Trie with custom insert and delete functions - algorithm

Question

I need to create four custom function for a Trie data structure without changing its O(n) complexity:
makeDir("pathToDir")
make("pathToFile")
delete("pathToDir")
forceDelete("pathToDirOrFile")
makeDir("pathToDir"): adds path to the trie only if it is a valid path
make("pathToFile"): adds path to the trie only if it is a valid path (a file node can't call makeDir() )
delete("pathToDir"): deletes the path from trie only if it has no child dirs
forceDelete("pathToDirOrFile"): deletes path and its child dirs
For example a list of commands would be:
makeDir("\dir");
makeDir("\dir\foo")
makeDir("\dir\foo\lol\ok"); /* incorrect path */
make("\dir\file");
makeDir("\dir\file\abc"); /* file can't have sub dirs */
delete("\dir"); /* has childs, incorrect */
delete("\dir\file");
forceDelete("\dir");
Does anybody have any idea on how to recognize that the node indicates the path of a files? What is the best way to implement these functions?

Answer 1

Validating and splitting the path
It's OS specific, so just pick any library that works with paths for your target system.
The trie
Once you can split a path into pieces, you can build a trie. Keep strings in its edges. For instance, if you have a foo/bar path, there'll be 3 nodes and two edges: the first one (1->2) is marked with foo and the second one (2->3) is marked with bar.
You can store a flag in each node to indicate if it's a regular file or a directory.
To check if a directory is empty, just make sure it's node has no children.
To check if a directory/file can be created, take its base dir (all parts of the path except the last one), check that it exists by traversing your trie from the root and that its node is a directory, not a regular file.
Efficient traversal
You can store edges in hash table that maps a string to a node.