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[8.5] Add locale_is_right_to_left #527

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[8.5] Add locale_is_right_to_left #527

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beacebd
Add locale_is_right_to_left polyfill
alexander-schranz May 26, 2025
667130e
Update Php85.php
alexander-schranz Jun 24, 2025
6154b51
Merge branch '1.x' into feature/locale_is_right_to_lef
alexander-schranz Jun 24, 2025
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5 changes: 5 additions & 0 deletions src/Php85/Php85.php
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Original file line number Diff line number Diff line change
Expand Up @@ -13,6 +13,7 @@

/**
* @author Pierre Ambroise <[email protected]>
* @author Alexander Schranz <[email protected]>
*
* @internal
*/
Expand All @@ -33,4 +34,8 @@ public static function get_exception_handler(): ?callable

return $handler;
}

public static function locale_is_right_to_left(string $locale): bool {
return (bool) preg_match('/^(?:ar|he|fa|ur|ps|sd|ug|ckb|yi|dv|ku_arab|ku-arab)(?:[_-].*)?$/i', $locale);
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I don't think this is the right implementation. What is right to left is a script, not a language. And locales might specify a script explicitly which is not the most likely script.

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@alexander-schranz alexander-schranz May 26, 2025 •
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I see, any suggestions? Sadly the original code does not help here: unicode-org/icu@53dcbe6

  • A script is right-to-left according to the CLDR script metadata
  • which corresponds to whether the script's letters have Bidi_Class=R or AL.

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This is what Gemini provides, let's take inspiration from this snippet?

    function locale_is_right_to_left(string $locale): bool
    {
        // Define the list of RTL scripts within the function scope.
        // These are 4-letter ISO 15924 script codes.
        static $rtlScripts = [
            'Adlm', 'Arab', 'Armi', 'Hebr', 'Mani', 'Mend', 'Nkoo',
            'Phnx', 'Rohg', 'Samr', 'Syrc', 'Thaa',
        ];

        // This is a minimal, hardcoded version of the CLDR "likelySubtags" data.
        // It maps a language code to its most likely SCRIPT code.
        // This list is NOT exhaustive and is the primary weakness of this approach.
        static $languageToLikelyRtlScript = [
            'ar' => 'Arab', // Arabic
            'fa' => 'Arab', // Persian (Farsi)
            'ur' => 'Arab', // Urdu
            'ps' => 'Arab', // Pashto
            'sd' => 'Arab', // Sindhi
            'ug' => 'Arab', // Uyghur
            'ckb' => 'Arab', // Sorani Kurdish
            'he' => 'Hebr', // Hebrew
            'yi' => 'Hebr', // Yiddish
            'dv' => 'Thaa', // Dhivehi
            'nqo' => 'Nkoo', // N'Ko
        ];

        if (empty($locale)) {
            return false;
        }

        // Normalize separators and split the locale into parts.
        $localeParts = preg_split('/[_-]/', $locale);
        $language = strtolower($localeParts[0] ?? '');
        $script = null;

        // Look for an explicit script subtag (always 4 letters).
        foreach ($localeParts as $part) {
            if (strlen($part) === 4 && ctype_alpha($part)) {
                // Capitalize the first letter for standard format (e.g., "Arab", "Latn").
                $script = ucfirst(strtolower($part));
                break;
            }
        }

        // If no explicit script was found, try to infer it from our map.
        if ($script === null) {
            $script = $languageToLikelyScript[$language] ?? null;
        }

        // If we couldn't determine a script, we can't determine direction.
        if ($script === null) {
            // Fallback for languages where the code itself is a strong indicator
            if (in_array($language, ['ar', 'he', 'fa', 'ur', 'ps', 'sd', 'ug', 'ckb', 'yi', 'dv'])) {
                 return true;
            }
            return false;
        }

        // Check if the determined script is in our list of RTL scripts.
        return in_array($script, $rtlScripts, true);
    }
}

}
}
4 changes: 4 additions & 0 deletions src/Php85/bootstrap.php
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Original file line number Diff line number Diff line change
Expand Up @@ -22,3 +22,7 @@ function get_error_handler(): ?callable { return p\Php85::get_error_handler(); }
if (!function_exists('get_exception_handler')) {
function get_exception_handler(): ?callable { return p\Php85::get_exception_handler(); }
}

if (!function_exists('locale_is_right_to_left')) {
function locale_is_right_to_left(string $locale): bool { return p\Php85::locale_is_right_to_left($locale); }
}
19 changes: 19 additions & 0 deletions tests/Php85/Php85Test.php
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Expand Up @@ -78,6 +78,25 @@ public static function provideHandler()
$handler = new TestHandlerInvokable();
yield [$handler, $handler];
}

public function testLocaleIsRightToLeft(): void
{
$this->assertTrue(locale_is_right_to_left('ar'));
$this->assertTrue(locale_is_right_to_left('he'));
$this->assertTrue(locale_is_right_to_left('fa'));
$this->assertTrue(locale_is_right_to_left('ur'));
$this->assertTrue(locale_is_right_to_left('ps'));
$this->assertTrue(locale_is_right_to_left('sd'));
$this->assertTrue(locale_is_right_to_left('ug'));
$this->assertTrue(locale_is_right_to_left('ckb'));
$this->assertTrue(locale_is_right_to_left('yi'));
$this->assertTrue(locale_is_right_to_left('dv'));
$this->assertTrue(locale_is_right_to_left('ku_arab'));
$this->assertTrue(locale_is_right_to_left('ku-arab'));

$this->assertFalse(locale_is_right_to_left('en'));
$this->assertFalse(locale_is_right_to_left('fr'));
}
}

class TestHandler
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