Online PHP editor | refs for 04Udl

<?php use \ArrayIterator; use \Traversable; class Enumerable { /** * * @var Traversable */ private $traversable; /** * * @param Traversable|array $traversable * @return Enumerable */ public static function enumerate($traversable) { return new Enumerable($traversable); } /** * * @param Traversable|array $traversable */ public function __construct($traversable) { if ($traversable instanceof Traversable) { $this->traversable = $traversable; } else { $this->traversable = new ArrayIterator((array) $traversable); } } /** * * @param callable $callable * @return Enumerable */ public function select(callable $callable) { $generator = function () use ($callable) { foreach ($this->traversable as $key => $value) { yield $key => $callable($value, $key); } }; return new Enumerable($generator()); } /** * * @param callable $callable * @return Enumerable */ public function filter(callable $callable) { $generator = function () use ($callable) { foreach ($this->traversable as $key => $value) { if ($callable($value, $key)) { yield $key => $value; } } }; return new Enumerable($generator()); } /** * * @return array */ public function toArray() { return iterator_to_array($this->traversable); } } $array = Enumerable::enumerate([ 1, 6, 3, 8, 6, 1, 9, 4, 2, 4, 6, 4, 2, ])->select(function ($i) { echo sprintf('Selecting %d * 2', $i) . PHP_EOL; return $i * 2; })->filter(function ($i) { echo sprintf(' Filtering %d > 10', $i) . PHP_EOL; return $i > 10; })->select(function ($i) { echo sprintf(' Selecting %d * 3', $i) . PHP_EOL; return $i * 3; })->filter(function ($i) { echo sprintf(' Filtering %d > 40', $i) . PHP_EOL; return $i > 40; })->select(function ($i) { echo sprintf(' Selecting %d * 4', $i) . PHP_EOL; return $i * 3; })->toArray(); var_dump($array);