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<?php
/**
* Zend Framework (http://framework.zend.com/)
*
* @link http://github.com/zendframework/zf2 for the canonical source repository
* @copyright Copyright (c) 2005-2015 Zend Technologies USA Inc. (http://www.zend.com)
* @license http://framework.zend.com/license/new-bsd New BSD License
*/
namespace Zend\Stdlib;
use ReflectionClass;
/**
* CallbackHandler
*
* A handler for an event, event, filterchain, etc. Abstracts PHP callbacks,
* primarily to allow for lazy-loading and ensuring availability of default
* arguments (currying).
*/
class CallbackHandler
{
/**
* @var string|array|callable PHP callback to invoke
*/
protected $callback;
/**
* Callback metadata, if any
* @var array
*/
protected $metadata;
/**
* PHP version is greater as 5.4rc1?
* @var bool
*/
protected static $isPhp54;
/**
* Constructor
*
* @param string|array|object|callable $callback PHP callback
* @param array $metadata Callback metadata
*/
public function __construct($callback, array $metadata = array())
{
$this->metadata = $metadata;
$this->registerCallback($callback);
}
/**
* Registers the callback provided in the constructor
*
* @param callable $callback
* @throws Exception\InvalidCallbackException
* @return void
*/
protected function registerCallback($callback)
{
if (!is_callable($callback)) {
throw new Exception\InvalidCallbackException('Invalid callback provided; not callable');
}
$this->callback = $callback;
}
/**
* Retrieve registered callback
*
* @return callable
*/
public function getCallback()
{
return $this->callback;
}
/**
* Invoke handler
*
* @param array $args Arguments to pass to callback
* @return mixed
*/
public function call(array $args = array())
{
$callback = $this->getCallback();
// Minor performance tweak, if the callback gets called more than once
if (!isset(static::$isPhp54)) {
static::$isPhp54 = version_compare(PHP_VERSION, '5.4.0rc1', '>=');
}
$argCount = count($args);
if (static::$isPhp54 && is_string($callback)) {
$result = $this->validateStringCallbackFor54($callback);
if ($result !== true && $argCount <= 3) {
$callback = $result;
// Minor performance tweak, if the callback gets called more
// than once
$this->callback = $result;
}
}
// Minor performance tweak; use call_user_func() until > 3 arguments
// reached
switch ($argCount) {
case 0:
if (static::$isPhp54) {
return $callback();
}
return call_user_func($callback);
case 1:
if (static::$isPhp54) {
return $callback(array_shift($args));
}
return call_user_func($callback, array_shift($args));
case 2:
$arg1 = array_shift($args);
$arg2 = array_shift($args);
if (static::$isPhp54) {
return $callback($arg1, $arg2);
}
return call_user_func($callback, $arg1, $arg2);
case 3:
$arg1 = array_shift($args);
$arg2 = array_shift($args);
$arg3 = array_shift($args);
if (static::$isPhp54) {
return $callback($arg1, $arg2, $arg3);
}
return call_user_func($callback, $arg1, $arg2, $arg3);
default:
return call_user_func_array($callback, $args);
}
}
/**
* Invoke as functor
*
* @return mixed
*/
public function __invoke()
{
return $this->call(func_get_args());
}
/**
* Get all callback metadata
*
* @return array
*/
public function getMetadata()
{
return $this->metadata;
}
/**
* Retrieve a single metadatum
*
* @param string $name
* @return mixed
*/
public function getMetadatum($name)
{
if (array_key_exists($name, $this->metadata)) {
return $this->metadata[$name];
}
return;
}
/**
* Validate a static method call
*
* Validates that a static method call in PHP 5.4 will actually work
*
* @param string $callback
* @return true|array
* @throws Exception\InvalidCallbackException if invalid
*/
protected function validateStringCallbackFor54($callback)
{
if (!strstr($callback, '::')) {
return true;
}
list($class, $method) = explode('::', $callback, 2);
if (!class_exists($class)) {
throw new Exception\InvalidCallbackException(sprintf(
'Static method call "%s" refers to a class that does not exist',
$callback
));
}
$r = new ReflectionClass($class);
if (!$r->hasMethod($method)) {
throw new Exception\InvalidCallbackException(sprintf(
'Static method call "%s" refers to a method that does not exist',
$callback
));
}
$m = $r->getMethod($method);
if (!$m->isStatic()) {
throw new Exception\InvalidCallbackException(sprintf(
'Static method call "%s" refers to a method that is not static',
$callback
));
}
// returning a non boolean value may not be nice for a validate method,
// but that allows the usage of a static string callback without using
// the call_user_func function.
return array($class, $method);
}
}
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