On 31.08.2019 19:45, Markus Elfring wrote:
>>>> +# nested likely/unlikely calls
>>>> + if ($line =~ /\b(?:(?:un)?likely)\s*\(\s*!?\s*(IS_ERR(?:_OR_NULL|_VALUE)?|WARN)/) {
>>>> + WARN("LIKELY_MISUSE",
>>>
>>> How do you think about to use the specification “(?:IS_ERR(?:_(?:OR_NULL|VALUE))?|WARN)”
>>> in this regular expression?
> …
>> IS_ERR
>> (?:_ <- Another atomic group just to show that '_' is a common prefix?
>
> Yes. - I hope that this specification detail can help a bit.
I'm not sure that another pair of brackets for a single char worth it.
>> Usually, Perl interpreter is very good at optimizing such things.
The interpreter optimizes it internally:
echo 'IS_ERR_OR_NULL' | perl -Mre=debug -ne '/IS_ERR(?:_OR_NULL|_VALUE)?/ && print'
Compiling REx "IS_ERR(?:_OR_NULL|_VALUE)?"
Final program:
1: EXACT <IS_ERR> (4)
4: CURLYX[0]{0,1} (16)
6: EXACT <_> (8) <-- common prefix
8: TRIE-EXACT[OV] (15)
<OR_NULL>
<VALUE>
...
>
> Would you like to help this software component by omitting a pair of
> non-capturing parentheses at the beginning?
>
> \b(?:un)?likely\s*
This pair of brackets is required to match "unlikely" and it's
optional in order to match "likely".
Regards,
Denis
