OO File System

The assignment is to design and implement an in-memory file system. This file-system consists of 4 types of entities: Drives, Folders, Text files, Zip files.

These entities, very much like their “real” file-system counterparts, obey the following relations. a. A folder, a drive or a zip file, may contain zero to many other folders, or files (text or zip). b. A text file does not contain any other entity. c. A drive is not contained in any entity. d. Any non-drive entity must be contained in another entity. If entity A contains entity B then we say that A is the parent of B.

Every entity has the following properties:

1. Type – The type of the entity (one of the 4 type above).
2. Name - An alphanumeric string. Two entities with the same parent cannot have the same name. Similarly, two drives cannot have the same name.
3. Path – The concatenation of the names of the containing entities, from the drive down to and including the entity. The names are separated by ‘\’.
4. A text file has a property called Content which is a string.
5. Size – an integer defined as follows:
6. For a text file – it is the length of its content.
7. For a drive or a folder, it is the sum of all sizes of the entities it contains.
8. For a zip file, it is one half of the sum of all sizes of the entities it contains.

The system should be capable of supporting file-system like operations

1. Create – Creates a new entity. Arguments: Type, Name, Path of parent. Exceptions: Path not found; Path already exists; Illegal File System Operation (if any of the rules a-d above is violated).

2. Delete – Deletes an existing entity (and all the entities it contains). Arguments: Path Exceptions: Path not found.

3. Move – Changing the parent of an entity. Arguments: Source Path, Destination Path. Exceptions: Path not found; Path already exists, Illegal File System Operation.

4. WriteToFile – Changes the content of a text file. Arguments: Path, Content Exceptions: Path not found; Not a text file.

Tasks: a. Come up with the design for this system. Full implementation is not required, but only to the level which you feel is a “proof of concept”. b. Show a sketch of implementation of the Move operation. c. Explicitly implement the property Size.

Choose whatever OO language you are comfortable with – preferably Java or C#.