How do you validate if a property is accessible in php?

With classes containing private properties the property_exists() function returns true (php>5.3). With functions there is a method of is_callable that confirms not only the method exists but it is also available (as an alternative to method_exists()). Is there an equivalent counterpart to this function that will confirm if this property is accessible?

<?php

class testClass {

    private $locked;

    public $unlocked;

    private function hiddenFunction(){
        return "hidden";
    }

    public function visibleFunction(){
        return "visible";
    }

}

$object = new testClass();

var_dump(property_exists($object, "unlocked")); // returns true
var_dump(property_exists($object, "locked")); // returns true > php 5.3

var_dump(method_exists($object, "hiddenFunction")); // returns true but can't be called
var_dump(method_exists($object, "visibleFunction")); // returns true

var_dump(is_callable(array($object, "hiddenFunction"))); // returns false
var_dump(is_callable(array($object, "visibleFunction"))); // returns true

?>