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    <h3>Editing: NodeExtension.php</h3>
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/*
 * This file is part of the Symfony package.
 *
 * (c) Fabien Potencier &lt;fabien@symfony.com&gt;
 *
 * 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\Node;
use Symfony\Component\CssSelector\XPath\Translator;
use Symfony\Component\CssSelector\XPath\XPathExpr;

/**
 * XPath expression translator node 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 &lt;jeanfrancois.simon@sensiolabs.com&gt;
 *
 * @internal
 */
class NodeExtension extends AbstractExtension
{
    public const ELEMENT_NAME_IN_LOWER_CASE = 1;
    public const ATTRIBUTE_NAME_IN_LOWER_CASE = 2;
    public const ATTRIBUTE_VALUE_IN_LOWER_CASE = 4;

    private $flags;

    public function __construct(int $flags = 0)
    {
        $this-&gt;flags = $flags;
    }

    /**
     * @return $this
     */
    public function setFlag(int $flag, bool $on): self
    {
        if ($on &amp;&amp; !$this-&gt;hasFlag($flag)) {
            $this-&gt;flags += $flag;
        }

        if (!$on &amp;&amp; $this-&gt;hasFlag($flag)) {
            $this-&gt;flags -= $flag;
        }

        return $this;
    }

    public function hasFlag(int $flag): bool
    {
        return (bool) ($this-&gt;flags &amp; $flag);
    }

    /**
     * {@inheritdoc}
     */
    public function getNodeTranslators(): array
    {
        return [
            'Selector' =&gt; [$this, 'translateSelector'],
            'CombinedSelector' =&gt; [$this, 'translateCombinedSelector'],
            'Negation' =&gt; [$this, 'translateNegation'],
            'Function' =&gt; [$this, 'translateFunction'],
            'Pseudo' =&gt; [$this, 'translatePseudo'],
            'Attribute' =&gt; [$this, 'translateAttribute'],
            'Class' =&gt; [$this, 'translateClass'],
            'Hash' =&gt; [$this, 'translateHash'],
            'Element' =&gt; [$this, 'translateElement'],
        ];
    }

    public function translateSelector(Node\SelectorNode $node, Translator $translator): XPathExpr
    {
        return $translator-&gt;nodeToXPath($node-&gt;getTree());
    }

    public function translateCombinedSelector(Node\CombinedSelectorNode $node, Translator $translator): XPathExpr
    {
        return $translator-&gt;addCombination($node-&gt;getCombinator(), $node-&gt;getSelector(), $node-&gt;getSubSelector());
    }

    public function translateNegation(Node\NegationNode $node, Translator $translator): XPathExpr
    {
        $xpath = $translator-&gt;nodeToXPath($node-&gt;getSelector());
        $subXpath = $translator-&gt;nodeToXPath($node-&gt;getSubSelector());
        $subXpath-&gt;addNameTest();

        if ($subXpath-&gt;getCondition()) {
            return $xpath-&gt;addCondition(sprintf('not(%s)', $subXpath-&gt;getCondition()));
        }

        return $xpath-&gt;addCondition('0');
    }

    public function translateFunction(Node\FunctionNode $node, Translator $translator): XPathExpr
    {
        $xpath = $translator-&gt;nodeToXPath($node-&gt;getSelector());

        return $translator-&gt;addFunction($xpath, $node);
    }

    public function translatePseudo(Node\PseudoNode $node, Translator $translator): XPathExpr
    {
        $xpath = $translator-&gt;nodeToXPath($node-&gt;getSelector());

        return $translator-&gt;addPseudoClass($xpath, $node-&gt;getIdentifier());
    }

    public function translateAttribute(Node\AttributeNode $node, Translator $translator): XPathExpr
    {
        $name = $node-&gt;getAttribute();
        $safe = $this-&gt;isSafeName($name);

        if ($this-&gt;hasFlag(self::ATTRIBUTE_NAME_IN_LOWER_CASE)) {
            $name = strtolower($name);
        }

        if ($node-&gt;getNamespace()) {
            $name = sprintf('%s:%s', $node-&gt;getNamespace(), $name);
            $safe = $safe &amp;&amp; $this-&gt;isSafeName($node-&gt;getNamespace());
        }

        $attribute = $safe ? '@'.$name : sprintf('attribute::*[name() = %s]', Translator::getXpathLiteral($name));
        $value = $node-&gt;getValue();
        $xpath = $translator-&gt;nodeToXPath($node-&gt;getSelector());

        if ($this-&gt;hasFlag(self::ATTRIBUTE_VALUE_IN_LOWER_CASE)) {
            $value = strtolower($value);
        }

        return $translator-&gt;addAttributeMatching($xpath, $node-&gt;getOperator(), $attribute, $value);
    }

    public function translateClass(Node\ClassNode $node, Translator $translator): XPathExpr
    {
        $xpath = $translator-&gt;nodeToXPath($node-&gt;getSelector());

        return $translator-&gt;addAttributeMatching($xpath, '~=', '@class', $node-&gt;getName());
    }

    public function translateHash(Node\HashNode $node, Translator $translator): XPathExpr
    {
        $xpath = $translator-&gt;nodeToXPath($node-&gt;getSelector());

        return $translator-&gt;addAttributeMatching($xpath, '=', '@id', $node-&gt;getId());
    }

    public function translateElement(Node\ElementNode $node): XPathExpr
    {
        $element = $node-&gt;getElement();

        if ($element &amp;&amp; $this-&gt;hasFlag(self::ELEMENT_NAME_IN_LOWER_CASE)) {
            $element = strtolower($element);
        }

        if ($element) {
            $safe = $this-&gt;isSafeName($element);
        } else {
            $element = '*';
            $safe = true;
        }

        if ($node-&gt;getNamespace()) {
            $element = sprintf('%s:%s', $node-&gt;getNamespace(), $element);
            $safe = $safe &amp;&amp; $this-&gt;isSafeName($node-&gt;getNamespace());
        }

        $xpath = new XPathExpr('', $element);

        if (!$safe) {
            $xpath-&gt;addNameTest();
        }

        return $xpath;
    }

    /**
     * {@inheritdoc}
     */
    public function getName(): string
    {
        return 'node';
    }

    private function isSafeName(string $name): bool
    {
        return 0 &lt; preg_match('~^[a-zA-Z_][a-zA-Z0-9_.-]*$~', $name);
    }
}
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