Re: Raku regex assert doesn't match

Thank you William, that boolean condition check option looks like it is in the 
direction of the answer I sought.

FYI, the reason I spelled out the character class explicitly rather than using 
"<alpha>" was because I wanted it strictly applied to ASCII chars and not 
everything Unicode considers a char, and this seemed the best way to be sure.

-- Darren Duncan

On 2023-07-30 9:30 p.m., William Michels via perl6-users wrote:
> Hi Darren (and Marcel),
> 
> Two different approaches:
> https://docs.raku.org/language/regexes#Conjunction:_&& 
> <https://docs.raku.org/language/regexes#Conjunction:_&&>
> 
>  From the docs:
> /"For example if you have a regex quoted that matches a quoted string, then `/ 
> <quoted> && <-[x]>* /` matches a quoted string that does not contain the 
> character `x`."/
> 
> Second approach :
> https://stackoverflow.com/questions/64909029/is-it-possible-to-do-boolean-assertions-with-raku-regex
> https://docs.raku.org/language/regexes#Regex_Boolean_condition_check 
> 
> Testing "Regex Boolean condition check" with a one-liner:
> 
> ~ % cat  cats_dogs_jays.txt
> cat
> dog
> jay
> null cat
> false dog
> true jay
> ~ % raku -ne 'put $/ if $_ ~~ m:g/ ( <wb> <alpha>+ <wb> ) <!{ $0 eq "null" | 
> "false" | "true" }> /;'  cats_dogs_jays.txt
> cat
> dog
> jay
> cat
> dog
> jay
> 
> 
> HTH, Bill.
> 
> 
> 
>> On Jul 30, 2023, at 08:59, Marcel Timmerman wrote:
>>
>> On 30-07-2023 06:21, Darren Duncan wrote:
>>> Hello, I have a Raku regex question.
>>>
>>> See the following:
>>>
>>>     token nonquoted_alphanumeric_text
>>>     {
>>>         <!before [null | false | true] <wb>>
>>>         <[ A..Z _ a..z ]> <[ 0..9 A..Z _ a..z ]>*
>>>     }
>>>
>>> What I want is for "nonquoted_alphanumeric_text" to match any simple ASCII 
>>> bareword EXCEPT a few special cases indicated in the example.
>>>
>>> I was hoping there might be some better way of specifying this than my example.
>>>
>>> Is there any more direct way in Raku to say, match this pattern initially, 
>>> but if the result equals these exceptional values then treat it as having not 
>>> matched.
>>>
>>> I am looking for a fully declarative solution in the grammar itself, not 
>>> something involving post-processing.
>>>
>>> Thank you.
>>>
>>> -- Darren Duncan
>>>
>> You can try: <|wb><ALPHA><ALNUM>*