Add Locale.fromSubtags and support for scriptCode.

lib/ui/window.dart

@@ -116,9 +116,9 @@ class WindowPadding {
   }
 }
 
-/// An identifier used to select a user's language and formatting preferences,
-/// consisting of a language and a country. This is a subset of locale
-/// identifiers as defined by BCP 47.
+/// An identifier used to select a user's language and formatting preferences.
+/// This represents a [Unicode Language
+/// Identifier](https://www.unicode.org/reports/tr35/#Unicode_language_identifier).
 ///
 /// Locales are canonicalized according to the "preferred value" entries in the
 /// [IANA Language Subtag
@@ -145,12 +145,51 @@ class Locale {
   /// The primary language subtag must not be null. The region subtag is
   /// optional.
   ///
-  /// The values are _case sensitive_, and should match the case of the relevant
-  /// subtags in the [IANA Language Subtag
-  /// Registry](https://www.iana.org/assignments/language-subtag-registry/language-subtag-registry).
-  /// Typically this means the primary language subtag should be lowercase and
-  /// the region subtag should be uppercase.
-  const Locale(this._languageCode, [ this._countryCode ]) : assert(_languageCode != null);
+  /// The subtag values are _case sensitive_ and should be one of the valid
+  /// subtags according to CLDR supplemental data:
+  /// [language](http://unicode.org/cldr/latest/common/validity/language.xml),
+  /// [region](http://unicode.org/cldr/latest/common/validity/region.xml). The
+  /// primary language subtag should be two to three lowercase letters. The
+  /// region region subtag should be two uppercase letters or three digits. See
+  /// the [Unicode Language
+  /// Identifier](https://www.unicode.org/reports/tr35/#Unicode_language_identifier)
+  /// specification.
+  ///
+  /// Validity is not checked by default, but some methods may throw away
+  /// invalid data.
+  ///
+  /// See also: [Locale.create].
+  const Locale(
+    this._languageCode, [
+    this._countryCode,
+  ]) : assert(_languageCode != null),
+       this.scriptCode = null,
+       this._variants = null;
+
+  /// Creates a new Locale object.
+  ///
+  /// The keyword arguments specify the subtags of the Locale.
+  ///
+  /// The subtag values are _case sensitive_ and should be valid subtags
+  /// according to CLDR supplemental data:
+  /// [language](http://unicode.org/cldr/latest/common/validity/language.xml),
+  /// [script](http://unicode.org/cldr/latest/common/validity/script.xml),
+  /// [region](http://unicode.org/cldr/latest/common/validity/region.xml) and
+  /// [variant](http://unicode.org/cldr/latest/common/validity/variant.xml). If
+  /// there is more than one variant, they should be in sorted order. This list
+  /// will be used as-is, and should never again be modified.
+  ///
+  /// Validity is not checked by default, but some methods may throw away
+  /// invalid data.
+  const Locale.create({
+    String language = 'und',
+    String script,
+    String region,
+    List<String> variants,
+  }) : _languageCode = language,
+       scriptCode = script,  // ignore: prefer_initializing_formals, parameter name and member name are different.
+       _countryCode = region,
+       _variants = variants;
 
   /// The primary language subtag for the locale.
   ///
@@ -166,10 +205,10 @@ class Locale {
   /// Locale('he')` and `const Locale('iw')` are equal, and both have the
   /// [languageCode] `he`, because `iw` is a deprecated language subtag that was
   /// replaced by the subtag `he`.
-  String get languageCode => _canonicalizeLanguageCode(_languageCode);
+  String get languageCode => _replaceDeprecatedLanguageSubtag(_languageCode);
   final String _languageCode;
 
-  static String _canonicalizeLanguageCode(String languageCode) {
+  static String _replaceDeprecatedLanguageSubtag(String languageCode) {
     // This switch statement is generated by //flutter/tools/gen_locale.dart
     // Mappings generated for language subtag registry as of 2018-08-08.
     switch (languageCode) {
@@ -255,6 +294,16 @@ class Locale {
     }
   }
 
+  /// The script subtag for the locale.
+  ///
+  /// This can be null.
+  ///
+  /// This is expected to be a valid Unicode Language Identifier script subtag
+  /// that is listed in Unicode CLDR supplemental data:
+  /// http://unicode.org/cldr/latest/common/validity/script.xml. Please see
+  /// constructor documentation.
+  final String scriptCode;
+
   /// The region subtag for the locale.
   ///
   /// This can be null.
@@ -269,10 +318,10 @@ class Locale {
   /// 'DE')` and `const Locale('de', 'DD')` are equal, and both have the
   /// [countryCode] `DE`, because `DD` is a deprecated language subtag that was
   /// replaced by the subtag `DE`.
-  String get countryCode => _canonicalizeRegionCode(_countryCode);
+  String get countryCode => _replaceDeprecatedRegionSubtag(_countryCode);
   final String _countryCode;
 
