--- /dev/null
+<?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\XPath\XPathExpr;
+
+/**
+ * XPath expression translator pseudo-class 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 PseudoClassExtension extends AbstractExtension
+{
+ /**
+ * {@inheritdoc}
+ */
+ public function getPseudoClassTranslators()
+ {
+ return array(
+ 'root' => array($this, 'translateRoot'),
+ 'first-child' => array($this, 'translateFirstChild'),
+ 'last-child' => array($this, 'translateLastChild'),
+ 'first-of-type' => array($this, 'translateFirstOfType'),
+ 'last-of-type' => array($this, 'translateLastOfType'),
+ 'only-child' => array($this, 'translateOnlyChild'),
+ 'only-of-type' => array($this, 'translateOnlyOfType'),
+ 'empty' => array($this, 'translateEmpty'),
+ );
+ }
+
+ /**
+ * @param XPathExpr $xpath
+ *
+ * @return XPathExpr
+ */
+ public function translateRoot(XPathExpr $xpath)
+ {
+ return $xpath->addCondition('not(parent::*)');
+ }
+
+ /**
+ * @param XPathExpr $xpath
+ *
+ * @return XPathExpr
+ */
+ public function translateFirstChild(XPathExpr $xpath)
+ {
+ return $xpath
+ ->addStarPrefix()
+ ->addNameTest()
+ ->addCondition('position() = 1');
+ }
+
+ /**
+ * @param XPathExpr $xpath
+ *
+ * @return XPathExpr
+ */
+ public function translateLastChild(XPathExpr $xpath)
+ {
+ return $xpath
+ ->addStarPrefix()
+ ->addNameTest()
+ ->addCondition('position() = last()');
+ }
+
+ /**
+ * @param XPathExpr $xpath
+ *
+ * @return XPathExpr
+ *
+ * @throws ExpressionErrorException
+ */
+ public function translateFirstOfType(XPathExpr $xpath)
+ {
+ if ('*' === $xpath->getElement()) {
+ throw new ExpressionErrorException('"*:first-of-type" is not implemented.');
+ }
+
+ return $xpath
+ ->addStarPrefix()
+ ->addCondition('position() = 1');
+ }
+
+ /**
+ * @param XPathExpr $xpath
+ *
+ * @return XPathExpr
+ *
+ * @throws ExpressionErrorException
+ */
+ public function translateLastOfType(XPathExpr $xpath)
+ {
+ if ('*' === $xpath->getElement()) {
+ throw new ExpressionErrorException('"*:last-of-type" is not implemented.');
+ }
+
+ return $xpath
+ ->addStarPrefix()
+ ->addCondition('position() = last()');
+ }
+
+ /**
+ * @param XPathExpr $xpath
+ *
+ * @return XPathExpr
+ */
+ public function translateOnlyChild(XPathExpr $xpath)
+ {
+ return $xpath
+ ->addStarPrefix()
+ ->addNameTest()
+ ->addCondition('last() = 1');
+ }
+
+ /**
+ * @param XPathExpr $xpath
+ *
+ * @return XPathExpr
+ *
+ * @throws ExpressionErrorException
+ */
+ public function translateOnlyOfType(XPathExpr $xpath)
+ {
+ if ('*' === $xpath->getElement()) {
+ throw new ExpressionErrorException('"*:only-of-type" is not implemented.');
+ }
+
+ return $xpath->addCondition('last() = 1');
+ }
+
+ /**
+ * @param XPathExpr $xpath
+ *
+ * @return XPathExpr
+ */
+ public function translateEmpty(XPathExpr $xpath)
+ {
+ return $xpath->addCondition('not(*) and not(string-length())');
+ }
+
+ /**
+ * {@inheritdoc}
+ */
+ public function getName()
+ {
+ return 'pseudo-class';
+ }
+}