#!/usr/bin/perl

# http://perlmonks.org/?node_id=1212142

use strict;
use warnings;

my %cats = ( blackcat=>5, whitecat=>10,orangecat=>20 );

while(<DATA>)
  {
  print;
  s#([a-zA-Z][A-Za-z_0-9]+)# $cats{$1} // $1 #ge;
  print;
  }

__DATA__
log10(blackcat)*whitecat*(log10(orangecat))

##</code><code>##

log10(blackcat)*whitecat*(log10(orangecat))
log10(5)*10*(log10(20))