intl/src/exp.js

Polyfill the ECMA-402 Intl API (except collation)

/**
* Defines regular expressions for various operations related to the BCP 47 syntax,
* as defined at http://tools.ietf.org/html/bcp47#section-2.1
*/

// extlang       = 3ALPHA              ; selected ISO 639 codes
//                 *2("-" 3ALPHA)      ; permanently reserved
const extlang = '[a-z]{3}(?:-[a-z]{3}){0,2}';

// language      = 2*3ALPHA            ; shortest ISO 639 code
//                 ["-" extlang]       ; sometimes followed by
//                                     ; extended language subtags
//               / 4ALPHA              ; or reserved for future use
//               / 5*8ALPHA            ; or registered language subtag
const language = '(?:[a-z]{2,3}(?:-' + extlang + ')?|[a-z]{4}|[a-z]{5,8})';

// script        = 4ALPHA              ; ISO 15924 code
const script = '[a-z]{4}';

// region        = 2ALPHA              ; ISO 3166-1 code
//               / 3DIGIT              ; UN M.49 code
const region = '(?:[a-z]{2}|\\d{3})';

// variant       = 5*8alphanum         ; registered variants
//               / (DIGIT 3alphanum)
const variant = '(?:[a-z0-9]{5,8}|\\d[a-z0-9]{3})';

//                                     ; Single alphanumerics
//                                     ; "x" reserved for private use
// singleton     = DIGIT               ; 0 - 9
//               / %x41-57             ; A - W
//               / %x59-5A             ; Y - Z
//               / %x61-77             ; a - w
//               / %x79-7A             ; y - z
const singleton = '[0-9a-wy-z]';

// extension     = singleton 1*("-" (2*8alphanum))
const extension = singleton + '(?:-[a-z0-9]{2,8})+';

// privateuse    = "x" 1*("-" (1*8alphanum))
const privateuse = 'x(?:-[a-z0-9]{1,8})+';

// irregular     = "en-GB-oed"         ; irregular tags do not match
//               / "i-ami"             ; the 'langtag' production and
//               / "i-bnn"             ; would not otherwise be
//               / "i-default"         ; considered 'well-formed'
//               / "i-enochian"        ; These tags are all valid,
//               / "i-hak"             ; but most are deprecated
//               / "i-klingon"         ; in favor of more modern
//               / "i-lux"             ; subtags or subtag
//               / "i-mingo"           ; combination
//               / "i-navajo"
//               / "i-pwn"
//               / "i-tao"
//               / "i-tay"
//               / "i-tsu"
//               / "sgn-BE-FR"
//               / "sgn-BE-NL"
//               / "sgn-CH-DE"
const irregular = '(?:en-GB-oed'
          + '|i-(?:ami|bnn|default|enochian|hak|klingon|lux|mingo|navajo|pwn|tao|tay|tsu)'
          + '|sgn-(?:BE-FR|BE-NL|CH-DE))';

// regular       = "art-lojban"        ; these tags match the 'langtag'
//               / "cel-gaulish"       ; production, but their subtags
//               / "no-bok"            ; are not extended language
//               / "no-nyn"            ; or variant subtags: their meaning
//               / "zh-guoyu"          ; is defined by their registration
//               / "zh-hakka"          ; and all of these are deprecated
//               / "zh-min"            ; in favor of a more modern
//               / "zh-min-nan"        ; subtag or sequence of subtags
//               / "zh-xiang"
const regular = '(?:art-lojban|cel-gaulish|no-bok|no-nyn'
        + '|zh-(?:guoyu|hakka|min|min-nan|xiang))';

// grandfathered = irregular           ; non-redundant tags registered
//               / regular             ; during the RFC 3066 era
const grandfathered = '(?:' + irregular + '|' + regular + ')';

// langtag       = language
//                 ["-" script]
//                 ["-" region]
//                 *("-" variant)
//                 *("-" extension)
//                 ["-" privateuse]
const langtag = language + '(?:-' + script + ')?(?:-' + region + ')?(?:-'
        + variant + ')*(?:-' + extension + ')*(?:-' + privateuse + ')?';

// Language-Tag  = langtag             ; normal language tags
//               / privateuse          ; private use tag
//               / grandfathered       ; grandfathered tags
export let expBCP47Syntax = RegExp('^(?:'+langtag+'|'+privateuse+'|'+grandfathered+')$', 'i');

// Match duplicate variants in a language tag
export let expVariantDupes = RegExp('^(?!x).*?-('+variant+')-(?:\\w{4,8}-(?!x-))*\\1\\b', 'i');

// Match duplicate singletons in a language tag (except in private use)
export let expSingletonDupes = RegExp('^(?!x).*?-('+singleton+')-(?:\\w+-(?!x-))*\\1\\b', 'i');

// Match all extension sequences
export let expExtSequences = RegExp('-'+extension, 'ig');