while ( my $token = $p->get_token ) {
    if ($token->is_text) {
        if (length($token->return_text) + $total <= 200) {
            $doc2 .= $token->return_text;
            $total += length($token->return_text);
        }
        else {
            for (split / /, $token->return_text) {
                if ($total + length($_) <= 200) {
                    $doc2 .= $_ . ' ';
                    $total += length($_) + 1;
                }
                else {
                    last;  ## THIS ONLY EXITS THE FOR LOOP
                }          ## So this block runs over the
            }              ## entire remainder of the post
            chop($doc2) if $doc2 =~ /\s$/;
        }
    }
    else {
        $doc2 .= $token->as_is;
    }
}
[download]

• Rather than calling the same "return_text" method so many times, I'd rather use it once to set a local variable (and having just read the TokeParser::Simple docs, it seems that "return_text" is depricated anyway -- use "as_is" in all cases).
• The for loop uses a split on single space -- not what the OP intended -- but this leads to a question about the OP's stated goals: Would you want every input string of /\s{1,}/ to be represented (and counted) as a single space in the output string? (Myself, I would think "yes".)

So here's my version of LTjake's while loop (not tested):

while ( my $token = $p->get_token ) 
{ 
    my $tkntext = $token->as_is;
    $tkntext =~ s/\s+/ /g;  # normalize all whitespace

    if ($token->is_text) {
        if (length($tkntext) + $total <= 200) {
            $doc2 .= $tkntext;
            $total += length($tkntext);
        }
        else {
            my $maxlen = 200 - $total;
            $doc2 .= substr( $tkntext, 0, rindex( $tkntext, ' ', $maxl
+en );
            last;  # this finishes the while loop
        }
    }
    else {
        $doc2 .= " $tkntext ";
    }
}
[download]

Ah yes! Good catch graff. The big problem, as you noted was that I was parsing the whole text. Simply adding another last after the chop(...) fixes that. The other was splitting on one space -- normalizing whitespace like you've done fixes that. Lastly, calling return text all those times is really bad like you've noted, so i just assigned it to a var (and used as_is). Now, while i still like yours better, here's an updated version of mine :)

while ( my $token = $p->get_token ) {
    if ($token->is_text) {
        my $text = $token->as_is;
        $text =~ s/\s+/ /g;
        if (length($text) + $total <= 200) {
            $doc2 .= $text;
            $total += length($text);
        }
        else {
            for (split / /, $text) {
                if ($total + length($_) <= 200) {
                    $doc2 .= $_ . ' ';
                    $total += length($_) + 1;
                }
                else {
                    last;
                }
            }
            chop($doc2) if $doc2 =~ /\s$/;
            last;
        }
    }
    else {
        $doc2 .= $token->as_is;
    }
}
[download]

Thanks for the feedback!

Minor fix to yours:

$doc2 .= substr( $tkntext, 0, rindex( $tkntext, ' ', $maxlen );
[download]

Should be:

$doc2 .= substr( $tkntext, 0, rindex( $tkntext, ' ', $maxlen ) );
[download]

it was missing a bracket. =)

--
"To err is human, but to really foul things up you need a computer." --Paul Ehrlich