumed from the existing locales.
	///
	/// For example, when the data lacks data for zh_Hant, we will use the data of
	/// the first Hant Chinese locale as a default by repeating the data. If an
	/// explicit match is later found, we can reference this set to see if we should
	/// overwrite the existing assumed data.
	final Set<LocaleInfo> assumedLocales = <LocaleInfo>{};

	for (final FileSystemEntity entity in directory.listSync().toList()..sort(sortFilesByPath)) {
	final String entityPath = entity.path;
	if (FileSystemEntity.isFileSync(entityPath) && filenamePattern.hasMatch(entityPath)) {
	final String localeString = filenamePattern.firstMatch(entityPath)[1];
	final File arbFile = File(entityPath);

	// Helper method to fill the maps with the correct data from file.
	void populateResources(LocaleInfo locale, File file) {
	final Map<String, String> resources = localeToResources[locale];
	final Map<String, dynamic> attributes = localeToResourceAttributes[locale];
	final Map<String, dynamic> bundle = json.decode(file.readAsStringSync()) as Map<String, dynamic>;
	for (final String key in bundle.keys) {
	// The ARB file resource "attributes" for foo are called @foo.
	if (key.startsWith('@'))
	attributes[key.substring(1)] = bundle[key];
	else
	resources[key] = bundle[key] as String;
	}
	}
	// Only pre-assume scriptCode if there is a country or script code to assume off of.
	// When we assume scriptCode based on languageCode-only, we want this initial pass
	// to use the un-assumed version as a base class.
	LocaleInfo locale = LocaleInfo.fromString(localeString, deriveScriptCode: localeString.split('_').length > 1);
	// Allow overwrite if the existing data is assumed.
	if (assumedLocales.contains(locale)) {
	localeToResources[locale] = <String, String>{};
	localeToResourceAttributes[locale] = <String, dynamic>{};
	assumedLocales.remove(locale);
	} else {
	localeToResources[locale] ??= <String, String>{};
	localeToResourceAttributes[locale] ??= <String, dynamic>{};
	}
	populateResources(locale, arbFile);
	// Add an assumed locale to default to when there is no info on scriptOnly locales.
	locale = LocaleInfo.fromString(localeString, deriveScriptCode: true);
	if (locale.scriptCode != null) {
	final LocaleInfo scriptLocale = LocaleInfo.fromString(locale.languageCode + '_' + locale.scriptCode);
	if (!localeToResources.containsKey(scriptLocale)) {
	assumedLocales.add(scriptLocale);
	localeToResources[scriptLocale] ??= <String, String>{};
	localeToResourceAttributes[scriptLocale] ??= <String, dynamic>{};
	populateResources(scriptLocale, arbFile);
	}
	}
	}
	}
	}

	void exitWithError(String errorMessage) {
	assert(errorMessage != null);
	stderr.writeln('fatal: $errorMessage');
	exit(1);
	}

	void checkCwdIsRepoRoot(String commandName) {
	final bool isRepoRoot = Directory('.git').existsSync();

	if (!isRepoRoot) {
	exitWithError(
	'$commandName must be run from the root of the Flutter repository. The '
	'current working directory is: ${Directory.current.path}'
	);
	}
	}

	GeneratorOptions parseArgs(List<String> rawArgs) {
	final argslib.ArgParser argParser = argslib.ArgParser()
	..addFlag(
	'overwrite',
	abbr: 'w',
	defaultsTo: false,
	)
	..addFlag(
	'material',
	help: 'Whether to print the generated classes for the Material package only. Ignored when --overwrite is passed.',
	defaultsTo: false,
	)
	..addFlag(
	'cupertino',
	help: 'Whether to print the generated classes for the Cupertino package only. Ignored when --overwrite is passed.',
	defaultsTo: false,
	);
	final argslib.ArgResults args = argParser.parse(rawArgs);
	final bool writeToFile = args['overwrite'] as bool;
	final bool materialOnly = args['material'] as bool;
	final bool cupertinoOnly = args['cupertino'] as bool;

	return GeneratorOptions(writeToFile: writeToFile, materialOnly: materialOnly, cupertinoOnly: cupertinoOnly);
	}

	class GeneratorOptions {
	GeneratorOptions({
	@required this.writeToFile,
	@required this.materialOnly,
	@required this.cupertinoOnly,
	});

	final bool writeToFile;
	final bool materialOnly;
	final bool cupertinoOnly;
	}

	// See also //master/tools/gen_locale.dart in the engine repo.
	Map<String, List<String>> _parseSection(String section) {
	final Map<String, List<String>> result = <String, List<String>>{};
	List<String> lastHeading;
	for (final String line in section.split('\n')) {
	if (line == '')
	continue;
	if (line.startsWith(' ')) {
	lastHeading[lastHeading.length - 1] = '${lastHeading.last}${line.substring(1)}';
	continue;
	}
	final int colon = line.indexOf(':');
	if (colon <= 0)
	throw 'not sure how to deal with "$line"';
	final String name = line.substring(0, colon);
	final String value = line.substring(colon + 2);
	lastHeading = result.putIfAbsent(name, () => <String>[]);
	result[name].add(value);
	}
	return result;
	}

	final Map<String, String> _languages = <String, String>{};
	final Map<String, String> _regions = <String, String>{};
	final Map<String, String> _scripts = <String, String>{};
	const String kProvincePrefix = ', Province of ';
	const String kParentheticalPrefix = ' (';

