HH\Map::slice

Returns a subset of the current Map starting from a given key location up to, but not including, the element at the provided length from the starting key location

Description

public function slice(
  int $start,
  int $len,
): Map<Tk, Tv>

$start is 0-based. $len is 1-based. So slice(0, 2) would return the keys and values at key location 0 and 1.

The returned Map will always be a proper subset of the current Map.

Parameters

  • $start - The starting key location of the current Map for the returned Map.
  • $len - The length of the returned Map.

Return Values

  • Map<Tk, Tv> - A Map that is a proper subset of the current Map starting at $start up to but not including the element $start + $len.

Examples

<?hh

namespace Hack\UserDocumentation\API\Examples\Map\Slice;

$m = Map {
  'red' => '#ff0000',
  'green' => '#00ff00',
  'blue' => '#0000ff',
  'yellow' => '#ffff00',
  'purple' => '#663399',
};

// Start at key index 1 ('green') and include 3 elements
$m2 = $m->slice(1, 3);

var_dump($m2);
Output
object(HH\Map)#2 (3) {
  ["green"]=>
  string(7) "#00ff00"
  ["blue"]=>
  string(7) "#0000ff"
  ["yellow"]=>
  string(7) "#ffff00"
}