Stdlib: DOMXPath — XPath queries on DOMDocument missing (ext/dom/xpath.c)

[PurHur]

Category

stdlib

Problem

DOMDocument / DOMElement tree APIs are tracked in #3326, but XPath evaluation via DOMXPath is a separate php-src surface. Code using $xpath = new DOMXPath($doc); $xpath->query('//item') fails here because class_exists('DOMXPath', false) is false (verified 2026-06-05).

php-src reference

• php/php-src ext/dom/xpath.c — DOMXPath class, query, evaluate, registerNamespace
• php/php-src ext/dom/dom_ce.h — DOM class registry
• php/php-src ext/dom/php_dom.stub.php — DOMXPath stubs

Repro (failure today)

Save as test/repro-maintainer/parity_domxpath.php:

<?php
$xml = '<root><item id="1">a</item><item id="2">b</item></root>';
$doc = new DOMDocument();
$doc->loadXML($xml);
var_export(class_exists('DOMXPath', false));
echo "\n";
$xpath = new DOMXPath($doc);
$nodes = $xpath->query('//item[@id="2"]');
echo $nodes->length, "\n";
echo $nodes->item(0)->textContent, "\n";

./script/docker-exec.sh -- bash -lc 'source script/php-env.sh
php test/repro-maintainer/parity_domxpath.php
php bin/vm.php test/repro-maintainer/parity_domxpath.php
'

Runtime	Expected	Actual (2026-06-05)
Zend PHP	true, 1, b	—
bin/vm.php	same	fails earlier if DOMDocument missing (#3326); otherwise DOMXPath not found

Note: If #3326 is not landed, repro may fail on DOMDocument first — implement XPath after minimal DOM tree exists, or stub DOM in repro for isolated XPath unit tests.

Scope (PHP-in-PHP first)

Path	Work
ext/dom/ (with #3326)	DOMXPath class + query() / evaluate() VM builtins
lib/VM/BuiltinClasses.php	register DOMXPath
libxml2	thin C ABI for xpath context if no PHP binding exists
Tests	test/compliance/cases/stdlib/dom_xpath_query.phpt

Depends on #3326 for DOMDocument / DOMNodeList objects.

Done when

• Repro prints true, 1, b on VM (with DOM tree from Stdlib: ext/dom — DOMDocument/DOMElement XML tree API (ext/dom parity) #3326 or minimal fixture)
• DOMXPath::query() returns DOMNodeList with correct length and node text
• registerNamespace() prefix binding works for namespaced documents (v1 subset OK)
• ./script/ci-fast.sh --filter dom_xpath green

Verification

./script/docker-exec.sh -- bash -lc 'source script/php-env.sh && vendor/bin/phpunit --filter dom_xpath'

Links

• DOM tree umbrella: Stdlib: ext/dom — DOMDocument/DOMElement XML tree API (ext/dom parity) #3326
• North star: Epic: Self-host critical path — compiler compiles itself (M3→M5) #1492

[PurHur]

claim: PHP Compiler STD Lib Advanced — batch (issues #6066, DOM extension)

[PurHur]

Merged via #17525.

Verification:

./script/docker-exec.sh -- bash -lc 'source script/php-env.sh && php bin/vm.php test/repro-maintainer/parity_domxpath.php'
# ok

./script/docker-exec.sh -- bash -lc 'source script/php-env.sh && vendor/bin/phpunit --filter dom_xpath_query'
# OK (3 tests)

DOMXPath is now registered with query() / evaluate() / registerNamespace() backed by VmDomXPath.php (PHP-in-PHP tree walker). Initial scope: //tag, //tag[@attr="val"], /path/segments, child axis, and basic count()/string()/boolean() evaluate forms.