You are feel free to use the code I wrote at Why I like functional programming if you like. There are even pointers there on how to extend it to have substantially more sophisticated functionality than Everything does.

I would recommend a couple of minor changes though. Very specifically in the scrub_input function at the bottom the main loop should probably be:

  while ($raw =~ /\G([\w ]*)/g) {
    $scrubbed .= $1;
    my $pos = pos($raw);
    if ($raw =~ /\G($is_handled)/g) {
      $scrubbed .= $handler->{ lc($1) }->(\$raw);
      # See perlre.  If the handler matches something of
      # length 0, it won't match something of length 0
      # the next time through.  So...
      pos($raw) = pos($raw);
    }
    unless (pos($raw)) {
      if (length($raw) == $pos) {
        # EXIT HERE #
        return $scrubbed . $handler->{post}->(\$raw);
      }
      else {
        my $char = substr($raw, $pos, 1);
        pos($raw) = $pos + 1;
        $scrubbed .= &encode_entities($char);
      }
    }
  }
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because at some point you are likely to want to have an optional handler for returns. Something like this:

  sub {
    my $t_ref = shift;
    if ($$t_ref =~ /\G( *)/g) {
      my $indent = $1;
      $indent =~ s/ / /g;
      return "<br>\n$indent";
    }
    else {
      confess("This shouldn't happen");
    }
  }
[download]

That handler will preserve indents properly. (I say optional because some users do not like that kind of autoformatting, so it should be user-configurable.)

Anyways this node will probably make little sense to you without reading the other. Which may take a while to digest...