Doubly nested parentheses in a selector throw "Recursion error detected" (e.g. li:not(:not(:nth-child(1)))) #120

Description of the bug

A selector whose parentheses nest two levels deep fails to parse, throwing a QueryPath\Exception from the CSS scanner instead of matching:

QueryPath\Exception: Recursion error detected at iteration 31.

Thrown from QueryPath\CSS\Scanner::nextToken() (src/CSS/Scanner.php), which raises it when the input stream is exhausted while $this->recurse is set.

It is not specific to :has(): any functional pseudo-class nested inside another one with its own parenthesised argument triggers it. One level of nesting, or two levels where the inner pseudo-class takes no argument, is fine.

Both selector engines are affected (find() and remove() throw the same exception), which points at the shared scanner/parser rather than either engine.

Minimal reproducible PHP+HTML snippet to replicate bug

<?php
require __DIR__ . '/vendor/autoload.php';

$xml = '<?xml version="1.0"?><root><ul><li/><li/></ul></root>';

qp($xml)->find('li:not(:not(:nth-child(1)))');
// QueryPath\Exception: Recursion error detected at iteration 29.

QueryPath version

main at 95dbf53. Found while working on #84 / #119.

PHP Version and environment

PHP 8.5 CLI (macOS). Not version-specific as far as tested.

Related

:has() in the DOMTraverser engine also never matches, independently of this; see #121.