File Coverage

blib/lib/Hash/MoreUtils.pm

Criterion	Covered	Total	%
statement	96	97	98.9
branch	20	24	83.3
condition			n/a
subroutine	20	20	100.0
pod	10	10	100.0
total	146	151	96.6

package Hash::MoreUtils;

use strict;
use warnings;
use vars qw(@ISA @EXPORT @EXPORT_OK %EXPORT_TAGS $VERSION);
use Scalar::Util qw(blessed);

require Exporter;

@ISA = qw(Exporter);

%EXPORT_TAGS = (
    all => [
        qw(slice slice_def slice_exists slice_grep),
        qw(slice_map slice_def_map slice_exists_map slice_grep_map),
        qw(hashsort safe_reverse)
    ],
);

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

$VERSION = '0.05';

=head1 NAME

Hash::MoreUtils - Provide the stuff missing in Hash::Util

=head1 SYNOPSIS

  use Hash::MoreUtils qw(slice slice_def slice_exists slice_grep
                         hashsort
                        );

=head1 DESCRIPTION

Similar to C<< List::MoreUtils >>, C<< Hash::MoreUtils >>
contains trivial but commonly-used functionality for hashes.

=head1 FUNCTIONS

=head2 C HASHREF[, LIST]

Returns a hash containing the (key, value) pair for every
key in LIST.

If no C is given, all keys are assumed as C.

=head2 C HASHREF[, LIST]

As C, but only includes keys whose values are
defined.

If no C is given, all keys are assumed as C.

=head2 C HASHREF[, LIST]

As C but only includes keys which exist in the
hashref.

If no C is given, all keys are assumed as C.

=head2 C BLOCK, HASHREF[, LIST]

As C, with an arbitrary condition.

If no C is given, all keys are assumed as C.

Unlike C, the condition is not given aliases to
elements of anything.  Instead, C<< %_ >> is set to the
contents of the hashref, to avoid accidentally
auto-vivifying when checking keys or values.  Also,
'uninitialized' warnings are turned off in the enclosing
scope.

=cut

sub slice
{
    my ( $href, @list ) = @_;
    @list and return map { $_ => $href->{$_} } @list;
    %{$href};
}

sub slice_exists
{
    my ( $href, @list ) = @_;
    @list or @list = keys %{$href};
    return map { $_ => $href->{$_} } grep {exists( $href->{$_} ) } @list;
}

sub slice_def
{
    my ( $href, @list ) = @_;
    @list or @list = keys %{$href};
    return map { $_ => $href->{$_} } grep { defined( $href->{$_} ) } @list;
}

sub slice_grep (&@)
{
    my ( $code, $href, @list ) = @_;
    local %_ = %{$href};
    @list or @list = keys %{$href};
    no warnings 'uninitialized';
    return map { ( $_ => $_{$_} ) } grep { $code->($_) } @list;
}

=head2 C HASHREF[, MAP]

Returns a hash containing the (key, value) pair for every
key in C.

If no C is given, all keys of C are assumed mapped to theirself.

=head2 C HASHREF[, MAP]

As C, but only includes keys whose values are
defined.

If no C is given, all keys of C are assumed mapped to theirself.

=head2 C HASHREF[, MAP]

As C but only includes keys which exist in the
hashref.

If no C is given, all keys of C are assumed mapped to theirself.

=head2 C BLOCK, HASHREF[, MAP]

As C, with an arbitrary condition.

If no C is given, all keys of C are assumed mapped to theirself.

Unlike C, the condition is not given aliases to
elements of anything.  Instead, C<< %_ >> is set to the
contents of the hashref, to avoid accidentally
auto-vivifying when checking keys or values.  Also,
'uninitialized' warnings are turned off in the enclosing
scope.

