silverstripe-fulltextsearch/code/utils/CombinationsArrayIterator.php

<?php

class CombinationsArrayIterator implements Iterator {
	protected $arrays;
	protected $keys;
	protected $numArrays;

	protected $isValid = false;
	protected $k = 0;

	function __construct($args) {
		$this->arrays = array();
		$this->keys = array();

		$keys = array_keys($args);
		$values = array_values($args);

		foreach ($values as $i => $arg) {
			if (is_array($arg) && count($arg)) {
				$this->arrays[] = $arg;
				$this->keys[] = $keys[$i];
			}
		}

		$this->numArrays = count($this->arrays);
		$this->rewind();
	}

	function rewind() {
		if (!$this->numArrays) {
			$this->isValid = false;
		}
		else {
			$this->isValid = true;
			$this->k = 0;
			
			for ($i = 0; $i < $this->numArrays; $i++) reset($this->arrays[$i]);
		}
	}

	function valid() {
		return $this->isValid;
	}

	function next() {
		$this->k++;

		for ($i = 0; $i < $this->numArrays; $i++) {
			if (next($this->arrays[$i]) === false) {
				if ($i == $this->numArrays-1) $this->isValid = false;
				else reset($this->arrays[$i]);
			}
			else break;
		}
	}

	function current() {
		$res = array();
		for ($i = 0; $i < $this->numArrays; $i++) $res[$this->keys[$i]] = current($this->arrays[$i]);
		return $res;
	}

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