1 # Copyright (C) 2016 and later: Unicode, Inc. and others. License & terms of use: http://www.unicode.org/copyright.html#License 2 # 3 # Copyright (C) 2006-2009, Google, International Business Machines Corporation and others. All Rights Reserved. 4 # Regex for recognizing RFC 4646 well-formed tags 5 # http://www.rfc-editor.org/rfc/rfc4646.txt 6 # http://tools.ietf.org/html/draft-ietf-ltru-4646bis-21 7 8 # The structure requires no forward references, so it reverses the order. 9 # It uses Java/Perl syntax instead of the old ABNF 10 # The uppercase comments are fragments copied from RFC 4646 11 12 # Note: the tool requires that any real "=" or "#" or ";" in the regex be escaped. 13 14 $alpha = [a-z] ; # ALPHA 15 $digit = [0-9] ; # DIGIT 16 $alphanum = [a-z 0-9] ; # ALPHA / DIGIT 17 $x = x ; # private use singleton 18 $singleton = [a-w y-z] ; # other singleton 19 $s = [-_] ; # separator -- lenient parsers will use [-_] -- strict will use [-] 20 21 # Now do the components. The structure is slightly different to allow for capturing the right components. 22 # The notation (?:....) is a non-capturing version of (...): so the "?:" can be deleted if someone doesn't care about capturing. 23 24 $language = $alpha{2,8} | $alpha{2,3} $s $alpha{3}; 25 26 # ABNF (2*3ALPHA) / 4ALPHA / 5*8ALPHA --- note: because of how | works in regex, don't use $alpha{2,3} | $alpha{4,8} 27 # We don't have to have the general case of extlang, because there can be only one extlang (except for zh-min-nan). 28 29 # Note: extlang invalid in Unicode language tags 30 31 $script = $alpha{4} ; # 4ALPHA 32 33 $region = $alpha{2} | $digit{3} ; # 2ALPHA / 3DIGIT 34 35 $variant = (?: $alphanum{5,8} | $digit $alphanum{3} ) ; # 5*8alphanum / (DIGIT 3alphanum) 36 37 $extension = $singleton (?: $s $alphanum{2,8} )+ ; # singleton 1*("-" (2*8alphanum)) 38 39 $privateUse = $x (?: $s $alphanum{1,8} )+ ; # "x" 1*("-" (1*8alphanum)) 40 41 # Define certain grandfathered codes, since otherwise the regex is pretty useless. 42 # Since these are limited, this is safe even later changes to the registry -- 43 # the only oddity is that it might change the type of the tag, and thus 44 # the results from the capturing groups. 45 # http://www.iana.org/assignments/language-subtag-registry 46 # Note that these have to be compared case insensitively, requiring (?i) below. 47 48 $grandfathered = en $s GB $s oed 49 | i $s (?: ami | bnn | default | enochian | hak | klingon | lux | mingo | navajo | pwn | tao | tay | tsu ) 50 | no $s (?: bok | nyn ) 51 | sgn $s (?: BE $s (?: fr | nl) | CH $s de ) 52 | zh $s min $s nan; 53 54 # old: | zh $s (?: cmn (?: $s Hans | $s Hant )? | gan | min (?: $s nan)? | wuu | yue ); 55 # For well-formedness, we don't need the ones that would otherwise pass. 56 # For validity, they need to be checked. 57 58 # $grandfatheredWellFormed = (?: 59 # art $s lojban 60 # | cel $s gaulish 61 # | zh $s (?: guoyu | hakka | xiang ) 62 # ); 63 64 # Unicode locales: but we are shifting to a compatible form 65 # $keyvalue = (?: $alphanum+ \= $alphanum+); 66 # $keywords = ($keyvalue (?: \; $keyvalue)*); 67 68 # We separate items that we want to capture as a single group 69 70 $variantList = $variant (?: $s $variant )* ; # special for multiples 71 $extensionList = $extension (?: $s $extension )* ; # special for multiples 72 73 $langtag = (?: ( $language ) 74 (?: $s ( $script ) )? 40% 75 (?: $s ( $region ) )? 40% 76 (?: $s ( $variantList ) )? 10% 77 (?: $s ( $extensionList ) )? 5% 78 (?: $s ( $privateUse ) )? 5%); 79 80 # Here is the final breakdown, with capturing groups for each of these components 81 # The variants, extensions, grandfathered, and private-use may have interior '-' 82 83 $root = (?i) # case-insensitive 84 (?: 85 $langtag 90% 86 | ( $privateUse ) 5% 87 | ( $grandfathered ) 5%) 88 # (?: \@ $keywords )? 5% 89 ; 90
