语言标签的正则表达式（由BCP47定义）

Question

我需要language tag定义的BCP 47的正则表达式。

我知道完整的BNF语法在http://www.rfc-editor.org/rfc/bcp/bcp47.txt可用，我可以用它编写自己的语法，但希望那里已经有一种语法。

Answer 1

看起来像这样：

^((?<grandfathered>(en-GB-oed|i-ami|i-bnn|i-default|i-enochian|i-hak|i-klingon|i-lux|
i-mingo|i-navajo|i-pwn|i-tao|i-tay|i-tsu|sgn-BE-FR|sgn-BE-NL|sgn-CH-DE)|(art-lojban|
cel-gaulish|no-bok|no-nyn|zh-guoyu|zh-hakka|zh-min|zh-min-nan|zh-xiang))|((?<language>
([A-Za-z]{2,3}(-(?<extlang>[A-Za-z]{3}(-[A-Za-z]{3}){0,2}))?)|[A-Za-z]{4}|[A-Za-z]{5,8})
(-(?<script>[A-Za-z]{4}))?(-(?<region>[A-Za-z]{2}|[0-9]{3}))?(-(?<variant>[A-Za-z0-9]{5,8}
|[0-9][A-Za-z0-9]{3}))*(-(?<extension>[0-9A-WY-Za-wy-z](-[A-Za-z0-9]{2,8})+))*
(-(?<privateUse>x(-[A-Za-z0-9]{1,8})+))?)|(?<privateUse>x(-[A-Za-z0-9]{1,8})+))$

这里是生成它的代码（在C＃中：

var regular = "(art-lojban|cel-gaulish|no-bok|no-nyn|zh-guoyu|zh-hakka|zh-min|zh-min-nan|zh-xiang)";
var irregular = "(en-GB-oed|i-ami|i-bnn|i-default|i-enochian|i-hak|i-klingon|i-lux|i-mingo|i-navajo|i-pwn|i-tao|i-tay|i-tsu|sgn-BE-FR|sgn-BE-NL|sgn-CH-DE)";
var grandfathered = "(?<grandfathered>" + irregular + "|" + regular + ")";
var privateUse = "(?<privateUse>x(-[A-Za-z0-9]{1,8})+)";
var singleton = "[0-9A-WY-Za-wy-z]";
var extension = "(?<extension>" + singleton + "(-[A-Za-z0-9]{2,8})+)";
var variant = "(?<variant>[A-Za-z0-9]{5,8}|[0-9][A-Za-z0-9]{3})";
var region = "(?<region>[A-Za-z]{2}|[0-9]{3})";
var script = "(?<script>[A-Za-z]{4})";
var extlang = "(?<extlang>[A-Za-z]{3}(-[A-Za-z]{3}){0,2})";
var language = "(?<language>([A-Za-z]{2,3}(-" + extlang + ")?)|[A-Za-z]{4}|[A-Za-z]{5,8})";
var langtag = "(" + language + "(-" + script + ")?" + "(-" + region + ")?" + "(-" + variant + ")*" + "(-" + extension + ")*" + "(-" + privateUse + ")?" + ")";
var languageTag = @"^(" + grandfathered + "|" + langtag + "|" + privateUse + ")$";

Console.WriteLine(languageTag);

我不能保证它的正确性（我可能已经打错了字，但是在附录A中的示例上可以正常工作。

取决于您的环境，您可能需要删除命名的捕获组"?<...>"。

Answer 2

可在PHP中使用的优化版本。

/^(?<grandfathered>(?:en-GB-oed|i-(?:ami|bnn|default|enochian|hak|klingon|lux|mingo|navajo|pwn|t(?:a[oy]|su))|sgn-(?:BE-(?:FR|NL)|CH-DE))|(?:art-lojban|cel-gaulish|no-(?:bok|nyn)|zh-(?:guoyu|hakka|min(?:-nan)?|xiang)))|(?:(?<language>(?:[A-Za-z]{2,3}(?:-(?<extlang>[A-Za-z]{3}(?:-[A-Za-z]{3}){0,2}))?)|[A-Za-z]{4}|[A-Za-z]{5,8})(?:-(?<script>[A-Za-z]{4}))?(?:-(?<region>[A-Za-z]{2}|[0-9]{3}))?(?:-(?<variant>[A-Za-z0-9]{5,8}|[0-9][A-Za-z0-9]{3}))*(?:-(?<extension>[0-9A-WY-Za-wy-z](?:-[A-Za-z0-9]{2,8})+))*)(?:-(?<privateUse>x(?:-[A-Za-z0-9]{1,8})+))?$/Di

Answer 3

Javascript监管重复的命名捕获组，因此您必须将?<privateUse>的第二次使用更改为例如?<privateUse1>。编译为：

/^((?<grandfathered>(en-GB-oed|i-ami|i-bnn|i-default|i-enochian|i-hak|i-klingon|i-lux|i-mingo|i-navajo|i-pwn|i-tao|i-tay|i-tsu|sgn-BE-FR|sgn-BE-NL|sgn-CH-DE)|(art-lojban|cel-gaulish|no-bok|no-nyn|zh-guoyu|zh-hakka|zh-min|zh-min-nan|zh-xiang))|((?<language>([A-Za-z]{2,3}(-(?<extlang>[A-Za-z]{3}(-[A-Za-z]{3}){0,2}))?)|[A-Za-z]{4}|[A-Za-z]{5,8})(-(?<script>[A-Za-z]{4}))?(-(?<region>[A-Za-z]{2}|[0-9]{3}))?(-(?<variant>[A-Za-z0-9]{5,8}|[0-9][A-Za-z0-9]{3}))*(-(?<extension>[0-9A-WY-Za-wy-z](-[A-Za-z0-9]{2,8})+))*(-(?<privateUse>x(-[A-Za-z0-9]{1,8})+))?)|(?<privateUse1>x(-[A-Za-z0-9]{1,8})+))$/