It is often said that "only Perl can parse Perl". The reason that this is said, and it is true, is that the ecclectic and rich synstax of Perl makes it impossible to generate simple and robust parsing solutions.

The bottom line is quite simple. Without completely parsing a perl script you can't match keywords reliably. The best source code you will find (in pure Perl), that probably does what you want is perltidy. Perltidy is reasonably robust and mature. It has syntax highlighting (if that was what you had in mind) available and obviously a reasonably robust parsing engine.

Just for laughs have a look at this code and pick the comments. Bonus points for a correct answer on snippet 2 

print <<'drom"edary',<<"f#f",<<'=pod',<< ''; #comment
Just another Perl Hacker
drom"edary
#foo
f#f
#bar
=pod
#foo
#too
#you


# is there a comment in the snippet of code below or not??? Blame Abig
+ail 0.0

BEGIN { if ($ARGV [0]) {eval 'sub foo ()  {print}'}
        else           {eval 'sub foo ($) {print}'}
}
$_ = "Just another Perl Hacker\n";
foo /#/;
1;

[download]

cheers

tachyon

s&&rsenoyhcatreve&&&s&n.+t&"$'$`$\"$\&"&ee&&y&srve&&d&&print

In reply to Re: Matching Perl Keywords by tachyon
in thread Matching Perl Keywords 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.