use strict;

my (@Keys,@KeysNeed,@KeysAvoid);
my $keywords = qq(word +"my phrase" -"my phrase's mom" +other keywords);

while ($keywords) {
  $keywords =~ s/^\s*([+-]*)(((["'])(.*?)\4)|\S+)\s*//;
  my $cat = $1;
  my $keyword = $2;

  $keyword =~ s/^[^\w\s]+//g; # Strip special chars from the ends
  $keyword =~ s/[^\w\s]+$//g;
  next unless $keyword;

  if ($cat =~ /\+/) {
    push @KeysNeed, $keyword;
  }
  elsif ($cat =~ /\-/) {
    push @KeysAvoid, $keyword;
  }
  else {
    push @Keys, $keyword;
  }
}

print "KEYS NEEDED: @KeysNeed\n";
print "KEYS TO AVOID: @KeysAvoid\n";
print "KEYS: @Keys\n";

# prints:
# KEYS NEEDED: my phrase other
# KEYS TO AVOID: my phrase's mom
# KEYS: word keywords