Module: NEU::MODS::LanguageCodes

Defined in:
lib/neu/mods/language_codes.rb

Overview

ISO 639 code -> English language name, for projecting a code-only languageTerm as something a reader (and a Solr facet) can use.

This is the one place a code is translated, on purpose. The alternative -- mapping in each consumer's display layer -- leaves Solr indexing "eng" while the page shows "English", so the language facet reads in codes. One table, read once, keeps the projection, the display and the index agreed.

Roles are deliberately NOT translated here; a MARC relator is a display label, and the label vocabulary belongs to the consumer (see README).

Constant Summary collapse

REGISTRY_PATH =

The Library of Congress ISO 639-2 registry, vendored byte-for-byte from https://www.loc.gov/standards/iso639-2/ISO-639-2_utf-8.txt so its provenance is a diff rather than a claim. Pipe-delimited: alpha3-bibliographic | alpha3-terminologic | alpha2 | English | French. It lives outside lib/*.rb because the English names carry non-ASCII and the source-purity spec holds the Ruby files to ASCII.

File.expand_path("data/iso639-2.txt", __dir__)
TERMS =

Every alpha-3 bibliographic, alpha-3 terminologic and alpha-2 code that the registry defines, each pointing at its English name. MODS records declare authority="iso639-2b" most often, but iso639-1 and the terminologic codes are equally valid, and a lookup table costs the same whether it holds one form or all three.

File.readlines(REGISTRY_PATH, encoding: "bom|utf-8").each_with_object({}) do |line, terms|
  bibliographic, terminologic, alpha2, english = line.chomp.split("|")
  next if english.to_s.empty?

  # The registry lists synonyms in preference order, so "Spanish;
  # Castilian" becomes "Spanish". Rendering every synonym would make a
  # facet value nobody would click.
  name = english.split(";").first.strip
  [bibliographic, terminologic, alpha2].each do |code|
    terms[code] = name unless code.to_s.empty?
  end
end.freeze

Class Method Summary collapse

Class Method Details

.term(code) ⇒ Object

The English name for a code, or the code itself when the registry does not define it. Never returns nil for a present value: an unrecognised code is still what the record says, and dropping it would lose data.



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# File 'lib/neu/mods/language_codes.rb', line 45

def self.term(code)
  key = code.to_s.strip
  return key if key.empty?

  TERMS.fetch(key.downcase, key)
end