https://docs.raku.org/language/regexes#Regex_interpolation gave me some
ideas
Try matching against / (^P\d+) \s+ %products{$0} /
This one also works, in a roundabout way
/ (^P\d+) \s+ {"%products{$0}"} /
-y
On Sun, Jun 14, 2020 at 4:44 PM Joseph Brenner <doom...@gmail.com> wrote:
> In part because of the recent discussion here, I decided to
> play around with using Raku code embedded in a regexp.
> I came up with a contrived example where I was going to
> examine a product listing in a text block to see if the product
> descriptions matched the product codes. The valid associations
> I have in a hash, so I'm (1) matching for product codes; (2)
> using embedded code to look-up the associated description in the hash;
> (3) using the returned description inside the regex.
>
> my %products = ( 'P123' => "Green Labels That Say Magenta",
> 'P666' => 'Darkseid For President Bumpersticker',
> 'P912' => "Corn dogs",
> );
>
> my $text = q:to/END/;
> P123 Viridian Green Label Saying Magenta
> P666 Yoda puppets
> P912 Corn dogs
> END
>
> my @lines = $text.lines;
> say @lines;
>
> for @lines -> $line {
> say "checking line: $line";
> ## This line works, but it's not a complete solution:
> if $line ~~ / (^P\d+) \s+ <{ %products{$0}.subst(/\s+/, '\s', :g) }> / {
> say "Matched, line looks good";
> }
> else {
> say "NO: bad line.";
> }
> }
>
> I'd thought that a line like this would work:
>
> if $line ~~ / (^P\d+) \s+ <{ %products{$0} }> / {
>
> The trouble though is I've got spaces inside the descriptions,
> so if the returned string is treated as a regexp, I get these
> warnings:
>
> Potential difficulties:
> Space is not significant here; please use quotes or :s
> (:sigspace) modifier (or, to suppress this warning, omit the space, or
> otherwise change the spacing)
>
> Reading a bit, I thought this should work
>
> if $line ~~ / (^P\d+) \s+ $( %products{$0} ) / {
>
> That's supposed to use the return string as a literal match.
> Instead I get a lot of strange messages like:
>
> Use of Nil in string context in regex
>
> Flailing around I considered lots of variations like this:
>
> if $line ~~ / (^P\d+) \s+ Q[<{ %products{$0}}>] / {
>
> But I think that ends up treating everything inside the Q[]
> literally, so you never do the hash lookup.
>
> Another thing that might solve this problem is some sort of
> regexp quote function I could use inside the code before
> returning the string, but I don't know what that would be...
>
