protected static function requireFile( $fileName, $className, $prefix )
    {
        $autoloadDir = ezcBase::$packageDir . "autoload/";

        // We need the full path to the fileName. The method file_exists() doesn't
        // automatically check the (php.ini) library paths. Therefore:
        // file_exists( "ezc/autoload/$fileName" ) doesn't work.
        if ( $prefix === 'ezc' && file_exists( "$autoloadDir$fileName" ) )
        {
            $array = require( "$autoloadDir$fileName" );

            if ( is_array( $array) && array_key_exists( $className, $array ) )
            {
                // Add the array to the cache, and include the requested file.
                ezcBase::$autoloadArray = array_merge( ezcBase::$autoloadArray, $array );
                if ( ezcBase::$options !== null && ezcBase::$options->preload && !preg_match( '/Exception$/', $className ) )
                {
                    foreach ( $array as $loadClassName => $file )
                    {
                        if ( $loadClassName !== 'ezcBase' && !class_exists( $loadClassName, false ) && !interface_exists( $loadClassName, false ) && !preg_match( '/Exception$/', $loadClassName ) /*&& !class_exists( $loadClassName, false ) && !interface_exists( $loadClassName, false )*/ )
                        {
                            ezcBase::loadFile( ezcBase::$autoloadArray[$loadClassName] );
                        }
                    }
                }
                else
                {
                    ezcBase::loadFile( ezcBase::$autoloadArray[$className] );
                }
                return true;
            }
        }

        // It is not in components autoload/ dir.
        // try to search in additional dirs.
        foreach ( ezcBase::$repositoryDirs as $repositoryPrefix => $extraDir )
        {
            if ( gettype( $repositoryPrefix ) === 'string' && $repositoryPrefix !== $prefix )
            {
                continue;
            }

            if ( file_exists( $extraDir['autoloadDirPath'] . '/' . $fileName ) )
            {
                $array = array();
                $originalArray = require( $extraDir['autoloadDirPath'] . '/' . $fileName );

                // Building paths.
                // Resulting path to class definition file consists of:
                // path to extra directory with autoload file +
                // basePath provided for current extra directory +
                // path to class definition file stored in autoload file.
                foreach ( $originalArray as $class => $classPath )
                {
                    $array[$class] = $extraDir['basePath'] . '/' . $classPath;
                }

                if ( is_array( $array ) && array_key_exists( $className, $array ) )
                {
                    // Add the array to the cache, and include the requested file.
                    ezcBase::$externalAutoloadArray = array_merge( ezcBase::$externalAutoloadArray, $array );
                    ezcBase::loadExternalFile( ezcBase::$externalAutoloadArray[$className] );
                    return true;
                }
            }
        }

        // Nothing found :-(.
        return false;
    }