+sub pp_flip {
+ my ($self, $op) = @_;
+
+ $op = $op->first;
+ return 'list' if name($op) ne 'range';
+
+ my $begin = $op->first;
+ if (name($begin) eq 'const') {
+ my $end = $begin->sibling;
+ if (name($end) eq 'const') {
+ $begin = $self->const_sv($begin);
+ $end = $self->const_sv($end);
+ no warnings 'numeric';
+ return int(${$end->object_2svref}) - int(${$begin->object_2svref}) + 1;
+ } else {
+ my ($p, $r) = $self->expect_return($end);
+ return $p => 1 if $r;
+ }
+ } else {
+ my ($p, $r) = $self->expect_return($begin);
+ return $p => 1 if $r;
+ }
+
+ return 'list'
+}
+