Transliteration for digits and separators.

Transliterating a string is an expensive business. First the string has to be exploded into its component graphemes. Then for each grapheme we have to map to the equivalent in the other {locale, number_system}. Then we have to reassemble the string.

Effort is made to short circuit where possible. Transliteration is not required for any {locale, number_system} that is the same as {"en", "latn"} since the implementation uses this combination for the placeholders during formatting already. When short circuiting is possible (typically the en-* locales with "latn" number_system - the total number of short circuited locales is 211 of the 537 in CLDR) the overall number formatting is twice as fast than when formal transliteration is required.

Configuring precompilation of digit transliterations

This module includes Cldr.Number.Transliterate.transliterate_digits/3 which transliterates digits between number systems. For example from :arabic to :latn. Since generating a transliteration map is slow, pairs of transliterations can be configured so that the transliteration map is created at compile time and therefore speeding up transliteration at run time.

To configure these transliteration pairs, add the following to your backend configuration:

defmodule MyApp.Cldr do
  use Cldr,
  locale: ["en", "fr", "th"],
  default_locale: "en",
  precompile_transliterations: [{:latn, :thai}, {:arab, :thai}]
end

Where each tuple in the list configures one transliteration map. In this example, two maps are configured: from :latn to :thai and from :arab to :thai.

A list of configurable number systems is returned by Cldr.Number.System.systems_with_digits/0.

If a transliteration is requested between two number pairs that have not been configured for precompilation, a warning is logged.