[cmake-developers] slow regex implementation in RegularExpression

[David Cole]

On Wed, Nov 23, 2011 at 2:03 PM, Bill Hoffman <bill.hoffman at kitware.com> wrote:
> On 11/23/2011 12:51 PM, Brad King wrote:
>>
>> On 11/23/2011 12:48 PM, Brad King wrote:
>>>
>>> On 11/23/2011 12:43 PM, Brad King wrote:
>>>>
>>>> On 11/23/2011 12:34 PM, Alexandru Ciobanu wrote:
>>>>>
>>>>> The regex in question is:
>>>>>     ^[^][:/*?]+\$
>>>
>>>  "To include a literal ] in the list, make it either the first item"
>>
>> It must be the "[:" in this regex that TRE sees as special since it
>> allows expressions like "[:digit:]" inside a bracket expression.
>>
>> Still, this is a case that my proposed policy would pick up.
>>
>> -Brad
>>
> I am still very wary about this policy.  For 99% of folks the current regex
> is just fine.  Making them "eventually" change to get the new regex is
> making them do work that they don't need or want.  I would rather have two
> API's.   I just don't see the big upside of TRE, and I see this causing pain
> for lots and lots of folks if we push them to make the change.  CMake has
> most likely 100,000 or more users at this point.  A change like this could
> easily inflict a man years of effort onto the world, and should not be taken
> lightly.
>
> -Bill
> --
>
> Powered by www.kitware.com
>
> Visit other Kitware open-source projects at
> http://www.kitware.com/opensource/opensource.html
>
> Please keep messages on-topic and check the CMake FAQ at:
> http://www.cmake.org/Wiki/CMake_FAQ
>
> Follow this link to subscribe/unsubscribe:
> http://public.kitware.com/cgi-bin/mailman/listinfo/cmake-developers
>

Big upside:    (quoting from Alexandru Ciobanu's email of Nov. 17th
earlier in this thread)

The impact on the build time is pretty dramatic:
     CMake: 7h39m
     CMake + TRE: 1h06m