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 aboveLike "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(@_) }SEE ALSO
List::Objects::WithUtils::Hash
List::Objects::WithUtils::Hash::Immutable
List::Objects::WithUtils::Hash::Typed
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.