Hello J.

UPDATE I probably missed your point.. now I see the IP is never reachead but always treated as if it was and hostname. I'll think a bit more about it..

The problem seems to be fixed if you put NAME            ~ [\D]+ but you will fail again with a hostname like 42.perl.org Perhaps a more strict rule definition is needed to tell difference from ip and hostname.

original reply My help can be very limited because I still do not understand Marpa::R2 and I'm just moving my first, baby steps. I dont understand the rank nor the show_progress part (atm). So I reduced the example to something I know (removing the colors).

Is not the hostname coming from your :default        ::= action => [name,values] ? This is what proposed in the synopsis but I find it a bit misleading.

If you see A dice roller system with Marpa::R2 and its prequel First steps with Marpa::R2 and BNF you will see an anonymous hash is used and is populated during the parsing phase. Maybe you can use a pattern like this (then you can check the validity of an IP or of a valid hostname in distinct part of the code).

I ended with the following code that seems to produce the expected result 

#!/usr/bin/env perl
use warnings;
use strict;

use Data::Dumper;
use Marpa::R2;

my $rules = <<'END_OF_GRAMMAR';
    lexeme default  = latm => 1
    
    :default        ::= action => [values]
    <entry>         ::= <op> (SP) <hostaddr4> 
    <op>            ::= 'add' | 'remove'
    
    <ipv4>          ::= NUMBER ('.') NUMBER ('.') NUMBER ('.') NUMBER
    <hostname>      ::= NAME
    
    <hostaddr4>     ::= <ipv4> | <hostname> 
    
    SP              ~ [\s]+    
    NAME            ~ [\S]+
    NUMBER          ~ [\d]+
END_OF_GRAMMAR

my $input = <<'END_OF_INPUT';
add 192.0.2.1
add www.example.org
remove 192.0.2.2
END_OF_INPUT

my $grammar = Marpa::R2::Scanless::G->new({source => \$rules});

for (split /^/m, $input) {
    chomp;
    if (length $_) {
        print "\nPARSING: $_\n";
        
        my $recce = Marpa::R2::Scanless::R->new({
            grammar => $grammar, 
        });
        
        my $value_ref = $grammar->parse( \$_);
        print Dumper $$value_ref;
    }
}

__OUTPUT__

PARSING: add 192.0.2.1
$VAR1 = [
          [
            'add'
          ],
          [
            [
              '192.0.2.1'
            ]
          ]
        ];

PARSING: add www.example.org
$VAR1 = [
          [
            'add'
          ],
          [
            [
              'www.example.org'
            ]
          ]
        ];

PARSING: remove 192.0.2.2
$VAR1 = [
          [
            'remove'
          ],
          [
            [
              '192.0.2.2'
            ]
          ]
        ];

[download]
L*

There are no rules, there are no thumbs..
Reinvent the wheel, then learn The Wheel; may be one day you reinvent one of THE WHEELS.

In reply to Re: Cannot get Marpa::R2 to prioritise one rule over another by Discipulus
in thread Cannot get Marpa::R2 to prioritise one rule over another by Anonymous Monk

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.