private void CleanUpRoute()
{
NameHelper.EnsureValidFilenameCharacters(_parts);
// NB: process all inner special directories of the route segments
// "" -> remove empty segments
// "." -> reference to current folder, remove unless it is the first segment of a relative path
// ".." -> reference parent folder, remove this and parent folder, as long as the parent is not first segment or special too
var ring = _parts.ToRing();
var link = ring.Head.Next; // first item path segment
while (link != ring.Head)
{
Ring.Link previous = link.Previous;
Ring.Link next = link.Next;
switch ((string)link.Value)
{
case "":
ring.RemoveLink(link);
link = next;
break;
case ".":
if (IsRelativePath && previous == ring.Head)
{
link = next;
break;
}
ring.RemoveLink(link);
link = next;
break;
case "..":
if (previous == ring.Head)
{
if (IsRelativePath)
{
link = next;
break;
}
throw new Exception("Attempt to reference parent above absolute root.");
}
if ((string)previous.Value == ".")
{
ring.RemoveLink(previous);
link = next;
break;
}
if ((string)previous.Value == "..")
{
link = next;
break;
}
ring.RemoveLink(previous);
ring.RemoveLink(link);
link = next;
break;
default:
link = link.Next;
break;
}
}
if (_parts.Count < 1)
{
throw new Exception("Empty path is not valid.");
}
if (_parts.Count == 1)
{
if (IsFolderPath && IsAbsolutePath)
{
//a single root folder is allowed.
return;
}
throw new Exception("Empty path is not valid.");
}
// .\ and ..\ required for relative path part[1]
// .\ and ..\ illegal for absolute path[1]
var firstPart = (string)ring.Head.Next.Value;
bool startsWithRelativeSpecialPart = RelativePath.IsRelativeSpecialPart(firstPart);
if (IsAbsolutePath)
{
if (startsWithRelativeSpecialPart)
{
throw new Exception("Not a valid absolute path.");
}
}
else
{
if (!startsWithRelativeSpecialPart)
{
throw new Exception("Not a valid relative path.");
}
}
if ((IsFilePath) && ((IsAbsolutePath && _parts.Count == 1) || (IsRelativePath && _parts.Count == 2)))
{
throw new Exception("No file name specified.");
}
}
