)

// ValueError is returned by any of the parsing functions when the
// input is well-formed but the respective subtag is not recognized
// as a valid value.
type ValueError interface {
	error

	// Subtag returns the subtag for which the error occurred.
	Subtag() string
}

// Parse parses the given BCP 47 string and returns a valid Tag. If parsing

func RegionalID(t Tag) (id ID, exact bool) {
	return t.locale, t.full == nil
}

// LanguageTag returns t stripped of regional variant indicators.
//
// At the moment this means it is stripped of a regional and variant subtag "rg"
// and "va" in the "u" extension.
func (t Tag) LanguageTag() Tag {
	if t.full == nil {
		return Tag{language: t.language, locale: t.language}
	}
	tt := t.Tag()
	tt.SetTypeForKey("rg", "")

	}
}

// ErrMissingLikelyTagsData indicates no information was available
// to compute likely values of missing tags.
var ErrMissingLikelyTagsData = errors.New("missing likely tags data")

// addLikelySubtags sets subtags to their most likely value, given the locale.
// In most cases this means setting fields for unknown values, but in some
// cases it may alter a value.  It returns an ErrMissingLikelyTagsData error

//	    // locale-specific service.
//	}
//
// The Matcher's Match method can be used to match Tags directly.
//
// Matchers are aware of the intricacies of equivalence between languages, such
// as deprecated subtags, legacy tags, macro languages, mutual
// intelligibility between scripts and languages, and transparently passing
// BCP 47 user configuration.
// For instance, it will know that a reader of Bokmål Danish can read Norwegian

	// Scripts returns the list of supported scripts.
	Scripts() []Script

	// Regions returns the list of supported regions.
	Regions() []Region
}

var (
	// Supported defines a Coverage that lists all supported subtags. Tags
	// always returns nil.
	Supported Coverage = allSubtags{}
)

// TODO:
// - Support Variants, numbering systems.
// - CLDR coverage levels.
// - Set of common tags defined in this package.