Function acceptsLanguageOfferBasic

helpers.go:263–276

acceptsLanguageOfferBasic determines if a language tag offer matches a range according to RFC 4647 Basic Filtering. A match occurs if the range exactly equals the tag or is a prefix of the tag followed by a hyphen. The comparison is case-insensitive. Only a single "*" as the entire range is allowed.

(spec, offer string, _ headerParams)

// as the entire range is allowed. Any "*" appearing after a hyphen renders the
// range invalid and will not match.
func acceptsLanguageOfferBasic(spec, offer string, _ headerParams) bool {
	if spec == "*" {
		return true
	}
	if strings.IndexByte(spec, '*') >= 0 {
		return false
	}
	if utils.EqualFold(spec, offer) {
		return true
	}
	return len(offer) > len(spec) &&
		utils.EqualFold(offer[:len(spec)], spec) &&
		offer[len(spec)] == '-'
}

// acceptsLanguageOfferExtended determines if a language tag offer matches a
// range according to RFC 4647 Extended Filtering (§3.3.2).