-  static String _canonicalizeRegionCode(String regionCode) {
+  static String _replaceDeprecatedRegionSubtag(String regionCode) {
     // This switch statement is generated by //flutter/tools/gen_locale.dart
     // Mappings generated for language subtag registry as of 2018-08-08.
     switch (regionCode) {
@@ -286,6 +335,28 @@ class Locale {
     }
   }
 
+  /// The variants subtags for the locale.
+  ///
+  /// Each subtag is expected to be a valid Unicode Language Identifier variant
+  /// subtag that is listed in Unicode CLDR supplemental data:
+  /// http://unicode.org/cldr/latest/common/validity/variants.xml. Please see
+  /// constructor documentation.
+  Iterable<String> get variants {
+    if (_variants == null)
+      return const <String>[];
+    return _variants;
+  }
+
+  /// Variants subtags for the locale.
+  ///
+  /// This can be null.
+  ///
+  /// This is expected to be a sorted list of valid Unicode Language Identifier
+  /// variant subtags that are listed in Unicode CLDR supplemental data:
+  /// http://unicode.org/cldr/latest/common/validity/variants.xml. Please see
+  /// constructor documentation.
+  final List<String> _variants;
+
   @override
   bool operator ==(dynamic other) {
     if (identical(this, other))
@@ -294,23 +365,36 @@ class Locale {
       return false;
     final Locale typedOther = other;
     return languageCode == typedOther.languageCode
-        && countryCode == typedOther.countryCode;
+        && scriptCode == typedOther.scriptCode
+        && countryCode == typedOther.countryCode
+        && _listEquals<String>(_variants, typedOther._variants);
   }
 
-  @override
-  int get hashCode {
-    int result = 373;
-    result = 37 * result + languageCode.hashCode;
-    if (_countryCode != null)
-      result = 37 * result + countryCode.hashCode;
-    return result;
+  bool _listEquals<T>(List<T> a, List<T> b) {
+    if (a == null)
+      return b == null;
+    if (b == null || a.length != b.length)
+      return false;
+    for (int index = 0; index < a.length; index += 1) {
+      if (a[index] != b[index])
+        return false;
+    }
+    return true;
   }
 
+  @override
+  int get hashCode => hashValues(languageCode, scriptCode, countryCode, hashList(_variants));
+
   @override
   String toString() {
-    if (_countryCode == null)
-      return languageCode;
-    return '${languageCode}_$countryCode';
+    final StringBuffer out = StringBuffer(languageCode);
+    if (scriptCode != null)
+      out.write('_$scriptCode');
+    if (_countryCode != null)
+      out.write('_$countryCode');
+    if (_variants != null)
+      out.write('_${_variants.join("_")}');
+    return out.toString();
   }
 }
 

testing/dart/locale_test.dart

@@ -19,4 +19,43 @@ void main() {
     expect(const Locale('iw', 'DD').toString(), 'he_DE');
     expect(const Locale('iw', 'DD'), const Locale('he', 'DE'));
   });
+
+  test('Locale.create', () {
+    expect(const Locale.create().languageCode, 'und');
+    expect(const Locale.create().scriptCode, null);
+    expect(const Locale.create().countryCode, null);
+    expect(const Locale.create().variants, orderedEquals([]));
+
+    expect(const Locale.create(language: 'en').toString(), 'en');
+    expect(const Locale.create(language: 'en').languageCode, 'en');
+    expect(const Locale.create(script: 'Latn').toString(), 'und_Latn');
+    expect(const Locale.create(script: 'Latn').scriptCode, 'Latn');
+    expect(const Locale.create(region: 'US').toString(), 'und_US');
+    expect(const Locale.create(region: 'US').countryCode, 'US');
+    expect(const Locale.create(variants: []).variants,
+           orderedEquals([]));
+    expect(const Locale.create(variants: ['fonipa', 'scouse']).variants,
+           orderedEquals(['fonipa', 'scouse']));
+
+    expect(Locale.create(language: 'es', region: '419').toString(), 'es_419');
+    expect(Locale.create(language: 'es', region: '419').languageCode, 'es');
+    expect(Locale.create(language: 'es', region: '419').countryCode, '419');
+    expect(Locale.create(script: 'Latn', variants: ['fonipa']).toString(), 'und_Latn_fonipa');
+    expect(Locale.create(script: 'Latn', variants: ['fonipa']).scriptCode, 'Latn');
+    expect(Locale.create(script: 'Latn', variants: ['fonipa']).variants,
+           orderedEquals(['fonipa']));
+
+    expect(Locale.create(language: 'zh', script: 'Hans', region: 'CN').toString(), 'zh_Hans_CN');
+  });
+
+  test('Locale equality', () {
+    expect(Locale.create(language: 'en', variants: ['fonipa']),
+           Locale.create(language: 'en', variants: ['fonipa']));
+    expect(Locale.create(language: 'en', variants: ['fonipa']).hashCode,
+           Locale.create(language: 'en', variants: ['fonipa']).hashCode);
+    expect(Locale.create(language: 'en'),
+           isNot(Locale.create(language: 'en', script: 'Latn')));
+    expect(Locale.create(language: 'en').hashCode,
+           isNot(Locale.create(language: 'en', script: 'Latn').hashCode));
+  });
 }