[Freeswitch-users] Interesting regex results and timing

[Guillermo Ruiz Camauer]

https://regex101.com/ lets you compare the regular expression under PCRE,
Javascript and Python.
Both PCRE and Python give the Catastrophic Backtracking error.  Javascript
matches on sx... (the first two characters of the test string).

Guillermo



On Thu, Sep 22, 2016 at 5:42 PM, Podrigal, Aron <aronp at guaranteedplus.com>
wrote:

> Python uses its own SRE engine. But it is fully compatible with PCRE. Also
> I tested it with node /Javascript and that produces the same result as in
> python.
>
> It seems like the library does some internal optimization and for the
> misleading false is because of its detection of catastrophic backtracking.
> And yes, that's great!
>
> On Thu, Sep 22, 2016 at 3:17 PM, Brian West <brian at freeswitch.org> wrote:
>
>> What library does python use for regex?  We use libPCRE.
>>
>> On Thu, Sep 22, 2016 at 12:39 PM, Podrigal, Aron <
>> aronp at guaranteedplus.com> wrote:
>>
>>> Hi,
>>>
>>> I just tried and compared regexs with python and freeswitch and the
>>> performance. I found it interesting
>>>
>>> 1) why in freeswitch the following is false
>>> freeswitch at internal> regex sxsssssssssssssssssssssssa|(\S+)+x
>>> false
>>> 2) (Probably the earlier is the answer) how does freeswitch solve this
>>> in less than a second, where in python / node it took around 23 seconds (on
>>> my machine).
>>>
>>>
>>> Thanks.
>>>
>>> --
>>> Aron Podrigal
>>> -
>>> '1000001', '1110010', '1101111', '1101110'   '1010000', '1101111',
>>> '1100100', '1110010', '1101001', '1100111', '1100001', '1101100'
>>>
>>> P: '2b', '31', '33', '34', '37', '34', '35', '38', '36', '30', '39', '39'
>>>
>>>
>>> ____________________________________________________________
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>>>
>>
>>
>>
>> --
>>
>> *Brian West*
>> brian at freeswitch.org
>>
>>
>> *Twitter: @FreeSWITCH , @briankwest*
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>>
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>>
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>>
>> _________________________________________________________________________
>> Professional FreeSWITCH Consulting Services:
>> consulting at freeswitch.org
>> http://www.freeswitchsolutions.com
>>
>> Official FreeSWITCH Sites
>> http://www.freeswitch.org
>> http://confluence.freeswitch.org
>> http://www.cluecon.com
>>
>> FreeSWITCH-users mailing list
>> FreeSWITCH-users at lists.freeswitch.org
>> http://lists.freeswitch.org/mailman/listinfo/freeswitch-users
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>> http://www.freeswitch.org
>>
>
>
>
> --
> Aron Podrigal
> -
> '1000001', '1110010', '1101111', '1101110'   '1010000', '1101111',
> '1100100', '1110010', '1101001', '1100111', '1100001', '1101100'
>
> P: '2b', '31', '33', '34', '37', '34', '35', '38', '36', '30', '39', '39'
>
>
> _________________________________________________________________________
> Professional FreeSWITCH Consulting Services:
> consulting at freeswitch.org
> http://www.freeswitchsolutions.com
>
> Official FreeSWITCH Sites
> http://www.freeswitch.org
> http://confluence.freeswitch.org
> http://www.cluecon.com
>
> FreeSWITCH-users mailing list
> FreeSWITCH-users at lists.freeswitch.org
> http://lists.freeswitch.org/mailman/listinfo/freeswitch-users
> UNSUBSCRIBE:http://lists.freeswitch.org/mailman/options/freeswitch-users
> http://www.freeswitch.org
>



-- 
Guillermo Ruiz Camauer
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