use strict; use warnings; 

my @reps; 
push @reps,{from=>'ZZZ',to=>'456AAA456'}; 
push @reps,{from=>'AAA',to=>'AAA123'}; 
push @reps,{from=>'BBB',to=>'XYZ999'}; 
push @reps,{from=>'DEF',to=>'ANYOTHER'}; 

while (my $line=<DATA>) { 
  chomp $line; 
  for my $rep (@reps){ 
    my $from=$rep->{from}; 
    my $to  =$rep->{to}; 
    $line=~s/\Q$from\E/$to/g; 
    } # rep 
  print $line."\n"; 
  } # line 

__DATA__
AAAA more stuff 
stuff BBB again 
DEF stuff 
|ZZZZ| not as simple as it seems