(PHP 5 >= 5.4.0, PHP 7, PHP 8)
The callback should accept up to three arguments: the current item, the current key and the iterator, respectively.
Example #1 Available callback arguments
<?php
/**
* Callback for CallbackFilterIterator
*
* @param $current Current item's value
* @param $key Current item's key
* @param $iterator Iterator being filtered
* @return boolean TRUE to accept the current item, FALSE otherwise
*/
function my_callback($current, $key, $iterator) {
// Your filtering code here
}
?>
Any callable may be used; such as a string containing a function name, an array for a method, or an anonymous function.
Example #2 Callback basic examples
<?php
$dir = new FilesystemIterator(__DIR__);
// Filter large files ( > 100MB)
function is_large_file($current) {
return $current->isFile() && $current->getSize() > 104857600;
}
$large_files = new CallbackFilterIterator($dir, 'is_large_file');
// Filter directories
$files = new CallbackFilterIterator($dir, function ($current, $key, $iterator) {
return $current->isDir() && ! $iterator->isDot();
});
?>
CallbackFilterIterator class didnot implement OuterIterator interface directly
below is the correct hierarchy
CallbackFilterIterator
|__FilterIterator
|___ IteratorIterator
|____ OuterIterator
please fix the documentation
i PHP 7 you can use Anonymous classes to get the same results.
<?php
class MyIterator implements Iterator
{
/**
* @var \Iterator
*/
protected $next;
/**
* Collection constructor.
*
* @param \Iterator $next
*/
public function __construct(Iterator $next)
{
$this->next = $next;
}
/**
* @param callable $callback
*
* @return static
*/
public function filter(callable $callback = null)
{
return new static(new class($this, $callback) extends FilterIterator
{
protected $callback;
public function __construct(\Iterator $iterator, callable $callback = null)
{
parent::__construct($iterator);
$this->callback = $callback ?: function($current) {
return ! empty($current);
};;
}
public function accept()
{
return call_user_func($this->callback, parent::accept());
}
});
}
// Iterator methods ...
}
// .......
?>
Implementation for PHP < 5.4:
<?php
if (!class_exists('CallbackFilterIterator')) {
class CallbackFilterIterator extends FilterIterator {
protected $callback;
// "Closure" type hint should be "callable" in PHP 5.4
public function __construct(Iterator $iterator, Closure $callback = null) {
$this->callback = $callback;
parent::__construct($iterator);
}
public function accept() {
return call_user_func(
$this->callback,
$this->current(),
$this->key(),
$this->getInnerIterator()
);
}
}
}
?>