Here is non-regexp solution. It validates input in addition to the main task. 

sub splitlong {
    my $text = shift;
    my @result;
    my ($cnt, $inside) = (0, 0);
    for (split //, $text) {
        ($inside = 0), next if $inside and $_ eq ']';
        $inside = 1 if !$inside and $_ eq '[';
        next if $inside;
        $cnt = /\s/s ? 0 : $cnt + 1;
        ($cnt = 0), push @result, '-' if $cnt > 3;
    }
    continue {
        push @result, $_;
    }
    warn "invalid input: $text" if $inside;
    return join '', @result;
}

my $text = 'ju[color=1]s[/color]t a sam[color=2]p[/color]le';

print splitlong($text);

[download]

In reply to Re^3: Problem: how to split long words by ccn
in thread Problem: how to split long words by nikos

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.