Suppose we wish to highlight search terms returned from a user's query. Now, suppose the user has entered a regular expression, all of which must have matched to be returned from the query, but which also contains captured groups in the expression, and we wish to highlight only those terms in the results.

For example:
my $text = 'This is just an arbitrary example of text.';

#ONLY TWO WORDS ARE CAPTURED--WE WANT TO HIGHLIGHT ONLY THOSE
my $query = qr~(?:(?:This)|(?:That)).*?(just).*?(arbitrary).*?$~;

#THIS WOULD HIGHLIGHT THE ENTIRE LINE
$text =~ s~($query)~<span class="highlight">$1</span>~g;

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How could we upgrade that last line to where it highlighted only the expressions that had been properly captured, i.e. "arbitrary" and "just" in this example?

NOTE: For compatibility purposes, it needs to work with Perl 5.12.4. This excludes the use of the @{^CAPTURE} variable that was not made available until Perl 5.25.7.

Blessings,

~Polyglot~

In reply to Highlighting only captured groups from larger regex by Polyglot

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