NAME

List::Objects::WithUtils::Role::Hash - Hash manipulation methods

SYNOPSIS


            
              
              ## Via List::Objects::WithUtils::Hash ->
use List::Objects::WithUtils 'hash';
my $hash = hash(foo => 'bar');
$hash->set(
  foo => 'baz',
  pie => 'tasty',
);
my @matches = $hash->keys->grep(sub { $_[0] =~ /foo/ })->all;
my $pie = $hash->get('pie')
  if $hash->exists('pie');
for my $pair ( $hash->kv->all ) {
  my ($key, $val) = @$pair;
  ...
}
my $obj = $hash->inflate;
my $foo = $obj->foo;
## As a Role ->
use Role::Tiny::With;
with 'List::Objects::WithUtils::Role::Hash';

DESCRIPTION

A Role::Tiny role defining methods for creating and manipulating HASH-type objects.

In addition to the methods documented below, these objects provide a TO_JSON method exporting a plain HASH-type reference for convenience when feeding JSON::Tiny or similar, as well as a TO_ZPL method for compatibility with Text::ZPL.

Basic hash methods

new

Constructs a new HASH-type object.

copy

Creates a shallow clone of the current object.

defined


            
              
              if ( $hash->defined($key) ) { ... }

Returns boolean true if the key has a defined value.

exists


            
              
              if ( $hash->exists($key) ) { ... }

Returns boolean true if the key exists.

export


            
              
              my %hash = $hash->export;

Returns a raw key => value list.

For a plain HASH-type reference, see: "unbless"

array_type

The class name of array-type objects that will be used to contain the results of methods returning a list.

Defaults to List::Objects::WithUtils::Array.

Subclasses can override array_type to produce different types of array objects.

inflate


            
              
              my $obj = hash(foo => 'bar', baz => 'quux')->inflate;
my $baz = $obj->baz;

Inflates the hash-type object into a simple struct-like object with accessor methods matching the keys of the hash.

By default, accessors are read-only; specifying rw = 1> allows setting new values:


            
              
              my $obj = hash(foo => 'bar', baz => 'quux')->inflate(rw => 1);
$obj->foo('frobulate');

Returns an "inflated_type" (or "inflated_rw_type") object.

The default objects provide a DEFLATE method returning a plain hash; this makes it easy to turn inflated objects back into a hash() for modification:


            
              
              my $first = hash( foo => 'bar', baz => 'quux' )->inflate;
my $second = hash( $first->DEFLATE, frobulate => 1 )->inflate;

inflated_type

The class that objects are blessed into when calling "inflate".

Defaults to List::Objects::WithUtils::Hash::Inflated.

inflated_rw_type

The class that objects are blessed into when calling "inflate" with rw = 1> specified.

Defaults to List::Objects::WithUtils::Hash::Inflated::RW, a subclass of List::Objects::WithUtils::Hash::Inflated.

is_empty

Returns boolean true if the hash has no keys.

is_mutable

Returns boolean true if the hash is mutable; immutable subclasses can override to provide a negative value.

is_immutable

The opposite of "is_mutable".

unbless

Returns a plain HASH reference (shallow clone).

Methods that manipulate the hash

clear

Clears the current hash entirely.

Returns the (same, but now empty) hash object.

delete


            
              
              $hash->delete(@keys);

Deletes the given key(s) from the hash.

Returns an "array_type" object containing the deleted values.

set


            
              
              $hash->set(
  key1 => $val,
  key2 => $other,
)

Sets keys in the hash.

Returns the current hash object.

maybe_set


            
              
              my $hash = hash(foo => 1, bar => 2, baz => 3);
$hash->maybe_set(foo => 2, bar => 3, quux => 4);
# $hash = +{ foo => 1, bar => 2, baz => 3, quux => 4 }

Like "set", but only sets values that do not already exist in the hash.

Returns the current hash object.

Methods that retrieve items

get


            
              
              my $val  = $hash->get($key);
my @vals = $hash->get(@keys)->all;

Retrieves a key or list of keys from the hash.

If taking a slice (multiple keys were specified), values are returned as an "array_type" object. (See "sliced" if you'd rather generate a new hash.)

get_path


            
              
              my $hash = hash(
  foo  => +{ bar => +{ baz => 'bork'  } },
  quux => [ +{ weeble => 'snork' } ],
);
my $item = $hash->get_path(qw/foo bar baz/);  # 'bork'

Attempt to retrieve a value from a 'deep' hash (without risking autovivification).

If an element of the given path is a (plain) array reference, as in this example:


            
              
              my $item = $hash->get_path('quux', [1], 'weeble');  # "snork"

... then it is taken as the index of an array or array-type object in the path.

Returns undef if any of the path elements are nonexistant.

An exception is thrown if an invalid access is attempted, such as trying to use a hash-type object as if it were an array.

(Available from v2.15.1)

get_or_else


            
              
              # Expect to find an array() obj at $key in $hash,
# or create an empty one if $key doesn't exist:
my @all = $hash->get_or_else($key => array)->all;
# Or pass a coderef
# First arg is the object being operated on
# Second arg is the requested key
my $item = $hash->get_or_else($key => sub { shift->get($defaultkey) });

Retrieves a key from the hash; optionally takes a second argument that is used as a default value if the given key does not exist in the hash.

