ResourceStorage.class.php

<?php
// modeled after SplObjectStorage
// license: WTFPL, The Unlicense, CC0, whatever
/*
example usage:
$r1=tmpfile();
$r2=tmpfile();
$rs=new ResourceStorage();
$rs[$r1]='foo';
$rs->attach($r2,'bar');
foreach($rs as $foo){
    var_dump($foo);
}
var_dump($rs);
unset($rs[$r1]);
var_dump($rs,isset($rs[$r1]),isset($rs[$r2]));
$rs->detach($r2);
var_dump($rs);
*/


class ResourceStorage implements ArrayAccess, Countable, IteratorAggregate {
	protected $data = [ ];
	public function count() {
		return count ( $this->data );
	}
	public function getIterator() {
		return new ArrayIterator ( $this->data );
	}
	public function offsetSet($resource, $data) {
		if (! is_resource ( $resource )) {
			throw new \UnexpectedValueException ( 'expected resource, got ' . static::return_var_dump ( $resource ) );
		} else {
			$this->data [( int ) $resource] = $data;
		}
	}
	public function offsetExists($resource): bool {
		return array_key_exists ( ( int ) $resource, $this->data );
	}
	public function offsetUnset($resource) {
		unset ( $this->data [$resource] );
	}
	public function offsetGet($resource) {
		return array_key_exists ( ( int ) $resource, $this->data ) ? $this->data [( int ) $resource] : null;
	}
	function attach($resource, $data) {
		if (! is_resource ( $resource )) {
			throw new \InvalidArgumentException ();
		}
		$this->offsetSet ( $resource, $data );
		return;
	}
	function detach($resource) {
		if (! is_resource ( $resource )) {
			throw new \InvalidArgumentException ();
		}
		$this->offsetUnset ( $resource );
		return;
	}
	protected static function return_var_dump(): string {
		$args = func_get_args ();
		ob_start ();
		call_user_func_array ( 'var_dump', $args );
		return ob_get_clean ();
	}
}