=cut

sub slice_map
{
    my ( $href, %map ) = @_;
    %map and return map { $map{$_} => $href->{$_} } keys %map;
    %{$href};
}

sub slice_exists_map
{
    my ( $href, %map ) = @_;
    %map or return slice_exists($href);
    return map { $map{$_} => $href->{$_} } grep {exists( $href->{$_} ) } keys %map;
}

sub slice_def_map
{
    my ( $href, %map ) = @_;
    %map or return slice_def($href);
    return map { $map{$_} => $href->{$_} } grep { defined( $href->{$_} ) } keys %map;
}

sub slice_grep_map (&@)
{
    my ( $code, $href, %map ) = @_;
    %map or return goto &slice_grep;
    local %_ = %{$href};
    no warnings 'uninitialized';
    return map { ( $map{$_} => $_{$_} ) } grep { $code->($_) } keys %map;
}

=head2 C [BLOCK,] HASHREF

  my @array_of_pairs  = hashsort \%hash;
  my @pairs_by_length = hashsort sub { length($a) <=> length($b) }, \%hash;

Returns the (key, value) pairs of the hash, sorted by some
property of the keys.  By default (if no sort block given), sorts the
keys with C.

I'm not convinced this is useful yet.  If you can think of
some way it could be more so, please let me know.

=cut

sub hashsort
{
    my ( $code, $hash ) = @_;
    my $cmp;
    if ( $hash )
    {
        my $package = caller;
        $cmp = sub {
          no strict 'refs';
          local ${$package.'::a'} = $a;
          local ${$package.'::b'} = $b;
          $code->();
        };
    }
    else
    {
        $hash = $code;
        $cmp = sub { $a cmp $b };
    }
    return map { ( $_ => $hash->{$_} ) } sort { $cmp->() } keys %$hash;
}

=head2 C [BLOCK,] HASHREF

  my %dup_rev = safe_reverse \%hash

  sub croak_dup {
      my ($k, $v, $r) = @_;
      exists( $r->{$v} ) and
        croak "Cannot safe reverse: $v would be mapped to both $k and $r->{$v}";
      $v;
  };
  my %easy_rev = save_reverse \&croak_dup, \%hash

Returns safely reversed hash (value, key pairs of original hash). If no
C<< BLOCK >> is given, following routine will be used:

  sub merge_dup {
      my ($k, $v, $r) = @_;
      return exists( $r->{$v} )
             ? ( ref($r->{$v}) ? [ @{$r->{$v}}, $k ] : [ $r->{$v}, $k ] )
	     : $k;
  };

The C will be called with 3 arguments:

=over 8

=item C

The key from the C<< ( key, value ) >> pair in the original hash

=item C

The value from the C<< ( key, value ) >> pair in the original hash

=item C

Reference to the reversed hash (read-only)

=back

The C is expected to return the value which will used
for the resulting hash.

=cut

sub safe_reverse
{
    my ( $code, $hash ) = @_;
    unless ($hash)
    {
        $hash = $code;
        $code = sub {
	      my ($k, $v, $r) = @_;
	      return exists( $r->{$v} )
		     ? ( ref($r->{$v}) ? [ @{$r->{$v}}, $k ] : [ $r->{$v}, $k ] )
		     : $k;
	};
    }

    my %reverse;
    while( my ( $key, $val ) = each %{$hash} )
    {
	$reverse{$val} = &{$code}( $key, $val, \%reverse );
    }
    return %reverse;
}

1;

=head1 AUTHOR

Hans Dieter Pearcey, C<<  >>,
Jens Rehsack, C<<  >>

=head1 BUGS

Please report any bugs or feature requests to
C, or through the web interface at
L.
I will be notified, and then you'll automatically be notified of progress on
your bug as I make changes.

=head1 SUPPORT

You can find documentation for this module with the perldoc command.

    perldoc Hash::MoreUtils

You can also look for information at:

=over 4

=item * RT: CPAN's request tracker

L

=item * AnnoCPAN: Annotated CPAN documentation

L

=item * CPAN Ratings

L

=item * Search CPAN

L

=back

=head1 ACKNOWLEDGEMENTS

=head1 COPYRIGHT & LICENSE

Copyright 2005 Hans Dieter Pearcey, all rights reserved.
Copyright 2010-2013 Jens Rehsack

This program is free software; you can redistribute it and/or modify it
under the terms of either: the GNU General Public License as published
by the Free Software Foundation; or the Artistic License.

See http://dev.perl.org/licenses/ for more information.

=cut

1;    # End of Hash::MoreUtils