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Jens Rehsack > Hash-MoreUtils > Hash::MoreUtils

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Module Version: 0.06   Source  

NAME ^

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

SYNOPSIS ^

  use Hash::MoreUtils qw(:all);
  
  my %h = (foo => "bar", FOO => "BAR", true => 1, false => 0);
  my %s = slice \%h, qw(true false); # (true => 1, false => 0)
  my %f = slice_false \%h; # (false => 0)
  my %u = slice_grep { $_ =~ m/^[A-Z]/ }, \%h; # (FOO => "BAR")
  
  my %r = safe_reverse \%h; # (bar => "foo", BAR => "FOO", 0 => "false", 1 => "true")

DESCRIPTION ^

Similar to List::MoreUtils, Hash::MoreUtils contains trivial but commonly-used functionality for hashes. The primary focus for the moment is providing a common API - speeding up by XS is far away at the moment.

FUNCTIONS ^

slice HASHREF[, LIST]

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

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

slice_def HASHREF[, LIST]

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

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

slice_exists HASHREF[, LIST]

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

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

slice_without HASHREF[, LIST ]

As slice but without any (key/value) pair whose key is in LIST.

If no LIST is given, in opposite to slice an empty list is assumed, thus nothing will be deleted.

slice_missing HASHREF[, LIST]

Returns a HASH containing the (key => undef) pair for every LIST element (as key) that does not exist hashref.

If no LIST is given there are obviously no non-existent keys in HASHREF so the returned HASH is empty.

slice_notdef HASHREF[, LIST]

Searches for undefined slices with the given LIST elements as keys in the given HASHREF. Returns a HASHREF containing the slices (key -> undef) for every undefined item.

To search for undefined slices slice_notdef needs a LIST with items to search for (as keys). If no LIST is given it returns an empty HASHREF even when the given HASHREF contains undefined slices.

slice_true HASHREF[, LIST]

A special slice_grep which returns only those elements of the hash which's values evaluates to TRUE.

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

slice_false HASHREF[, LIST]

A special slice_grep which returns only those elements of the hash which's values evaluates to FALSE.

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

slice_grep BLOCK, HASHREF[, LIST]

As slice, with an arbitrary condition.

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

Unlike grep, the condition is not given aliases to elements of anything. Instead, %_ 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.

slice_map HASHREF[, MAP]

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

If no MAP is given, all keys of HASHREF are assumed mapped to themselves.

slice_def_map HASHREF[, MAP]

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

If no MAP is given, all keys of HASHREF are assumed mapped to themselves.

slice_exists_map HASHREF[, MAP]

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

If no MAP is given, all keys of HASHREF are assumed mapped to themselves.

slice_missing_map HASHREF[, MAP]

As slice_missing but checks for missing keys (of MAP) and map to the value (of MAP) as key in the returned HASH. The slices of the returned HASHREF are always undefined.

If no MAP is given, slice_missing will be used on HASHREF which will return an empty HASH.

slice_notdef_map HASHREF[, MAP]

As slice_notdef but checks for undefined keys (of MAP) and map to the value (of MAP) as key in the returned HASH.

If no MAP is given, slice_notdef will be used on HASHREF which will return an empty HASH.

slice_true_map HASHREF[, MAP]

As slice_map, but only includes pairs whose values are TRUE.

If no MAP is given, all keys of HASHREF are assumed mapped to themselves.

slice_false_map HASHREF[, MAP]

As slice_map, but only includes pairs whose values are FALSE.

If no MAP is given, all keys of HASHREF are assumed mapped to themselves.

slice_grep_map BLOCK, HASHREF[, MAP]

As slice_map, with an arbitrary condition.

If no MAP is given, all keys of HASHREF are assumed mapped to themselves.

Unlike grep, the condition is not given aliases to elements of anything. Instead, %_ 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.

hashsort [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 cmp.

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

safe_reverse [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 = safe_reverse \&croak_dup, \%hash

Returns safely reversed hash (value, key pairs of original hash). If no 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 BLOCK will be called with 3 arguments:

key

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

value

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

ref-hash

Reference to the reversed hash (read-only)

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

AUTHOR ^

Hans Dieter Pearcey, <hdp@cpan.org>, Jens Rehsack, <rehsack@cpan.org>

BUGS ^

Please report any bugs or feature requests to bug-hash-moreutils@rt.cpan.org, or through the web interface at http://rt.cpan.org/NoAuth/ReportBug.html?Queue=Hash-MoreUtils. I will be notified, and then you'll automatically be notified of progress on your bug as I make changes.

SUPPORT ^

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

    perldoc Hash::MoreUtils

You can also look for information at:

ACKNOWLEDGEMENTS ^

COPYRIGHT & LICENSE ^

Copyright 2005 Hans Dieter Pearcey, all rights reserved. Copyright 2010-2018 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.

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