in reply to qr for recursive regex?

darisler,
I am not sure why you are looking for a recursive regex here. Instead, I would simply match globally (perhaps as an iterator) and count how many matches I had: 
my @result = $prBoundaryString =~ m{$coord}g;
# check if scalar (@result / 2) % 2 == 1

# or

my $count = 0;
while ($prBoundaryString =~ m{$coord}g) {
    my ($x, $y) = ($1, $2);
    $count++;
}

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Sorry I had to rush this so it is untested and it may not be explained enough but I hope it makes sense.

Cheers - L~R

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Re^2: qr for recursive regex?
by darisler (Initiate) on May 28, 2014 at 19:15 UTC
    The example I posted is simplified - perhaps too much.

    I really want repetition, not recursion, but ran into roadblock with perl behaviour of only returning the last matches. Here is what I first tried, it only returns the last coordinate pair, which is documented behaviour. 

    #!/usr/bin/env perl

use v5.16;
use strict;


my $prBoundaryString = <<endPrBoundary;
'( (0.01 0.02) (0.0 1328.23) (0.03 0.04) )
endPrBoundary

say "prBoundaryString=$prBoundaryString";

   my ($coord,$coords);

   $coord = qr{
      \(\s*
         (?<x>[\-\.0-9]+)\s+ 
         (?<y>[\-\.0-9]+)\s*
      \)\s*
   }x;

   $coords = qr{
   (
      ( $coord )+
   )
   }x;

   $prBoundaryString =~ m{
       \'\(\s*\s*
       $coords
       \)\s*$
   }x || die "parsePrBoundary: Error parsing prBoundary";

   say "-x0=$-{x}[0]";
   say "-y0=$-{y}[0]";
   say "-x1=$-{x}[1]";
   say "-y1=$-{y}[1]";
   say "-x2=$-{x}[2]";
   say "-y2=$-{y}[2]";

    [download]
    output: - it only gets the last coordinate. 
    prBoundaryString='( (0.01 0.02) (0.0 1328.23) (0.03 0.04) )

-x0=0.03
-y0=0.04
-x1=
-y1=
-x2=
-y2=

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[reply]
[d/l]
[select]
      darisler,
      If you use a regex with the global modifier in scalar context, you will get an iterator allowing you to go through each set of matches one at a time (like one of the examples above): 
      while ($str =~ m{$your_regex}g) {
    my ($x, $y) = ($1, $2);
    # This loop will repeat for as many matches as are in $str
}

      [download]

      Cheers - L~R

[reply]
[d/l]

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