[Python-ideas] Regular expression algorithms (original) (raw)

Greg Ewing greg.ewing at canterbury.ac.nz
Fri Apr 13 02:12:32 CEST 2007


Josiah Carlson wrote:

a base Thompson NFA will move on to the next state as early as possible, making a* with Thompson analagous to a*? in the Python

Are you sure that's an inherent characteristic of a Thompson NFA?

As I understood it, using a Thompson NFA is no different from building an NFA and converting it to a DFA, except it does the conversion lazily.

And when using a DFA, whether it matches greedily or not depends on how you drive it. If you stop as soon as you reach the first accepting state, it's non-greedy; if you keep going until you can't go any further, it's greedy.

-- Greg



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