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DocumentationHSLReferenceFunctionHH\Lib\Keyset\filter_with_key

HH\Lib\Keyset\filter_with_key

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This is available as Keyset\filter_with_key in the www repository.

Returns a new keyset containing only the values for which the given predicate returns true

namespace HH\Lib\Keyset;

function filter_with_key<Tk, Tv as arraykey>(
  KeyedTraversable<Tk, Tv> $traversable,
  (function(Tk, Tv): bool) $predicate,
): keyset<Tv>;

If you don't need access to the key, see Keyset\filter().

Time complexity: O(n * p), where p is the complexity of $predicate Space complexity: O(n)

Parameters

Returns

  • keyset<Tv>

Examples

$result = Keyset\filter_with_key(dict[1 => 2, 2 => 4, 3 => 5], ($key, $val) ==> $val%2==0);
print_r($result);
//result: keyset[2,4]

$result = Keyset\filter_with_key(dict[1 => 2, 2 => 4], ($key, $val) ==> $val==0);
print_r($result);
//result: keyset[]

$result = Keyset\filter_with_key(dict[1 => 2, 2 => 4, 3 => 5],  ($key, $val) ==> $val == $val);
print_r($result);
//result: keyset[2,4,5]