class LogMessageParser

class LogMessageParser implements LogMessageParserInterface {
    
    /**
     * {@inheritdoc}
     */
    public function parseMessagePlaceholders(&$message, array &$context) {
        $variables = [];
        $has_psr3 = FALSE;
        if (($start = strpos($message, '{')) !== FALSE && strpos($message, '}') > $start) {
            $has_psr3 = TRUE;
            // Transform PSR3 style messages containing placeholders to
            // \Drupal\Component\Render\FormattableMarkup style.
            $message = preg_replace('/\\{([^\\{}]*)\\}/U', '@$1', $message);
        }
        foreach ($context as $key => $variable) {
            // PSR3 style placeholders.
            if ($has_psr3) {
                // Keys are not prefixed with anything according to PSR3 specs.
                // If the message is "User {username} created" the variable key will be
                // just "username".
                if (str_contains($message, '@' . $key)) {
                    $key = '@' . $key;
                }
            }
            // To be considered a valid placeholder, the key should be in
            // \Drupal\Component\Render\FormattableMarkup style and the variable
            // should be a string, number, or \Stringable object. For historical
            // reasons, Boolean and NULL placeholders are also allowed; NULL
            // placeholders are deprecated and may throw an error in the future.
            // @see https://www.drupal.org/node/3318826
            if (!empty($key) && ($key[0] === '@' || $key[0] === '%' || $key[0] === ':')) {
                if (is_scalar($variable) || is_null($variable) || $variable instanceof \Stringable) {
                    $variables[$key] = $variable;
                }
            }
        }
        return $variables;
    }

}