Stdlib: MultipleIterator — parallel Traversable iteration (ext/spl/spl_iterators.c) #6792

Category

stdlib

Problem

MultipleIterator (iterate several Traversable objects in lockstep) is missing. class_exists('MultipleIterator') is false on VM. SPL umbrella #4546 lists wrapper iterators broadly; this ticket scopes the multi-attach iterator used in zip-style foreach over parallel streams.

php-src reference

• php/php-src ext/spl/spl_iterators.c — spl_multipleiterator_*, attach/detach, MIT_NEED_ALL / MIT_NEED_ANY flags
• php/php-src ext/spl/spl_iterators.stub.php

Repro (failure today)

./script/docker-exec.sh -- bash -lc 'source script/php-env.sh && php bin/vm.php -r "
var_dump(class_exists(\"MultipleIterator\"));
"'

Observed (2026-06-06): bool(false).

Minimal usage (Zend):

<?php
$m = new MultipleIterator(MultipleIterator::MIT_NEED_ALL);
$m->attachIterator(new ArrayIterator([1, 2]));
$m->attachIterator(new ArrayIterator(['a', 'b']));
foreach ($m as $row) { var_dump($row); }
// array(2) { [0]=> int(1) [1]=> string(1) "a" } …

Scope (this repo)

PHP-in-PHP first: implement attach/detach/valid/current/next in ext/spl/; no new C runtime.

Done when

• class_exists('MultipleIterator') is true.
• Constants MultipleIterator::MIT_NEED_ALL and MIT_NEED_ANY match Zend values.
• Attach two ArrayIterators; foreach ($m as $row) yields parallel tuples matching php-src.
• test/compliance/cases/stdlib/multiple_iterator.phpt passes on VM.

Verification

./script/docker-exec.sh -- bash -lc 'source script/php-env.sh
vendor/bin/phpunit test/compliance/VMTest.php --filter multiple_iterator
'

Related

• Stdlib: SPL iterator wrappers — FilterIterator, LimitIterator, AppendIterator, … (ext/spl parity) #4546 SPL iterator wrappers umbrella
• Stdlib: SPL core structures — ArrayObject / SplQueue / SplStack / SplObjectStorage (ext/spl parity) #3330 ArrayObject / SplQueue / SplStack
• Stdlib: SPL EmptyIterator / RecursiveArrayIterator / OuterIterator — iterator graph missing (ext/spl/spl_iterators.c) #6593 OuterIterator graph