#!/usr/bin/perl

use 5.010;

use strict;
use warnings;

use YAML;
use Regexp::Grammars;

my $str = <<'EOT';
(root
  (class living_thing
   (spec human
        (prop has_legs))
   (spec bird (prop has_wings))))
EOT

my $parser = qr{
    ^ <List> $

    <rule: List> (?: \( <[MATCH=Atom]>* \) )
    <rule: Atom> <MATCH=List> | <MATCH=Word>
    <token: Word> \w+

}x;

print Dump $/{List} if $str =~ /$parser/;

__END__
---
- root
-
  - class
  - living_thing
  -
    - spec
    - human
    -
      - prop
      - has_legs
  -
    - spec
    - bird
    -
      - prop
      - has_wings

[download]

In reply to Re: recursive algorithm for nested data structures by JavaFan
in thread recursive algorithm for nested data structures 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.