}
return $code;
}
+
+ /**
+ * Get the normalised IETF language tag
+ * See unit test for examples.
+ * See mediawiki.language.bcp47 for the JavaScript implementation.
+ *
+ * @param string $code The language code.
+ * @return string The language code which complying with BCP 47 standards.
+ *
+ * @since 1.31
+ */
+ public static function bcp47( $code ) {
+ $codeSegment = explode( '-', $code );
+ $codeBCP = [];
+ foreach ( $codeSegment as $segNo => $seg ) {
+ // when previous segment is x, it is a private segment and should be lc
+ if ( $segNo > 0 && strtolower( $codeSegment[( $segNo - 1 )] ) == 'x' ) {
+ $codeBCP[$segNo] = strtolower( $seg );
+ // ISO 3166 country code
+ } elseif ( ( strlen( $seg ) == 2 ) && ( $segNo > 0 ) ) {
+ $codeBCP[$segNo] = strtoupper( $seg );
+ // ISO 15924 script code
+ } elseif ( ( strlen( $seg ) == 4 ) && ( $segNo > 0 ) ) {
+ $codeBCP[$segNo] = ucfirst( strtolower( $seg ) );
+ // Use lowercase for other cases
+ } else {
+ $codeBCP[$segNo] = strtolower( $seg );
+ }
+ }
+ $langCode = implode( '-', $codeBCP );
+ return $langCode;
+ }
}