s { ([^"']*)?   # non quoted part
   ("[^"]*")?   # doublequoted
   ('[^']*')?   # singlequoted 
  }
  {
    my($x, $y, $z) = map {defined() ? $_ : ''} $1, $2, $3;
    $x =~ s/(?<!\S)(?=\S)/A/g;
    $x . $y . $z
  }xge;