NAME

Data::DeepAccess - Access or set data in deep structures

SYNOPSIS

  use Data::DeepAccess qw(deep_exists deep_get deep_set);

  my %things;
  deep_set(\%things, qw(foo bar), 42);
  say $things{foo}{bar}; # 42

  $things{foo}{baz} = ['a'..'z'];
  say deep_get(\%things, qw(foo baz 5)); # f

  deep_get(\%things, qw(foo baz 26)) = 'AA';
  say $things{foo}{baz}[-1]; # AA

DESCRIPTION

Provides the functions "deep_get" and "deep_set" that traverse nested data structures to retrieve or set the value located by a list of keys.

When traversing, keys are applied according to the type of referenced data structure. A hash will be traversed by hash key, an array by array index, and an object by method call (scalar context with no arguments). If the data structure is not defined, it will be traversed as a hash by default (but not vivified unless in a set operation).

You can override how a key is applied, and thus what type of structure is vivified if necessary, by passing the key in a hashref as the value of key (hash) or index (array).

  deep_set(my $structure, 'foo', 42); # {foo => 42}
  deep_set(my $structure, {index => 1}, 42); # [undef, 42]
  deep_set($object, {key => 'foo'}, 42); # sets $object->{foo} directly

For the rare case it's needed, you can also use one of the keys method or lvalue.

  deep_set($object, {method => 'foo'}, 42); # $object->foo(42)
  deep_set($object, {lvalue => 'foo'}, 42); # $object->foo = 42

Attempting to traverse intermediate structures that are defined and not a reference to a hash, array, or object will result in an exception.

If an object method call is the last key in a set operation or the next structure must be vivified, the method will be called passing the new value as an argument or assigned if it is treated as an lvalue. Attempting to call a method on an undefined value or unblessed ref in a set operation will result in an exception.

Currently, undefined results from non-lvalue method calls are not vivified back to the object to support setting a further nested value. This may be supported in the future.

FUNCTIONS

All functions are exported individually.

deep_exists

  my $bool = deep_exists($structure, @keys);

Returns a true value if the value exists in the referenced structure located by the given keys. No intermediate structures will be altered or vivified; a missing structure will result in a false return value.

Array indexes are tested for existence with "exists" in perlfunc, like hash keys, which may have surprising results in sparse arrays. Avoid this situation.

Object methods are tested for existence with $object->can($method).

If no keys are passed, returns true.

deep_get

  my $value  = deep_get($structure, @keys);

Retrieves the value from the referenced structure located by the given keys. No intermediate structures will be altered or vivified; a missing structure will result in undef.

If no keys are passed, returns the original structure.

deep_set

  $new_value = deep_set($structure, @keys, $new_value);

Sets the value in the referenced structure located by the given keys. Missing intermediate structures will be vivified to hashrefs by default. If the structure is undefined, it must be an assignable lvalue to be vivified.

If no keys are passed, the structure must be an assignable lvalue and will be assigned the value directly.

BUGS

Report any issues on the public bugtracker.

AUTHOR

Dan Book <dbook@cpan.org>

COPYRIGHT AND LICENSE

This software is Copyright (c) 2019 by Dan Book.

This is free software, licensed under:

  The Artistic License 2.0 (GPL Compatible)

SEE ALSO

Hash::DeepAccess, Data::DPath, Data::Deep