DmitryDulepov\Realurl\Configuration\ConfigurationReader::getConfigurationKeyByDomainDecode PHP Method

    protected function getConfigurationKeyByDomainDecode($configurationKey)
    {
        $globalConfig =& $GLOBALS['TYPO3_CONF_VARS']['EXTCONF']['realurl'];
        foreach ($globalConfig['_DOMAINS']['decode'] as $domainName => $configuration) {
            $checkThisConfiguration = false;
            if ($domainName[0] == '/') {
                // Regular expression, match only main host name
                if (@preg_match($domainName, $this->hostName)) {
                    $checkThisConfiguration = true;
                }
            } elseif ($domainName === $this->hostName || $domainName === $this->alternativeHostName) {
                $checkThisConfiguration = true;
            }
            if ($checkThisConfiguration) {
                if (isset($configuration['useConfiguration']) && isset($globalConfig[$configuration['useConfiguration']])) {
                    $configurationKey = $configuration['useConfiguration'];
                    $this->domainConfiguration = $configuration;
                }
                if (is_array($configuration['GETvars'])) {
                    foreach ($configuration['GETvars'] as $getVar => $getVarValue) {
                        $this->getVarsToSet[$getVar] = $getVarValue;
                    }
                }
                break;
            }
        }
        return $configurationKey;
    }