Parses the IANA language subtag registry into JSON, which can be queried with `jq`

jq-query-notes.md

Parse language subtag registry into JSON

php language-subtag-registry.php > language-subtag-registry.json

Grandfathered or redundant tags with preferred values

This produces all grandfathered tags, with or without a preferredValue, and includes all redundant tags that have a preferredValue.

cat language-subtag-registry.json \
    | jq '
        .records[]
        | select((.type == "redundant" and has("preferredValue")) or .type == "grandfathered")
        | {(.tag): .preferredValue?}
    ' \
    | jq -s -S add

Produces:

{
  "art-lojban": "jbo",
  "cel-gaulish": null,
  "en-GB-oed": "en-GB-oxendict",
  "i-ami": "ami",
  "i-bnn": "bnn",
  "i-default": null,
  "i-enochian": null,
  "i-hak": "hak",
  "i-klingon": "tlh",
  "i-lux": "lb",
  "i-mingo": null,
  "i-navajo": "nv",
  "i-pwn": "pwn",
  "i-tao": "tao",
  "i-tay": "tay",
  "i-tsu": "tsu",
  "no-bok": "nb",
  "no-nyn": "nn",
  "sgn-BE-FR": "sfb",
  "sgn-BE-NL": "vgt",
  "sgn-BR": "bzs",
  "sgn-CH-DE": "sgg",
  "sgn-CO": "csn",
  "sgn-DE": "gsg",
  "sgn-DK": "dsl",
  "sgn-ES": "ssp",
  "sgn-FR": "fsl",
  "sgn-GB": "bfi",
  "sgn-GR": "gss",
  "sgn-IE": "isg",
  "sgn-IT": "ise",
  "sgn-JP": "jsl",
  "sgn-MX": "mfs",
  "sgn-NI": "ncs",
  "sgn-NL": "dse",
  "sgn-NO": "nsl",
  "sgn-PT": "psr",
  "sgn-SE": "swl",
  "sgn-US": "ase",
  "sgn-ZA": "sfs",
  "zh-cmn": "cmn",
  "zh-cmn-Hans": "cmn-Hans",
  "zh-cmn-Hant": "cmn-Hant",
  "zh-gan": "gan",
  "zh-guoyu": "cmn",
  "zh-hakka": "hak",
  "zh-min": null,
  "zh-min-nan": "nan",
  "zh-wuu": "wuu",
  "zh-xiang": "hsn"
}

language-subtag-registry.php

<?php

declare(strict_types=1);

const REGISTRY_URL = 'https://www.iana.org/assignments/language-subtag-registry/language-subtag-registry';

$context = stream_context_create([
    'http' => [
        'user_agent' => 'language-subtag-registry-crawler/0.1',
    ],
]);

$registryFile = fopen(REGISTRY_URL, 'r', false, $context);
$registryData = [];

if ($registryFile === false) {
    exit(1);
}

// Grab the first line from the file, which is the File-Date record.
[, $fileDate] = splitFields((string) fgets($registryFile));
$registryData['file-date'] = $fileDate;
$registryData['records'] = [];

$count = 0;
$previousKey = null;
while (($line = fgets($registryFile)) !== false) {
    $line = rtrim($line);

    if ($line === '%%') {
        if (isset($record)) {
            $registryData['records'][] = $record;
            unset($record);
        }

        if ($count >= 5) {
            //break;
        }

        continue;
    }

    if (!isset($record)) {
        $count++;
        $record = [];
    }

    [$key, $value] = splitFields($line);

    if ($key !== null) {
        $key = prepareKey($key);
    }

    switch ($key) {
        case 'comments':
        case 'description':
        case 'prefix':
            $record[$key][] = $value;
            break;

        case null:
            switch ($previousKey) {
                case 'comments':
                case 'description':
                case 'prefix':
                    // If the value doesn't exist in the array, we'll fall back to a 0.
                    $previousIndex = count($record[$previousKey] ?? [1]) - 1;
                    $record[$previousKey][$previousIndex] = ($record[$previousKey][$previousIndex] ?? '') . ' ' . $value;
                    break;

                case null;
                    // Do nothing if the previous key was null; this shouldn't happen.
                    break;

                default:
                    $record[$previousKey] = ($record[$previousKey] ?? '') . ' ' . $value;
                    break;
            }
            break;

        default:
            $record[$key] = $value;
            break;
    }

    $previousKey = $key ?? $previousKey;
}

fclose($registryFile);

echo json_encode($registryData, JSON_PRETTY_PRINT | JSON_UNESCAPED_SLASHES | JSON_UNESCAPED_UNICODE);
echo "\n";

/**
 * @return array{0: string | null, 1: string}
 */
function splitFields(string $record): array
{
    $fields = array_map('trim', explode(':', $record, 2));

    if (count($fields) === 1) {
        return [null, $fields[0]];
    }

    /** @var array{0: string, 1: string} */
    return $fields;
}

function prepareKey(string $key): string
{
    $key = strtolower($key);
    $key = str_replace('-', ' ', $key);
    $key = ucwords($key);
    $key = str_replace(' ', '', $key);

    return lcfirst($key);
}