Parse::RecDescent is used to create parsers, yet there already exists a parser for URIs. URI and extention URI::QueryParam should do the trick.

Update: Here's an example: 

use URI             qw( );
use URI::QueryParam qw( );

foreach (
   'http://www.perlmonks.org/index.pl?node_id=629153',
   'http://www.perlmonks.org/index.pl?node=Recently%20Active%20Threads
+',
) {
   my $uri = URI->new($_);
   my @node_ids    = $uri->query_param('node_id');
   my @node_titles = $uri->query_param('node');

   if (  (@node_ids && @node_titles)
      || @node_ids    > 2
      || @node_titles > 2
   ) {
      warn("$uri: Error: Bad uri\n");
   }

   if (!@node_ids && !@node_titles) {
      warn("$uri: Warning: Unrecognized uri\n");
      next;
   }

   if (@node_ids) {
      print("$uri: By Id ($node_ids[0])\n");
   }

   if (@node_titles) {
      print("$uri: By Title ($node_titles[0])\n");
   }
}

[download]

In reply to Re^3: Parse::RecDescent for parsing URLs by ikegami
in thread Parse::RecDescent for parsing URLs by artist

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