Re: [PATCH 4/5] dts: add `show port info` command to TestPmdShell

[Luca Vizzarro <Luca.Vizzarro@arm.com>]

On 17/04/2024 14:22, Juraj Linkeš wrote:
>> I agree that it looks much better. I gave it a first attempt to come up
>> with a regular expression that is not too complicated and is able to
>> match blocks individually. I've noticed that blocks start with:
>>
>>     \n********* Infos for port X ************
>>
>> but don't have an actual ending delimiter, unlike for the stats.
> 
> Ah, so that's the difference and the reason. I guess the ending
> delimiter is either the start of the next section of the prompt (or
> the end of the string).

Yes, but it's not as trivial unfortunately. In the current code I am 
effectively just finding all the start positions and slice.

>> I'll
>> experiment with some look ahead constructs. The easiest solution is to
>> match everything that is not * ([^*]+) but can we be certain that there
>> won't be any asterisk in the actual information?
> 
> We can't. But we can be reasonably certain there won't be five
> consecutive asterisks, so maybe we can work with that.

We can work with that by using look ahead constructs as mentioned, which 
can be quite intensive. For example:

   /(?<=\n\*).*?(?=\n\*|$)/gs

looks for the start delimiter and for the start of the next block or the 
end. This works perfectly! But it's performing 9576 steps (!) for just 
two ports. The current solution only takes 10 steps in total.