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-- RFC 5646 Section 2.1
local lpeg = require "lpeg"
local core = require "lpeg_patterns.core"
local C = lpeg.C
local P = lpeg.P
local R = lpeg.R
local Cg = lpeg.Cg
local Ct = lpeg.Ct
local Cmt = lpeg.Cmt
local M = {}
local alphanum = core.ALPHA + core.DIGIT
local extlang = core.ALPHA * core.ALPHA * core.ALPHA * -#alphanum
* (P"-" * core.ALPHA * core.ALPHA * core.ALPHA * -#alphanum)^-2
local language = Cg(core.ALPHA * core.ALPHA * core.ALPHA * core.ALPHA * core.ALPHA * core.ALPHA^-3, "language")
+ Cg(core.ALPHA * core.ALPHA * core.ALPHA * core.ALPHA, "language")
+ Cg(core.ALPHA * core.ALPHA * core.ALPHA^-1, "language") * (P"-" * Cg(extlang, "extlang"))^-1
local script = core.ALPHA * core.ALPHA * core.ALPHA * core.ALPHA
* -#alphanum -- Prevent intepretation of a 'variant'
local region = (
core.ALPHA * core.ALPHA
+ core.DIGIT * core.DIGIT * core.DIGIT
) * -#alphanum -- Prevent intepretation of a 'variant'
local variant = core.DIGIT * alphanum * alphanum * alphanum
+ alphanum * alphanum * alphanum * alphanum * alphanum * alphanum^-3
local singleton = core.DIGIT + R("AW", "YZ", "aw", "yz")
local extension = C(singleton) * Ct((P"-" * (alphanum*alphanum*alphanum^-6 / string.lower))^1)
M.privateuse = P"x" * Ct((P"-" * C(alphanum*alphanum^-7))^1)
M.langtag = language
* (P"-" * Cg(script, "script"))^-1
* (P"-" * Cg(region, "region"))^-1
* Cg(Ct((P"-" * C(variant))^1), "variant")^-1
* Cg(Cmt(Ct((P"-" * Ct(extension))^1), function(_, _, c)
-- Can't use a fold with rawset as we want the pattern to not match if there is a duplicate extension
local r = {}
for _, v in ipairs(c) do
local a, b = v[1], v[2]
if r[a] then
-- duplicate extension
return false
end
r[a] = b
end
return true, r
end), "extension")^-1
* (P"-" * Cg(M.privateuse, "privateuse"))^-1
local irregular = P"en-GB-oed"
+ P"i-ami"
+ P"i-bnn"
+ P"i-default"
+ P"i-enochian"
+ P"i-hak"
+ P"i-klingon"
+ P"i-lux"
+ P"i-mingo"
+ P"i-navajo"
+ P"i-pwn"
+ P"i-tao"
+ P"i-tay"
+ P"i-tsu"
+ P"sgn-BE-FR"
+ P"sgn-BE-NL"
+ P"sgn-CH-DE"
M.Language_Tag = C((M.langtag
+ M.privateuse
+ irregular) / function() end) -- capture the whole tag. throws away decomposition
return M
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