First Commit

vendor/symfony/translation/LocaleFallbackProvider.php

@@ -0,0 +1,95 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Symfony\Component\Translation;
+
+use Symfony\Component\Translation\Exception\InvalidArgumentException;
+
+/**
+ * Derives fallback locales based on ICU parent locale information, by shortening locale
+ * sub tags and ultimately by going through a list of configured fallback locales.
+ *
+ * Also provides locale string validation.
+ *
+ * @author Matthias Pigulla <mp@webfactory.de>
+ */
+final class LocaleFallbackProvider
+{
+    /**
+     * @param string[] $localeFallbacks List of fallback locales to add _after_ the ones derived from ICU information
+     *
+     * @throws InvalidArgumentException If a locale contains invalid characters
+     */
+    public function __construct(
+        private array $localeFallbacks = [],
+    ) {
+        foreach ($localeFallbacks as $locale) {
+            self::validateLocale($locale);
+        }
+    }
+
+    /**
+     * @return string[]
+     */
+    public function computeFallbackLocales(string $locale): array
+    {
+        self::validateLocale($locale);
+
+        static $parentLocales;
+        $parentLocales ??= require __DIR__.'/Resources/data/parents.php';
+
+        $originLocale = $locale;
+        $locales = [];
+
+        while ($locale) {
+            if ($parent = $parentLocales[$locale] ?? null) {
+                $locale = 'root' !== $parent ? $parent : null;
+            } elseif (\function_exists('locale_parse')) {
+                $localeSubTags = locale_parse($locale);
+                $locale = null;
+                if (1 < \count($localeSubTags)) {
+                    array_pop($localeSubTags);
+                    $locale = locale_compose($localeSubTags) ?: null;
+                }
+            } elseif ($i = strrpos($locale, '_') ?: strrpos($locale, '-')) {
+                $locale = substr($locale, 0, $i);
+            } else {
+                $locale = null;
+            }
+
+            if (null !== $locale) {
+                $locales[$locale] = $locale;
+            }
+        }
+
+        foreach ($this->localeFallbacks as $fallback) {
+            if ($fallback === $originLocale) {
+                continue;
+            }
+
+            $locales[$fallback] = $fallback;
+        }
+
+        return array_keys($locales);
+    }
+
+    /**
+     * Asserts that the locale is valid, throws an Exception if not.
+     *
+     * @throws InvalidArgumentException If the locale contains invalid characters
+     */
+    public static function validateLocale(string $locale): void
+    {
+        if (!preg_match('/^[a-z0-9@_\.\-]*$/i', $locale)) {
+            throw new InvalidArgumentException(\sprintf('Invalid "%s" locale.', $locale));
+        }
+    }
+}