bool interface_exists ( string $interface_name [, bool $autoload = true ] )
http://php.net/manual/en/function.interface-exists.php
array get_declared_interfaces ( void )
<?php
/**
*Array
* (
* [0] => Traversable
* [1] => IteratorAggregate
* [2] => Iterator
* [3] => ArrayAccess
* [4] => reflector
* [5] => RecursiveIterator
* [6] => SeekableIterator
* )
*/
print_r(get_declared_interfaces());
?>
http://php.net/manual/en/function.get-declared-interfaces.php
array class_implements ( mixed $class [, bool $autoload = true ] )
http://php.net/manual/en/function.class-implements.php