ConstMap::filterWithKey

Returns a ConstMap containing the values of the current ConstMap that meet a supplied condition applied to its keys and values.

Description

public function filterWithKey(
  (function(Tk,Tv):bool) $fn,
): ConstMap<Tk,Tv>

Returns a ConstMap containing the values of the current ConstMap that meet a supplied condition applied to its keys and values.

Only keys and values that meet a certain criteria are affected by a call to filterWithKey(), while all values are affected by a call to mapWithKey().

The keys associated with the current ConstMap remain unchanged in the returned ConstMap; the keys will be used in the filtering process only.

Parameters

  • (function(Tk,Tv):bool) $fn - The callback containing the condition to apply to the current ConstMap keys and values.

Return Values