Regular expression implementation details

Question

A question that I answered got me wondering:

How are regular expressions implemented in Python? What sort of efficiency guarantees are there? Is the implementation \

Answer 1

Python's re module was based on PCRE, but has moved on to their own implementation.

Here is the link to the C code.

It appears as though the library is based on recursive backtracking when an incorrect path has been taken.

Regular expression and text size n
a?ⁿaⁿ matching aⁿ

Keep in mind that this graph is not representative of normal regex searches.

http://swtch.com/~rsc/regexp/regexp1.html