The MultipleIterator class

(PHP 5 >= 5.3.0)

Introduction

An Iterator that sequentially iterates over all attached iterators

Class synopsis

MultipleIterator implements Iterator {

/* Constants */

const integer MIT_NEED_ANY = 0 ;

const integer MIT_NEED_ALL = 1 ;

const integer MIT_KEYS_NUMERIC = 0 ;

const integer MIT_KEYS_ASSOC = 2 ;

/* Methods */

public __construct ([ int $flags = MultipleIterator::MIT_NEED_ALL|MultipleIterator::MIT_KEYS_NUMERIC ] )

public void attachIterator ( Iterator $iterator [, string $infos ] )

public void containsIterator ( Iterator $iterator )

public void countIterators ( void )

public array current ( void )

public void detachIterator ( Iterator $iterator )

public void getFlags ( void )

public array key ( void )

public void next ( void )

public void rewind ( void )

public void setFlags ( int $flags )

public void valid ( void )

}

Predefined Constants

MultipleIterator::MIT_NEED_ANY: Do not require all sub iterators to be valid in iteration.
MultipleIterator::MIT_NEED_ALL: Require all sub iterators to be valid in iteration.
MultipleIterator::MIT_KEYS_NUMERIC: Keys are created from the sub iterators position.
MultipleIterator::MIT_KEYS_ASSOC: Keys are created from sub iterators associated information.

MultipleIterator::attachIterator — Attaches iterator information
MultipleIterator::__construct — Constructs a new MultipleIterator
MultipleIterator::containsIterator — Checks if an iterator is attached
MultipleIterator::countIterators — Gets the number of attached iterator instances
MultipleIterator::current — Gets the registered iterator instances
MultipleIterator::detachIterator — Detaches an iterator
MultipleIterator::getFlags — Gets the flag information
MultipleIterator::key — Gets the registered iterator instances
MultipleIterator::next — Moves all attached iterator instances forward
MultipleIterator::rewind — Rewinds all attached iterator instances
MultipleIterator::setFlags — Sets flags
MultipleIterator::valid — Checks the validity of sub iterators

Коментарии

Apr 15

Автор: sven at rtbg dot de


This iterator has a misleading name and description - it actually acts as a parallel iterator: You attach one or more iterators with a key, integer or NULL, and when you iterate over the MultipleIterator, as the result for current() you get ALL results from all attached iterators as an array (under the key or integer you attached it with), and the same is true for the key() call.



valid() will be valid if any or all iterators are valid, depending on the setting of the $flags - with ANY, you can iterate over a set of iterators with some of them ending before others, and get NULL results from these iterators until the last iterator is at it's end. With ALL, iteration stops when the first iterator stops delivering results.



next() and rewind() will be called on all attached iterators in every case.



<?php



$it1 = new ArrayIterator(array(1,2,3));

$it2 = new ArrayIterator(array(4,5,6));



$multipleIterator = new MultipleIterator(MultipleIterator::MIT_NEED_ALL|MultipleIterator::MIT_KEYS_ASSOC);



$multipleIterator->attachIterator($it1, 1);

$multipleIterator->attachIterator($it2, 'second');



foreach ($multipleIterator as $key => $value) {

    echo "Key\n"; var_dump($key);

    echo "Value\n"; var_dump($value);

    echo "---next---\n";

}

?>



Result with PHP 5.5.0 and up:



Key

array(2) {

  [1]=>

  int(0)

  ["second"]=>

  int(0)

}

Value

array(2) {

  [1]=>

  int(1)

  ["second"]=>

  int(4)

}

---next---

Key

array(2) {

  [1]=>

  int(1)

  ["second"]=>

  int(1)

}

Value

array(2) {

  [1]=>

  int(2)

  ["second"]=>

  int(5)

}

---next---

Key

array(2) {

  [1]=>

  int(2)

  ["second"]=>

  int(2)

}

Value

array(2) {

  [1]=>

  int(3)

  ["second"]=>

  int(6)

}

---next---



Note that PHP 5.4 and 5.3 do not support accessing the key() values in foreach loops because they expect them to not be an array - doing so will cause "Warning: Illegal type returned from MultipleIterator::key()" and the result of (int)0 as the key for all iterations.



Without the MultipleIterator::MIT_KEYS_ASSOC flag, the MultipleIterator will create numeric indices based on the order of attachment.