#!/usr/bin/perl

# urlify -- tchrist@perl.com
require 5.002;  # well, or 5.000 if you see below

$urls = '(' . join ('|', qw{
	http
	telnet
	gopher
	file
	wais
	ftp
    } )
. ')';

$ltrs = '\w';
$gunk = '/#~:.?+=&%@!\-';
$punc = '.:?\-';
$any  = "${ltrs}${gunk}${punc}";

while (<>) {
    ## use this if early-ish perl5 (pre 5.002)
    ##  s{\b(${urls}:[$any]+?)(?=[$punc]*[^$any]|\Z)}{<A HREF="$1">$1</A>}goi;
    ## otherwise use this -- it just has 5.002ish comments
    s{
      \b                    # start at word boundary
      (                     # begin $1  {
       $urls     :          # need resource and a colon
       [$any] +?            # followed by on or more
			    #  of any valid character, but
			    #  be conservative and take only
			    #  what you need to....
      )                     # end   $1  }
      (?=                   # look-ahead non-consumptive assertion
       [$punc]*             # either 0 or more puntuation
       [^$any]              #   followed by a non-url char
       |                    # or else
       $                    #   then end of the string
      )
     }{<A HREF="$1">$1</A>}igox;
    print;
}