Neos\ContentRepository\Domain\Utility\NodePaths::replaceRelativePathElements PHP Method

    public static function replaceRelativePathElements($path)
    {
        $pathSegments = explode('/', $path);
        $absolutePath = '';
        foreach ($pathSegments as $pathSegment) {
            switch ($pathSegment) {
                case '.':
                    continue;
                    break;
                case '..':
                    $absolutePath = NodePaths::getParentPath($absolutePath);
                    break;
                default:
                    $absolutePath = NodePaths::addNodePathSegment($absolutePath, $pathSegment);
                    break;
            }
        }
        return $absolutePath;
    }

 /**
  * Normalizes the given node path to a reference path and returns an absolute path.
  *
  * You should usually use \Neos\ContentRepository\Domain\Service\NodeService::normalizePath()  because functionality could be overloaded,
  * this is here only for low level operations.
  *
  *
  * @see \Neos\ContentRepository\Domain\Service\NodeService::normalizePath()
  * @param $path
  * @param string $referencePath
  * @return string
  */
 public static function normalizePath($path, $referencePath = null)
 {
     if ($path === '.') {
         return $referencePath;
     }
     if (!is_string($path)) {
         throw new \InvalidArgumentException(sprintf('An invalid node path was specified: is of type %s but a string is expected.', gettype($path)), 1357832901);
     }
     if (strpos($path, '//') !== false) {
         throw new \InvalidArgumentException('Paths must not contain two consecutive slashes.', 1291371910);
     }
     if ($path[0] === '/') {
         $absolutePath = $path;
     } else {
         $absolutePath = NodePaths::addNodePathSegment($referencePath, $path);
     }
     $normalizedPath = NodePaths::replaceRelativePathElements($absolutePath);
     return strtolower($normalizedPath);
 }