Hash::MoreUtils

Section: User Contributed Perl Documentation (3pm)
Updated: 2022-12-06
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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.

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:

•: RT: CPAN's request tracker
<http://rt.cpan.org/NoAuth/Bugs.html?Dist=Hash-MoreUtils>
•: AnnoCPAN: Annotated CPAN documentation
<http://annocpan.org/dist/Hash-MoreUtils>
•: CPAN Ratings
<http://cpanratings.perl.org/d/Hash-MoreUtils>
•: Search CPAN
<http://search.cpan.org/dist/Hash-MoreUtils/>

ACKNOWLEDGEMENTS

COPYRIGHT & LICENSE

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.

Index

slice HASHREF[, LIST]
slice_def HASHREF[, LIST]
slice_exists HASHREF[, LIST]
slice_without HASHREF[, LIST ]
slice_missing HASHREF[, LIST]
slice_notdef HASHREF[, LIST]
slice_true HASHREF[, LIST]
slice_false HASHREF[, LIST]
slice_grep BLOCK, HASHREF[, LIST]
slice_map HASHREF[, MAP]
slice_def_map HASHREF[, MAP]
slice_exists_map HASHREF[, MAP]
slice_missing_map HASHREF[, MAP]
slice_notdef_map HASHREF[, MAP]
slice_true_map HASHREF[, MAP]
slice_false_map HASHREF[, MAP]
slice_grep_map BLOCK, HASHREF[, MAP]
hashsort [BLOCK,] HASHREF
safe_reverse [BLOCK,] HASHREF

COPYRIGHT & LICENSE

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Time: 00:31:13 GMT, April 27, 2024