	/// Prepares the data for the [describeLocale] method below.
	///
	/// The data is obtained from the official IANA registry.
	void precacheLanguageAndRegionTags() {
	final List<Map<String, List<String>>> sections =
	languageSubtagRegistry.split('%%').skip(1).map<Map<String, List<String>>>(_parseSection).toList();
	for (final Map<String, List<String>> section in sections) {
	assert(section.containsKey('Type'), section.toString());
	final String type = section['Type'].single;
	if (type == 'language' \|\| type == 'region' \|\| type == 'script') {
	assert(section.containsKey('Subtag') && section.containsKey('Description'), section.toString());
	final String subtag = section['Subtag'].single;
	String description = section['Description'].join(' ');
	if (description.startsWith('United '))
	description = 'the $description';
	if (description.contains(kParentheticalPrefix))
	description = description.substring(0, description.indexOf(kParentheticalPrefix));
	if (description.contains(kProvincePrefix))
	description = description.substring(0, description.indexOf(kProvincePrefix));
	if (description.endsWith(' Republic'))
	description = 'the $description';
	switch (type) {
	case 'language':
	_languages[subtag] = description;
	break;
	case 'region':
	_regions[subtag] = description;
	break;
	case 'script':
	_scripts[subtag] = description;
	break;
	}
	}
	}
	}

	String describeLocale(String tag) {
	final List<String> subtags = tag.split('_');
	assert(subtags.isNotEmpty);
	assert(_languages.containsKey(subtags[0]));
	final String language = _languages[subtags[0]];
	String output = language;
	String region;
	String script;
	if (subtags.length == 2) {
	region = _regions[subtags[1]];
	script = _scripts[subtags[1]];
	assert(region != null \|\| script != null);
	} else if (subtags.length >= 3) {
	region = _regions[subtags[2]];
	script = _scripts[subtags[1]];
	assert(region != null && script != null);
	}
	if (region != null)
	output += ', as used in $region';
	if (script != null)
	output += ', using the $script script';
	return output;
	}

	/// Writes the header of each class which corresponds to a locale.
	String generateClassDeclaration(
	LocaleInfo locale,
	String classNamePrefix,
	String superClass,
	) {
	final String camelCaseName = locale.camelCase();
	return '''

	/// The translations for ${describeLocale(locale.originalString)} (`${locale.originalString}`).
	class $classNamePrefix$camelCaseName extends $superClass {''';
	}

	/// 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"'''
	/// ```
	///
	/// This function is used by tools that take in a JSON-formatted file to
	/// generate Dart code. For this reason, characters with special meaning
	/// in JSON files. For example, the backspace character (\b) have to be
	/// properly escaped by this function so that the generated Dart code
	/// correctly represents this character:
	/// ```
	/// foo\bar => 'foo\\bar'
	/// foo\nbar => 'foo\\nbar'
	/// foo\\nbar => 'foo\\\\nbar'
	/// foo\\bar => 'foo\\\\bar'
	/// foo\ bar => 'foo\\ bar'
	/// foo$bar = 'foo\$bar'
	/// ```
	String generateString(String value) {
	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
	// Replace backslashes with a placeholder for now to properly parse
	// other special characters.
	.replaceAll('\\', backslash)
	.replaceAll('\$', '\\\$')
	.replaceAll("'", "\\'")
	.replaceAll('"', '\\"')
	.replaceAll('\n', '\\n')
	.replaceAll('\f', '\\f')
	.replaceAll('\t', '\\t')
	.replaceAll('\r', '\\r')
	.replaceAll('\b', '\\b')
	// Reintroduce escaped backslashes into generated Dart string.
	.replaceAll(backslash, '\\\\');

	return "'$value'";
	}

	/// Only used to generate localization strings for the Kannada locale ('kn') because
	/// some of the localized strings contain characters that can crash Emacs on Linux.
	/// See packages/flutter_localizations/lib/src/l10n/README for more information.
	String generateEncodedString(String locale, String value) {
	if (locale != 'kn' \|\| value.runes.every((int code) => code <= 0xFF))
	return generateString(value);

	final String unicodeEscapes = value.runes.map((int code) => '\\u{${code.toRadixString(16)}}').join();
	return "'$unicodeEscapes'";
	}