Re: I need help understanding a match

On 1/12/25 12:59 AM, William Michels via perl6-users wrote:
> ~$ /Users/admin/rakudo/rakudo-2024.09/rakudo-moar-2024.09-01-macos- 
> arm64-clang/bin/raku -e '  \
>     my Str $AltClickHere = lines[0];  \
>     my @AltArray =
>        ($AltClickHere ~~ m:g/
>            download        #literal
>            .*?             #any-character, one-or-more, frugal
>            <?before \>  >  #positive look-ahead, match but dont capture 
> \> angle
>            /).map(*.Str);   \
>     .put for @AltArray;'  todd_test.txt
> download='betterbird-128.6.0esr-bb20.de.linux-x86_64.tar.bz2'
> download='betterbird-128.6.0esr-bb20.en-US.linux-x86_64.tar.bz2'
> download='betterbird-128.6.0esr-bb20.es-AR.linux-x86_64.tar.bz2'
> 
> Hi Todd,
> 
> Well the previous code I sent works with your example, but the code 
> above is better:
> 
> 1. The first token can be simplified to the literal `download`. You 
> could use `[ ^ | download ]`, which would capture everything from `^` 
> the beginning of the string regardless of whether-or-not the string 
> starts with `download`.
> 
> 2. The second token, `.*?`,    matches any-character, one-or-more, 
> frugally.
> 
> 3. The third (original) token, `<?before \> | \h+ >` could be simplified 
> to either `<?before \> >` or `<?before \h+ >`. It says to find the 
> pattern but stop the match before the literal ">" angle or "\h+" one-or- 
> more horizontal whitespace character.
> 
> I hope that helps a bit. Oh yeah, if you want just the quoted download, 
> you could use a positive-lookbehind, `<?after … >`. See below:
> 
> ~$ /Users/wmichels/rakudo/rakudo-2024.09/rakudo-moar-2024.09-01-macos- 
> arm64-clang/bin/raku -e '  \
>     my Str $AltClickHere = lines[0];  \
>     my @AltArray =
>        ($AltClickHere ~~ m:g/
>            <?after download \= >  #positive look-behind, match but dont 
> capture download\=
>            .*?                    #any-character, one-or-more, frugal
>            <?before \>  >         #positive look-ahead, match but dont 
> capture \> angle
>            /).map(*.Str);   \
>     .put for @AltArray;'  todd_test.txt
> 'betterbird-128.6.0esr-bb20.de.linux-x86_64.tar.bz2'
> 'betterbird-128.6.0esr-bb20.en-US.linux-x86_64.tar.bz2'
> 'betterbird-128.6.0esr-bb20.es-AR.linux-x86_64.tar.bz2'
> 
> HTH, Bill.
> 
>> On Jan 11, 2025, at 19:09, ToddAndMargo via perl6-users <perl6- 
>> [email protected]> wrote:
>>
>> Hi All,
>>
>> In another post, Bill gave me a wonderful match that took
>> a ridiculously long line of test and cut out what I wanted
>> and put it into cells of an array.
>>
>> @ClickArray = $ClickPage ~~ m:g/ <?before ^ | download > .*? <?before 
>> \> | \h+ > /;
>>
>> I do not understand what he did.
>>
>> m:g   = match and global
>>
>> <>    = litteral
>>
>> ?     what does this do?
>> ^     what does this do?
>>
>> |     what does this do?
>> \     what does this do
>>
>> \h+ >   what does this do?
>>
>>
>>
>> Yours in confusion.
>> -T
>>
>>
>> In practice:
>>
>>
>> [0] > my Str $x=Q{^[[200~download='betterbird-128.6.0esr- 
>> bb20.de.linux-x86_64.tar.bz2'>    <div class="img bz2"></div>    <div 
>> class="name">        <div class="file fs-1-2 
>> bold">betterbird-128.6.0esr-bb20.de.linux-x86_64.tar.bz2</div> <div 
>> class="data upper size fs-0-7"><span class="bold">Size:</span> 
>> 80.26<span class="fs-0-8 bold">MB</span></div>        <div class="data 
>> upper modified fs-0-7"><span class="bold">Last modified:</span> Tue. 
