#!/usr/bin/perl

# http://perlmonks.org/?node_id=1142266

use strict;
use warnings;

my $path = "XX.YY.ZZ";
my $s    = "(ABC | (~dEf & hIJ)) & ~LMn if foo while bar";
my %ignore = map { $_, $_ } qw( if while for );

(my $answer = $s) =~ s/(\w+)/$ignore{$1} || "$path.$1"/ge;

print "$answer\n";