The IteratorAggregate interface

(PHP 5, PHP 7, PHP 8)

Introduction

Interface to create an external Iterator.

Interface synopsis

interface IteratorAggregate extends Traversable {
/* Methods */
}

Examples

Example #1 Basic usage

<?php

class myData implements IteratorAggregate
{
public
$property1 = "Public property one";
public
$property2 = "Public property two";
public
$property3 = "Public property three";
public
$property4 = "";

public function
__construct()
{
$this->property4 = "last property";
}

public function
getIterator(): Traversable
{
return new
ArrayIterator($this);
}
}

$obj = new myData();

foreach (
$obj as $key => $value) {
var_dump($key, $value);
echo
"\n";
}

?>

The above example will output something similar to:

string(9) "property1"
string(19) "Public property one"

string(9) "property2"
string(19) "Public property two"

string(9) "property3"
string(21) "Public property three"

string(9) "property4"
string(13) "last property"

Table of Contents

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User Contributed Notes 4 notes

up
29
trumbull dot j at gmail dot com
7 years ago
It might seem obvious, but you can return a compiled generator from your IteratorAggregate::getIterator() implementation.

<?php
class Collection implements IteratorAggregate
{
private
$items = [];

public function
__construct($items = [])
{
$this->items = $items;
}

public function
getIterator()
{
return (function () {
while(list(
$key, $val) = each($this->items)) {
yield
$key => $val;
}
})();
}
}

$data = [ 'A', 'B', 'C', 'D' ];
$collection = new Collection($data);

foreach (
$collection as $key => $val) {
echo
sprintf("[%s] => %s\n", $key, $val);
}
?>
up
22
Tab Atkins
12 years ago
Note that, at least as of 5.3, you still aren't allowed to return a normal Array from getIterator().

In some places, the docs wrap the array into an ArrayObject and return that. DON'T DO IT. ArrayObject drops any empty-string keys on the floor when you iterate over it (again, at least as of 5.3).

Use ArrayIterator instead. I wouldn't be surprised if it didn't have its own set of wonderful bugs, but at the very least it works correctly when you use it with this method.
up
11
Martin Speer
5 years ago
You can use yield from in getIterator in recent PHP 7 versions:

<?php

class Example implements \IteratorAggregate
{
protected
$data = [];

public function
__construct(array $data)
{
$this->data = $data;
}

public function
getIterator()
{
yield from
$this->data;
}
}

$test = new Example([1, 2, 3]);

foreach (
$test as $node) {
echo
$test, PHP_EOL;
}

/*
* Outputs:
*
* 1
* 2
* 3
*/
?>
up
15
Lubaev.K
11 years ago
<?php
// IteratorAggregate
// Create indexed and associative arrays.

class myData implements IteratorAggregate {

private
$array = [];
const
TYPE_INDEXED = 1;
const
TYPE_ASSOCIATIVE = 2;

public function
__construct( array $data, $type = self::TYPE_INDEXED ) {
reset($data);
while( list(
$k, $v) = each($data) ) {
$type == self::TYPE_INDEXED ?
$this->array[] = $v :
$this->array[$k] = $v;
}
}

public function
getIterator() {
return new
ArrayIterator($this->array);
}

}

$obj = new myData(['one'=>'php','javascript','three'=>'c#','java',], /*TYPE 1 or 2*/ );

foreach(
$obj as $key => $value) {
var_dump($key, $value);
echo
PHP_EOL;
}

// if TYPE == 1
#int(0)
#string(3) "php"
#int(1)
#string(10) "javascript"
#int(2)
#string(2) "c#"
#int(3)
#string(4) "java"

// if TYPE == 2
#string(3) "one"
#string(3) "php"
#int(0)
#string(10) "javascript"
#string(5) "three"
#string(2) "c#"
#int(1)
#string(4) "java"
?>

Good luck!
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