iterator_to_array
(PHP 5 >= 5.1.3)
iterator_to_array — Copy the iterator into an array
Описание
array iterator_to_array
( IteratorAggregate $iterator
[, bool $use_keys
] )
Внимание
К настоящему времени эта функция еще не была документирована; для ознакомления доступен только список аргументов.
Count the elements in an iterator.
Список параметров
- iterator
-
The iterator being counted.
- use_keys
-
Возвращаемые значения
The number of elements in iterator .
Коментарии
The use_keys parameter was added in one of the 5.2.x releases; it defaults to TRUE. This matches the behavior in PHP 5.1.6, which lacks this parameter.Using the boolean param :
<?php
$first = new ArrayIterator( array('k1' => 'a' , 'k2' => 'b', 'k3' => 'c', 'k4' => 'd') );
$second = new ArrayIterator( array( 'k1' => 'X', 'k2' => 'Y', 'Z' ) );
$combinedIterator= new AppendIterator();
$combinedIterator->append( $first );
$combinedIterator->append( $second );
var_dump( iterator_to_array($combinedIterator, false) );
?>
will output :
array(7) (
[0]=>
string(1) "a"
[1]=>
string(1) "b"
[2]=>
string(1) "c"
[3]=>
string(1) "d"
[4]=>
string(1) "X"
[5]=>
string(1) "Y"
[6]=>
string(1) "Z"
)
<?php
var_dump( iterator_to_array($combinedIterator, true) );
?>
will output (since keys would merge) :
array(5) (
["k1"]=>
string(1) "X"
["k2"]=>
string(1) "Y"
["k3"]=>
string(1) "c"
["k4"]=>
string(1) "d"
[0]=>
string(1) "Z"
)
To generate an deep array from nested iterators:
<?php
function iterator_to_array_deep(\Traversable $iterator, $use_keys = true) {
$array = array();
foreach ($iterator as $key => $value) {
if ($value instanceof \Iterator) {
$value = iterator_to_array_deep($value, $use_keys);
}
if ($use_keys) {
$array[$key] = $value;
} else {
$array[] = $value;
}
}
return $array;
}
?>
I use it to test an iterator: https://gist.github.com/jm42/cb328106f393eeb28751
When using iterator_to_array() on an SplObjectStorage object, it's advisable to set $use_keys to false.
The resulting array is identical, since the iterator keys produced by SplObjectStorage::key() are always integers from 0 to (COUNT-1). Passing $use_keys=false cuts out the unnecessary calls to SplObjectStorage::key(), giving a slight performance advantage.
Generator approach
function scandir_deep($dir)
{
foreach (scandir($dir) as $key => $value)
if (in_array($value, [".",".."]))
continue;
else if (is_dir($dir . DIRECTORY_SEPARATOR . $value))
yield $value => scandir_deep($dir . DIRECTORY_SEPARATOR . $value);
else
yield $value;
}
One important thing to remember is that in iterator can be infinite. Not all iterators necessarily end. If iterator_to_array is used on such an iterator, it will exhaust the available memory, and throw a fatal error.
For example, consider the following code:
<?php
function fibonacci(): Generator
{
yield $a = 1;
yield $b = 2;
start:
yield $c = $a + $b;
$a = $b;
$b = $c;
goto start;
}
$fibonacciSequence = fibonacci();
iterator_to_array($fibonacciSequence);
?>
Since <?php fibonacci(); ?> generates an infinite fibonacci sequence, which is valid, since it is actually an infinite sequence, then attempting to convert it to an array will fail.