sile 0.14.8

Simon’s Improved Layout Engine
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--
-- Table sorting with language-dependent collation
-- MIT License (c) 2022 SILE organization
--
local icu = require("justenoughicu")

local collatedSort = {
  -- No ICU for language "und", fallback to 'natural' table.sort
  und = function (t, _)
    table.sort(t)
  end
}

setmetatable (collatedSort, {
  __call = function (self, t, options)
    local lang = SILE.settings:get("document.language")
    if self[lang] and type(self[lang]) == "function" then
      -- Allow overriding ICU for some languages, typically "und"
      return self[lang](t, options)
    end

    if self[lang] and type(self[lang]) == "table" then
      -- Allow customizing the default collation options for some languages
      options = options or self[lang]
    end
    -- Be efficient: create the collator once before sorting.
    -- I don't think we need to cache it, still.
    local collator = icu.collation_create(lang, options or {})
    table.sort(t, function (s1, s2)
      return icu.compare(collator, s1, s2)
    end)
    icu.collation_destroy(collator)
  end
})

return collatedSort