Generators Sample Code

coroutine.php

<?php
class Task {
	protected $taskId;
	protected $coroutine;
	protected $sendValue = null;
	protected $beforeFirstYield = true;

	public function __construct($taskId, Generator $coroutine) {
		$this->taskId = $taskId;
		$this->coroutine = $coroutine;
	}

	public function getTaskId() {
		return $this->taskId;
	}

	public function setSendValue($sendValue) {
		$this->sendValue = $sendValue;
	}

	public function run() {
		if ($this->beforeFirstYield) {
			$this->beforeFirstYield = false;
			return $this->coroutine->current();
		} else {
			$retval = $this->coroutine->send($this->sendValue);
			$this->sendValue = null;
			return $retval;
		}
	}

	public function isFinished() {
		return !$this->coroutine->valid();
	}
}

class Scheduler {
	protected $maxTaskId = 0;
	protected $taskMap = []; // taskId => task
	protected $taskQueue;

	public function __construct() {
		$this->taskQueue = new SplQueue();
	}

	public function newTask(Generator $coroutine) {
		$tid = ++$this->maxTaskId;
		$task = new Task($tid, $coroutine);
		$this->taskMap[$tid] = $task;
		$this->schedule($task);
		return $tid;
	}

	public function schedule(Task $task) {
		$this->taskQueue->enqueue($task);
	}

	public function run() {
		while (!$this->taskQueue->isEmpty()) {
			$task = $this->taskQueue->dequeue();
			echo $task->run();

			if ($task->isFinished()) {
				unset($this->taskMap[$task->getTaskId()]);
			} else {
				$this->schedule($task);
			}
		}
	}
}

function task1() {
	for ($i = 1; $i <= 10; ++$i) {
		echo "This is task 1 iteration $i.\n";
		yield;
	}
}

function task2() {
	for ($i = 1; $i <= 5; ++$i) {
		echo "This is task 2 iteration $i.\n";
		yield;
	}
}

$scheduler = new Scheduler;

$scheduler->newTask(task1());
$scheduler->newTask(task2());

$scheduler->run();

test.php

<?php
function getRangeArray($max = 10) {
	$array = [];

	for ($i = 1; $i < $max; $i++) {
		$array[] = $i;
	}

	return $array;
}

function getRangeGenerator($max = 10) {
	for ($i = 1; $i < $max; $i++) {
		yield $i;
	}
}

class SimpleIterator implements Iterator {
	private $position = 1;
	private $max = 1;

	public function __construct($max = 15) {
		$this->position = 1;
		$this->max = $max;
	}

	function rewind() {
		$this->position = 1;
	}

	function current() {
		return $this->position;
	}

	function key() {
		return $this->position;
	}

	function next() {
		++$this->position;
	}

	function valid() {
		return ($this->position < $this->max);
	}
}

// ---- Toggle each of these in turn. ----

// foreach (getRangeArray(15) as $range) {
// 	echo "Value: {$range} \n";
// }

// foreach (getRangeArray(PHP_INT_MAX) as $range) {
// 	echo "Dataset {$range} \n";
// }

// foreach (getRangeGenerator(15) as $range) {
// 	echo "Dataset {$range} \n";
// }


// foreach ((new SimpleIterator(15)) as $range) {
// 	echo "Value: {$range} \n";
// }

// foreach ((getRangeGenerator(PHP_INT_MAX)) as $range) {
// 	echo "Dataset {$range} \n";
// }

foreach ((new SimpleIterator(PHP_INT_MAX)) as $range) {
	echo "Value: {$range} \n";
}