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lib/List/StackBy.pm  view on Meta::CPAN

our %EXPORT_TAGS = ( 'all' => [ qw(
	stack_by
) ] );

our @EXPORT_OK = ( @{ $EXPORT_TAGS{'all'} } );

our @EXPORT = qw(
  stack_by
);

sub stack_by(&@) {
  my $code = shift;
  my @result;
  my $prev_key;

  for (@_) {
    my $cur_key = $code->( $_ );

    if (not(ref $prev_key)
     or not(defined $cur_key)
     or not(defined $$prev_key)