Skip to content
Permalink
Branch: master
Find file Copy path
Find file Copy path
Fetching contributors…
Cannot retrieve contributors at this time
86 lines (64 sloc) 3.43 KB
# Regex for recognizing RFC 4646 well-formed tags
# http://www.rfc-editor.org/rfc/rfc4646.txt
# http://tools.ietf.org/html/draft-ietf-ltru-4646bis-21
# The structure requires no forward references, so it reverses the order.
# It uses Java/Perl syntax instead of the old ABNF
# The uppercase comments are fragments copied from RFC 4646
# Note: the tool requires that any real "=" or "#" or ";" in the regex be escaped.
$alpha = [a-z] ; # ALPHA
$digit = [0-9] ; # DIGIT
$alphanum = [a-z 0-9] ; # ALPHA / DIGIT
$x = x ; # private use singleton
$singleton = [a-w y-z] ; # other singleton
$s = [-_] ; # separator -- lenient parsers will use [-_] -- strict will use [-]
# Now do the components. The structure is slightly different to allow for capturing the right components.
# The notation (?:....) is a non-capturing version of (...): so the "?:" can be deleted if someone doesn't care about capturing.
$language = $alpha{2,8} | $alpha{2,3} $s $alpha{3};
# ABNF (2*3ALPHA) / 4ALPHA / 5*8ALPHA --- note: because of how | works in regex, don't use $alpha{2,3} | $alpha{4,8}
# We don't have to have the general case of extlang, because there can be only one extlang (except for zh-min-nan).
# Note: extlang invalid in Unicode language tags
$script = $alpha{4} ; # 4ALPHA
$region = $alpha{2} | $digit{3} ; # 2ALPHA / 3DIGIT
$variant = (?: $alphanum{5,8} | $digit $alphanum{3} ) ; # 5*8alphanum / (DIGIT 3alphanum)
$extension = $singleton (?: $s $alphanum{2,8} )+ ; # singleton 1*("-" (2*8alphanum))
$privateUse = $x (?: $s $alphanum{1,8} )+ ; # "x" 1*("-" (1*8alphanum))
# Define certain grandfathered codes, since otherwise the regex is pretty useless.
# Since these are limited, this is safe even later changes to the registry --
# the only oddity is that it might change the type of the tag, and thus
# the results from the capturing groups.
# http://www.iana.org/assignments/language-subtag-registry
# Note that these have to be compared case insensitively, requiring (?i) below.
$grandfathered = en $s GB $s oed
| i $s (?: ami | bnn | default | enochian | hak | klingon | lux | mingo | navajo | pwn | tao | tay | tsu )
| no $s (?: bok | nyn )
| sgn $s (?: BE $s (?: fr | nl) | CH $s de )
| zh $s min $s nan;
# old: | zh $s (?: cmn (?: $s Hans | $s Hant )? | gan | min (?: $s nan)? | wuu | yue );
# For well-formedness, we don't need the ones that would otherwise pass.
# For validity, they need to be checked.
# $grandfatheredWellFormed = (?:
# art $s lojban
# | cel $s gaulish
# | zh $s (?: guoyu | hakka | xiang )
# );
# Unicode locales: but we are shifting to a compatible form
# $keyvalue = (?: $alphanum+ \= $alphanum+);
# $keywords = ($keyvalue (?: \; $keyvalue)*);
# We separate items that we want to capture as a single group
$variantList = $variant (?: $s $variant )* ; # special for multiples
$extensionList = $extension (?: $s $extension )* ; # special for multiples
$langtag = (?: ( $language )
(?: $s ( $script ) )? 40%
(?: $s ( $region ) )? 40%
(?: $s ( $variantList ) )? 10%
(?: $s ( $extensionList ) )? 5%
(?: $s ( $privateUse ) )? 5%);
# Here is the final breakdown, with capturing groups for each of these components
# The variants, extensions, grandfathered, and private-use may have interior '-'
$root = (?i) # case-insensitive
(?:
$langtag 90%
| ( $privateUse ) 5%
| ( $grandfathered ) 5%)
# (?: \@ $keywords )? 5%
;
You can’t perform that action at this time.