InMemoryFileSystemTree

InMemoryFileSystemTree is a in-memory representation of the file-system consisting of nested directories and files.

Motivation

I was trying to create a simple CMS system in C# .NET and use CKEditor along with its plug-in RoxyFileman. I needed to generate a JSON representation of the directory and files structure in certain format. Basically I had to convert this:

[ "root_dir/file0.pdf", "root_dir/dir1/subdir1/file1.txt", "root_dir/dir1/subdir1/file2.jpg", "root_dir/dir2/subdir2/subsubdir3/file3.doc" ]

into this:

[ {"p":"root_dir", "f":"3", "d":"2"}, {"p":"root_dir/dir1", "f":"2", "d":"0"}, {"p":"root_dir/dir2", "f":"5", "d":"1"}, {"p":"root_dir/dir2/subdir1", "f":"9", "d":"0"} ]

Since all the files were stored as the binaries in the database, I needed have some mechanism to pretend that we HAVE such directories structure. I was looking for a way to store binary files in the database where every file had its absolute path which physically did not exist in the file system. I had to provide feature that any file system has out of the box like:

• having unique file names under the same directory
• ability to create nested directories and files in them
• ability to retrieve all the files under specific directory at certain path.

I couldn't find any complete solution for this problem, so I decided to implement In-Memory File-System myself.

Goals

• Being able to create virtual directory structure out of the list of paths to files
• Provide ability to retrieve a list of files located at path provided.
• Not allowing to have same file name at the same directory level

Features

At the moment the following features are implemented:

• Ability to create in-memory file-system tree with file names.
• Retrieving list of file names at certain path.
• Always having a pointer to the topmost directory (the root).

Implementation

At the heart of the system there is the IFileSystemTree interface. This describes the operations that should be provided by every file-system:

public interface IFileSystemTree { Node Root { get; } IEnumerable GetFilesAtPath(string path); void Add(string path, long fileSize, long fileCreatedAt); }

Constraints:

• Independent of the OS, the directory-separator is always /.
• All paths always start with /. This means: there are no relative paths.
• All paths that refer to a directory end with /.
• All paths that refer to a file do not end with /.

Some examples of using InMemoryFileSystemTree:

Operation	Result
Node rootDir = fileSystemTreeObject.Root	{Root: "root_dir"}
fileSystemTreeObject.Add("dir1/subdir1/file1.txt", 512, 1513222570)	void
IEnumerable<Node> files = fsTree.GetFilesAtPath("dir1/subdir1/")	["file1.txt", "file2.txt"]