Convert a Python Date, Time or DateTime string into Associated Format

The Problem

I am working on a python application that analyzes user input, and attempts to work out how to regenerate it. Part of this is ingesting dates / times / datetimes of arbitrary formats as strings, and detecting what the format is.

Example

• Given an input date of 23-09-1992, I should be able to produce the format %d-%m-%Y
• Given an input time of 13:09, I should be able to produce the format %h:%m

Ideally this should work generically, so I can provide any common date, time or datetime string and it will deduce the format for me.

My Attempts

• I attempted to build a list of known datetime / date / time formats but quickly realised I could be here until I die, so decided against it.

• I have reached into the code of dateutils.parser to see if something in there can help, but I don't think it can. It does not look like a format is generated, rather the datetime object is built directly.