Competitive Research Category
March 27, 2024
<?php
/*
* This file is part of the Symfony package.
*
* (c) Fabien Potencier <fabien@symfony.com>
*
* For the full copyright and license information, please view the LICENSE
* file that was distributed with this source code.
*/
namespace Symfony\Component\CssSelector\XPath\Extension;
use Symfony\Component\CssSelector\Exception\ExpressionErrorException;
use Symfony\Component\CssSelector\Exception\SyntaxErrorException;
use Symfony\Component\CssSelector\Node\FunctionNode;
use Symfony\Component\CssSelector\Parser\Parser;
use Symfony\Component\CssSelector\XPath\Translator;
use Symfony\Component\CssSelector\XPath\XPathExpr;
/**
* XPath expression translator function extension.
*
* This component is a port of the Python cssselect library,
* which is copyright Ian Bicking, @see https://github.com/SimonSapin/cssselect.
*
* @author Jean-François Simon <jeanfrancois.simon@sensiolabs.com>
*
* @internal
*/
class FunctionExtension extends AbstractExtension
{
/**
* {@inheritdoc}
*/
public function getFunctionTranslators(): array
{
return [
'nth-child' => [$this, 'translateNthChild'],
'nth-last-child' => [$this, 'translateNthLastChild'],
'nth-of-type' => [$this, 'translateNthOfType'],
'nth-last-of-type' => [$this, 'translateNthLastOfType'],
'contains' => [$this, 'translateContains'],
'lang' => [$this, 'translateLang'],
];
}
/**
* @throws ExpressionErrorException
*/
public function translateNthChild(XPathExpr $xpath, FunctionNode $function, bool $last = false, bool $addNameTest = true): XPathExpr
{
try {
[$a, $b] = Parser::parseSeries($function->getArguments());
} catch (SyntaxErrorException $e) {
throw new ExpressionErrorException(sprintf('Invalid series: "%s".', implode('", "', $function->getArguments())), 0, $e);
}
$xpath->addStarPrefix();
if ($addNameTest) {
$xpath->addNameTest();
}
if (0 === $a) {
return $xpath->addCondition('position() = '.($last ? 'last() - '.($b - 1) : $b));
}
if ($a < 0) {
if ($b < 1) {
return $xpath->addCondition('false()');
}
$sign = '<=';
} else {
$sign = '>=';
}
$expr = 'position()';
if ($last) {
$expr = 'last() - '.$expr;
--$b;
}
if (0 !== $b) {
$expr .= ' - '.$b;
}
$conditions = [sprintf('%s %s 0', $expr, $sign)];
if (1 !== $a && -1 !== $a) {
$conditions[] = sprintf('(%s) mod %d = 0', $expr, $a);
}
return $xpath->addCondition(implode(' and ', $conditions));
// todo: handle an+b, odd, even
// an+b means every-a, plus b, e.g., 2n+1 means odd
// 0n+b means b
// n+0 means a=1, i.e., all elements
// an means every a elements, i.e., 2n means even
// -n means -1n
// -1n+6 means elements 6 and previous
}
public function translateNthLastChild(XPathExpr $xpath, FunctionNode $function): XPathExpr
{
return $this->translateNthChild($xpath, $function, true);
}
public function translateNthOfType(XPathExpr $xpath, FunctionNode $function): XPathExpr
{
return $this->translateNthChild($xpath, $function, false, false);
}
/**
* @throws ExpressionErrorException
*/
public function translateNthLastOfType(XPathExpr $xpath, FunctionNode $function): XPathExpr
{
if ('*' === $xpath->getElement()) {
throw new ExpressionErrorException('"*:nth-of-type()" is not implemented.');
}
return $this->translateNthChild($xpath, $function, true, false);
}
/**
* @throws ExpressionErrorException
*/
public function translateContains(XPathExpr $xpath, FunctionNode $function): XPathExpr
{
$arguments = $function->getArguments();
foreach ($arguments as $token) {
if (!($token->isString() || $token->isIdentifier())) {
throw new ExpressionErrorException('Expected a single string or identifier for :contains(), got '.implode(', ', $arguments));
}
}
return $xpath->addCondition(sprintf(
'contains(string(.), %s)',
Translator::getXpathLiteral($arguments[0]->getValue())
));
}
/**
* @throws ExpressionErrorException
*/
public function translateLang(XPathExpr $xpath, FunctionNode $function): XPathExpr
{
$arguments = $function->getArguments();
foreach ($arguments as $token) {
if (!($token->isString() || $token->isIdentifier())) {
throw new ExpressionErrorException('Expected a single string or identifier for :lang(), got '.implode(', ', $arguments));
}
}
return $xpath->addCondition(sprintf(
'lang(%s)',
Translator::getXpathLiteral($arguments[0]->getValue())
));
}
/**
* {@inheritdoc}
*/
public function getName(): string
{
return 'function';
}
}