If the second argument is a coderef, it is invoked on the object (with the requested key as an argument) and its return value is taken as the default value.

keys


            
              
              my @keys = $hash->keys->all;

Returns the list of keys in the hash as an "array_type" object.

values


            
              
              my @vals = $hash->values->all;

Returns the list of values in the hash as an "array_type" object.

inverted


            
              
              my $hash = hash(
  a => 1,
  b => 2,
  c => 2,
  d => 3
);
my $newhash = $hash->inverted;
# $newhash = +{
#   1 => array('a'),
#   2 => array('b', 'c'),
#   3 => array('d'),
# }

Inverts the hash; the values of the original hash become keys in the new object. Their corresponding values are "array_type" objects containing the key(s) that mapped to the original value.

This is a bit like reversing the hash, but lossless with regards to non-unique values.

(Available from v2.14.1)

iter


            
              
              my $iter = $hash->iter;
while (my ($key, $val) = $iter->()) {
  # ...
}

Returns an iterator that, when called, returns ($key, $value) pairs. When the list is exhausted, an empty list is returned.

The iterator operates on a shallow clone of the hash, making it safe to operate on the original hash while using the iterator.

(Available from v2.9.1)

kv


            
              
              for my $pair ($hash->kv->all) {
  my ($key, $val) = @$pair;
}

Returns an "array_type" object containing the key/value pairs in the hash, each of which is a two-element (unblessed) ARRAY.

kv_grep


            
              
              my $positive_vals = $hash->kv_grep(sub { $b > 0 });

Like grep, but operates on pairs. See "pairgrep" in List::Util.

Returns a hash-type object consisting of the key/value pairs for which the given block returned true.

(Available from v2.21.1)

kv_map


            
              
              # Add 1 to each value, get back an array-type object:
my $kvs = hash(a => 2, b => 2, c => 3)
  ->kv_map(sub { ($a, $b + 1) });

Like map, but operates on pairs. See "pairmap" in List::Util.

Returns an "array_type" object containing the results of the map.

(Available from v2.8.1; in versions prior to v2.20.1, $_[0] and $_[1] must be used in place of $a and $b, respectively.)

kv_sort


            
              
              my $kvs = hash(a => 1, b => 2, c => 3)->kv_sort;
# $kvs = array(
#          [ a => 1 ], 
#          [ b => 2 ], 
#          [ c => 3 ]
#        )
my $reversed = hash(a => 1, b => 2, c => 3)
  ->kv_sort(sub { $b cmp $a });
# Reverse result as above

Like "kv", but sorted by key. A sort routine can be provided.

In versions prior to v2.19.1, $_[0] and $_[1] must be used in place of $a and $b, respectively.

random_kv

Returns a random key/value pair from the hash as an ARRAY-type reference.

Returns undef if the hash is empty.

(Available from v2.28.1)

random_key

Returns a random key from the hash.

Returns undef if the hash is empty.

(Available from v2.28.1)

random_value

Returns a random value from the hash.

Returns undef if the hash is empty.

(Available from v2.28.1)

sliced


            
              
              my $newhash = $hash->sliced(@keys);

Returns a new hash object built from the specified set of keys and their respective values.

If a given key is not found in the hash, it is omitted from the result (this is different than perl-5.20+ hash slice syntax, which sets unknown keys to undef in the slice).

If you only need the values, see "get".

Methods that compare hashes

intersection


            
              
              my $first  = hash(a => 1, b => 2, c => 3);
my $second = hash(b => 2, c => 3, d => 4);
my $intersection = $first->intersection($second);
my @common = $intersection->sort->all;

Returns the list of keys common between all given hash-type objects (including the invocant) as an "array_type" object.

diff

The opposite of "intersection"; returns the list of keys that are not common to all given hash-type objects (including the invocant) as an "array_type" object.

NOTES FOR CONSUMERS

If creating your own consumer of this role, some extra effort is required to make $a and $b work in sort statements without warnings; an example with a custom exported constructor might look something like:


            
              
              package My::Custom::Hash;
use strictures 2;
require Role::Tiny;
Role::Tiny->apply_roles_to_package( __PACKAGE__,
  qw/
    List::Objects::WithUtils::Role::Hash
    My::Custom::Hash::Role
  /
);
use Exporter ();
our @EXPORT = 'myhash';
sub import {
  my $pkg = caller;
  { no strict 'refs';
    ${"${pkg}::a"} = ${"${pkg}::a"};
    ${"${pkg}::b"} = ${"${pkg}::b"};
  }
  goto &Exporter::import
}
sub myhash { __PACKAGE__->new(@_) }

AUTHOR

Jon Portnoy <avenj@cobaltirc.org>

Portions of this code are derived from Data::Perl by Matthew Phillips (CPAN: MATTP), haarg et al

Licensed under the same terms as Perl.

To install List::Objects::WithUtils, copy and paste the appropriate command in to your terminal.

cpanm

cpanm List::Objects::WithUtils

CPAN shell

perl -MCPAN -e shell
install List::Objects::WithUtils

For more information on module installation, please visit the detailed CPAN module installation guide.

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NAME

SYNOPSIS

DESCRIPTION

Basic hash methods

new

copy

defined

exists

export

array_type

inflate

inflated_type

inflated_rw_type

is_empty

is_mutable

is_immutable

unbless

Methods that manipulate the hash

clear

delete

set

maybe_set

Methods that retrieve items

get

get_path

get_or_else

keys

values

inverted

iter

kv

kv_grep

kv_map

kv_sort

random_kv

random_key

random_value

sliced

Methods that compare hashes

intersection

diff

NOTES FOR CONSUMERS

SEE ALSO

AUTHOR

Module Install Instructions