The MultipleIterator class

    (PHP 5 >= 5.3.0, PHP 7, PHP 8)

    Introduction

    An Iterator that sequentially iterates over all attached iterators

    Class synopsis

    class MultipleIterator implements Iterator {
    /* Constants */
    public const int MIT_NEED_ANY;
    public const int MIT_NEED_ALL;
    public const int MIT_KEYS_NUMERIC;
    public const int MIT_KEYS_ASSOC;
    /* Methods */
    public __construct(int $flags = MultipleIterator::MIT_NEED_ALL | MultipleIterator::MIT_KEYS_NUMERIC)
    public attachIterator(Iterator $iterator, string|int|null $info = null): void
    public containsIterator(Iterator $iterator): bool
    public countIterators(): int
    public current(): array
    public detachIterator(Iterator $iterator): void
    public getFlags(): int
    public key(): array
    public next(): void
    public rewind(): void
    public setFlags(int $flags): void
    public valid(): bool
    }

    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.

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    User Contributed Notes 1 note

    up
    37
    sven at rtbg dot de
    9 years ago
    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.
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