>> January 7th, 2025 - 10:54pm</div>    </div></a></div><div 
>> class="block"><a href="LinuxArchive/betterbird-128.6.0esr-bb20.en- 
>> US.linux-x86_64.tar.bz2" class="bz2" download='betterbird-128.6.0esr- 
>> bb20.en-US.linux-x86_64.tar.bz2'> <div class="img bz2"></div>    <div 
>> class="name">        <div class="file fs-1-2 
>> bold">betterbird-128.6.0esr-bb20.en-US.linux-x86_64.tar.bz2</div> <div 
>> class="data upper size fs-0-7"><span class="bold">Size:</span> 
>> 80.04<span class="fs-0-8 bold">MB</span></div>        <div class="data 
>> upper modified fs-0-7"><span class="bold">Last modified:</span> Tue. 
>> January 7th, 2025 - 10:42pm</div>    </div>    </a></div><div 
>> class="block"><a href="LinuxArchive/betterbird-128.6.0esr-bb20.es- 
>> AR.linux-x86_64.tar.bz2" class="bz2" download='betterbird-128.6.0esr- 
>> bb20.es-AR.linux-x86_64.tar.bz2'> <div class="img bz2"></div>    <div 
>> class="name">        <div class="file fs-1-2 
>> bold">betterbird-128.6.0esr-bb20.es-AR.linux-x86_64.tar.bz2</div>}
>> download='betterbird-128.6.0esr-bb20.de.linux-x86_64.tar.bz2'>    <div 
>> class="img bz2"></div>    <div class="name">        <div class="file 
>> fs-1-2 bold">betterbird-128.6.0esr-bb20.de.linux-x86_64.tar.bz2</div> 
>>     <div <class="data upper size fs-0-7"><span class="bold">Size:</ 
>> span> 80.26<span class="fs-0-8 bold">MB</span></div>        <div 
>> class="data upper modified fs-0-7"><span class="bold">Last modified:</ 
>> span> Tue. January 7th, 2025 - 10:54pm</div> </div></a></div><div 
>> class="block"><a href="LinuxArchive/betterbird-128.6.0esr-bb20.en- 
>> US.linux-x86_64.tar.bz2" class="bz2" download='betterbird-128.6.0esr- 
>> bb20.en-US.linux-x86_64.tar.bz2'> <div class="img bz2"></div>    <div 
>> class="name">        <div class="file fs-1-2 
>> bold">betterbird-128.6.0esr-bb20.en-US.linux-x86_64.tar.bz2</div> <div 
>> class="data upper size fs-0-7"><span class="bold">Size:</span> 
>> 80.04<span class="fs-0-8 bold">MB</span></div>        <div class="data 
>> upper modified fs-0-7"><span class="bold">Last modified:</span> Tue. 
>> January 7th, 2025 - 10:42pm</div>    </div>    </a></div><div 
>> class="block"><a href="LinuxArchive/betterbird-128.6.0esr-bb20.es- 
>> AR.linux-x86_64.tar.bz2" class="bz2" download='betterbird-128.6.0esr- 
>> bb20.es-AR.linux-x86_64.tar.bz2'> <div class="img bz2"></div>    <div 
>> class="name">        <div class="file fs-1-2 
>> bold">betterbird-128.6.0esr-bb20.es-AR.linux-x86_64.tar.bz2</div>
>>
>>
>> [1] > my @y = $x ~~ m:g/ <?before ^ | download > .*? <?before \> | \h+ 
>> > /;
>>
>> [｢download='betterbird-128.6.0esr-bb20.de.linux-x86_64.tar.bz2'｣ 
>> ｢download='betterbird-128.6.0esr-bb20.en-US.linux-x86_64.tar.bz2'｣ 
>> ｢download='betterbird-128.6.0esr-bb20.es-AR.linux-x86_64.tar.bz2'｣]
>>
>>
>> [2] > for @y -> $Line  { print $Line ~ "\n"; }
>>
>> download='betterbird-128.6.0esr-bb20.de.linux-x86_64.tar.bz2'
>> download='betterbird-128.6.0esr-bb20.en-US.linux-x86_64.tar.bz2'
>> download='betterbird-128.6.0esr-bb20.es-AR.linux-x86_64.tar.bz2'
>>
> 


Thank you!  Now to create a keeper out of it!