Implement Eq for Regex #81
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Note that this is just a comparison of the original strings, it's still possible that two different strings result in the same matching behaviour.
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Thanks for the pull request, and welcome! The Rust team is excited to review your changes, and you should hear from @huonw (or someone else) soon. If any changes to this PR are deemed necessary, please add them as extra commits. This ensures that the reviewer can see what has changed since they last reviewed the code. The way Github handles out-of-date commits, this should also make it reasonably obvious what issues have or haven't been addressed. Large or tricky changes may require several passes of review and changes. Please see CONTRIBUTING.md for more information. |
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I don't think there's any feasible way to detect whether two arbitrary expressions match the same set of strings, so I'm OK with this definition. |
| @@ -159,6 +159,14 @@ impl fmt::Debug for Regex { | |||
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| } | |||
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| impl PartialEq for Regex { | |||
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@yorhel Could you please put a doc comment on this impl explaining the definition of equality used? (Something like what you said in your initial comment is just fine.)
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I have one nit, but other than that, looks good! |
(Sorry for the noise, didn't even realize "behaviour" was British spelling)
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Doc added. Thanks for the feedback! |
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Awesome. Good docs! Thanks! |
I looked into it a bit, and yes, it seems to be non-trivial: http://cs.stackexchange.com/q/12267 (that said, it is stated that one can test equality by computing minimal DFAs and comparing). |
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@huonw Yeah, when we get DFAs (#66) then maybe we can expose that sort of operation, but it probably shouldn't be in an impl of Even better, maybe @carllerche's automaton package can do it for us. |
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Automaton currently computes the minimal DFA using hopcroft's algorithm. Of course, there could always be bugs and the lib is still under heavy development 😄 |
ghost
unassigned 
Note that this is just a comparison of the original strings, it's still possible that two different strings result in the same matching behaviour.