LocaleMatcher class Locales

Matches supported locales to the desired locales.

The class caches information for supported locales so it only needs to be calculated once for multiple getBestMatch or isMatch operations.

The matcher uses the CLDR information (see: https://unicode.org/reports/tr35/#LanguageMatching) to determine which LanguageIds are "close" to each other.

If the distance is the same based on the CLDR information, it will favor supported locales which has a similar number of fields set as the desired locale.

If this is till the same it will favor supported locales which are closer to the "default" locale for a language.

Both LanguageIds and LocaleIds or a mix can be used.

Flutter usage

This class can be used to provide an improved localeListResolutionCallback which can be set during construction of MaterialApp:

 ...
  localeListResolutionCallback: (desiredLocales, supportedLocales) {
    if (desiredLocales == null || desiredLocales.isEmpty) return null;
    var languageId = LocaleMatcher(supportedLocales
        .map((l) => LanguageId.parse(l.toLanguageTag())))
        .getBestMatch(
        desiredLocales.map((l) => LanguageId.parse(l.toLanguageTag())))
        .supportedLocale;
    if (languageId == null || languageId.lang == null) return null;
    return supportedLocales.firstWhere((e) =>
    e.languageCode == languageId.lang &&
        e.scriptCode == languageId.script &&
        e.countryCode == languageId.region);
  },
 ...

Constructors

LocaleMatcher(Iterable<LanguageId> supportedLocales, {bool noDefaultLocale = false, LanguageId? defaultLocale, int? threshold, LanguageId? desiredForThreshold, LanguageId? supportedForThreshold})

Create a new LocaleMatcher with specified supportedLocales.

factory

Properties

defaultLocale → LanguageId?

Locale which will be tried first and returned if no matches occur.

final

hashCode → int

The hash code for this object.

no setter, inherited

orderedMaximizedSupportedLocales → List<LanguageId>

The supported locales in the order that they will be matched, with likely sub tags added (maximized form).

final

orderedSupportedLocales → List<LanguageId>

The supported locales in the order that they will be matched.

final

runtimeType → Type

A representation of the runtime type of the object.

no setter, inherited

threshold → int

The threshold for matching; any matches with distance bigger then the threshold will be ignored.

final

Methods

getBestMatch(Iterable<LanguageId> desiredLocales, {bool favorScript = false, bool favorEarlier = true, bool ignoreFallback = false}) → MatchResult

Get the best match from the desiredLocales out of the supportedLocales.

isMatch(LanguageId desiredLocale, LanguageId supportedLocale, {bool favorScript = false, bool ignoreFallback = false}) → bool

Check if the desiredLocale matches the supportedLocale.

noSuchMethod(Invocation invocation) → dynamic

Invoked when a nonexistent method or property is accessed.

inherited

toString() → String

A string representation of this object.

inherited

Operators

operator ==(Object other) → bool

The equality operator.

inherited

Static Methods

getBestCommonLocaleData(Iterable<String> desiredLocales, Iterable<CommonLocaleData> supportedLocales, {bool noDefaultLocale = false}) → CommonLocaleData?

Helper method to select the desiredLocales from a list of supportedLocaless, where the supportedLocales are CommonLocaleData.