Dynamic regex matching

What does dynamic regex matching even mean? Well, it isn't an official term, but it is a term we use to explain a Regex that uses variables at runtime to generate a specific expression. Assume for a minute that you are working on a document-management system that needs to implement versioning of documents for a company called Acme Corporation. To do this, the system validates that the document has a valid file name.

A business rule states that the file name of any file uploaded on a specific day must be prefixed with acm (for Acme) and today's date in the yyyy-mm-dd format. There can be only text files, Word documents (only .docx), and Excel documents (only .xlsx). Any documents not conforming to this file format are processed by another method that takes care of archive and invalid documents.

The only task that your method needs to perform is to process fresh documents as version one documents.

Note

In a production system, further logic will probably be needed to determine...