It is hard to imagine what you are trying to achieve without a concrete example. Maybe generating an array of matches from your master string using your first match criteria, then filtering the array using your second match may do what you need. Otherwise I at least need to see a real sample string (keep it short please) and two example match criteria to be much more help.

I am adapting Lingua::Concordance. It takes all occurences of $query and show it with its context in a ordered way.

Here is the code

$text="Oldfield's career began fairly early, playing <1> acoustic guit
+ar in local folk clubs. At this time, he already had two fifteen-minu
+te instrumental pieces in which he would "go through all <2>sorts of 
+moods", precursors to his landmark 1970s' compositions. In his early 
+teens, Oldfield was involved in a 'beat group' <3>playing Shadows-sty
+le music (he has often cited Hank Marvin as a major influence, and wo
+uld later cover The Shadows' song "Wonderful Land")."

$query="in";

    while ( $text =~ /$query/gi ) {

        my $match   = $1;
        my $pos     = pos( $text );
        my $start   = $pos - $self->radius - length( $match );
        my $extract = '';
        
        if ( $start < 0 ) {
        
            $extract = substr( $text, 0, $width + $start + length( $ma
+tch ));
            $extract = ( " " x -$start ) . $extract;
            
        }
        
        else {
        
            $extract = substr( $text, $start, $width + length( $match 
+));
            my $deficit = $width + length( $match ) - length( $extract
+ );
            if ( $deficit > 0 ) { $extract .= ( " " x $deficit ) }
        
        }
        
        push @lines, $extract;
    }
    
[download]

What I am trying to do is to read the <> tag and associate it to the corresponding $extract (for example: "guitar in local folk" seen after <1>)

It's hard to tell exactly what you want to do, but a first guess is that my original suggestion was exactly on the money. Consider:

use strict;
use warnings;
use Lingua::Concordance;

my $text = <<TEXT;
Oldfield's career began fairly early, playing <1> acoustic guitar in l
+ocal folk
clubs. At this time, he already had two fifteen-minute instrumental pi
+eces in
which he would "go through all <2>sorts of moods", precursors to his l
+andmark
1970s' compositions. In his early teens, Oldfield was involved in a 'b
+eat group'
<3>playing Shadows-style music (he has often cited Hank Marvin as a ma
+jor
influence, and would later cover The Shadows' song "Wonderful Land").
TEXT

my $query = 'in';
my $concordance = Lingua::Concordance->new ();

$concordance->radius(25);
$concordance->text($text);
$concordance->query($query);

my @matches = $concordance->lines();
my @pairs;

for my $match (@matches) {
    while ($match =~ /<(\d+)>.*?$query/g) {
        push @pairs, map {[$_, $match]} $1  if $-[0] < $concordance->r
+adius();
    }
}

print "$_->[0]: $_->[1]\n" for @pairs;
[download]

Prints:

1: ng <1> acoustic guitar in local folk clubs. At thi
3:  a 'beat group' <3>playing Shadows-style music (he
[download]

True laziness is hard work

Do you mean something like this?

if( $text =~ /$query/i ) {
    while ( $text =~ /$query/gi ) {
        do_something();
    }
}
elsif( $text =~ /$query_modified/i ) {
    while ( $text =~ /$query_modified/gi ) {
        do_something_different();
    }
}
else {
    ## Is this possible?
}
[download]

Or perhaps:

while ( $text =~ /($query|$query_modified)/gi ) {
    if( $1 eq $query ) {
        do_something();
    }
    else {
        do_something_else();
    }
}
[download]

A good answer to what he asked .. but not what he wanted. XY problem, I think.

my $text = 'perl monks';

my $query = qr{
    (?<M>monk)
    (?(<M>)(?{do_something_different()}))
    |
    (?<P>perl)
    (?(<P>)(?{do_something()}))
}x;

while($text =~ /$query/gi){};

sub do_something{
    print "found perl\n";
}

sub do_something_different{
    print "found monk\n";
}
[download]

It looks like it could be something for me, BUT - excuse my ignorance - waht kind of sintax is this:

my $query = qr{
    (?<M>monk)
    (?(<M>)(?{do_something_different()}))
    |
    (?<P>perl)
    (?(<P>)(?{do_something()}))
}x;
[download]

With perl 5.8.9 it just doesn't work

With perl 5.8.9 it just doesn't work

That is the kind of syntax it is :)

5.8.x is antique and unsupported :)

Welcome to the future :)

595-Named Capture Buffers, perlre#(?<NAME>pattern)