PHP 5.6.18 is available

The IteratorIterator class

(PHP 5 >= 5.1.0, PHP 7)

Einführung

This iterator wrapper allows the conversion of anything that is Traversable into an Iterator. It is important to understand that most classes that do not implement Iterators have reasons as most likely they do not allow the full Iterator feature set. If so, techniques should be provided to prevent misuse, otherwise expect exceptions or fatal errors.

Klassenbeschreibung

IteratorIterator implements OuterIterator {
/* Methoden */
public __construct ( Traversable $iterator )
public mixed current ( void )
public Traversable getInnerIterator ( void )
public scalar key ( void )
public void next ( void )
public void rewind ( void )
public bool valid ( void )
}

Anmerkungen

Hinweis:

This class permits access to methods of the inner iterator via the __call magic method.

Inhaltsverzeichnis

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User Contributed Notes 2 notes

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6
sven at rtbg dot de
9 months ago
This iterator basically is only a wrapper around another iterator. It does nothing fancy, it simply forwards any calls of rewind(), next(), valid(), current() and key() to the inner iterator. This inner iterator can be fetched with getInnerIterator().

One special case: When passing an IteratorAggregate object, the getIterator() method of that object will be called and THAT iterator will be iterated over, and this will also be returned when calling getInnerIterator().

This class can be extended, so it's an ideal building block for your own classes that only want to modify one or two of the iterator methods, but not all.

Want to trim the strings returned by the current() method?

<?php

class TrimIterator extends IteratorIterator
{
    public function
current() {
        return
trim(parent::current());
    }
}

$innerIterator = new ArrayIterator(array('normal', ' trimmable '));

$trim = new TrimIterator($innerIterator);

foreach (
$trim as $key => $value) {
    echo
"Key:\n";
   
var_dump($key);
    echo
"Value:\n";
   
var_dump($value);
    echo
"---next---";
}
?>

Output:

Key:
int(0)
Value:
string(6) "normal"
---next---Key:
int(1)
Value:
string(9) "trimmable"
---next---
up
1
wallacemaxters at gmail dot lcom
26 days ago
Another example of the efficiency for IteratorIterator is a small class for enumerate for iterations of an interator implementation.

Example:

<?php

class Enumerator extends IteratorIterator
{   
   
/**
    * Initial value for enumerator
    * @param int 
    */
   
protected $start = 0;

   
/**
    * @param int
    */
   
protected $key = 0;

   
/**
    * @param Traversable $iterator
    * @param scalar $start
    */
   
public function __construct(Traversable $iterator, $start = 0)
    {
       
parent::__construct($iterator);

       
$this->start = $start;

       
$this->key = $this->start;
    }

    public function
key()var_dump
   
{
        return
$this->key;
    }

    public function
next()
    {
        ++
$this->key;

       
parent::next();
    }

    public function
rewind()
    {
       
$this->key = $this->start;

       
parent::rewind();
    }

}
?>

This produces:

<?php

$enumerator
= new Enumerator(
       new
ArrayIterator(['php', 'java', 'python']); 7000
);

print_r(iterator_to_array($enumerator));

/*
*    array(3) {
           7000 => 'php',
           7001 => 'java',
           7002 => 'python'
     }
*/

?>
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