--- /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\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()
+ {
+ return array(
+ 'nth-child' => array($this, 'translateNthChild'),
+ 'nth-last-child' => array($this, 'translateNthLastChild'),
+ 'nth-of-type' => array($this, 'translateNthOfType'),
+ 'nth-last-of-type' => array($this, 'translateNthLastOfType'),
+ 'contains' => array($this, 'translateContains'),
+ 'lang' => array($this, 'translateLang'),
+ );
+ }
+
+ /**
+ * @param XPathExpr $xpath
+ * @param FunctionNode $function
+ * @param bool $last
+ * @param bool $addNameTest
+ *
+ * @return XPathExpr
+ *
+ * @throws ExpressionErrorException
+ */
+ public function translateNthChild(XPathExpr $xpath, FunctionNode $function, $last = false, $addNameTest = true)
+ {
+ try {
+ list($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 = array(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
+ }
+
+ /**
+ * @param XPathExpr $xpath
+ * @param FunctionNode $function
+ *
+ * @return XPathExpr
+ */
+ public function translateNthLastChild(XPathExpr $xpath, FunctionNode $function)
+ {
+ return $this->translateNthChild($xpath, $function, true);
+ }
+
+ /**
+ * @param XPathExpr $xpath
+ * @param FunctionNode $function
+ *
+ * @return XPathExpr
+ */
+ public function translateNthOfType(XPathExpr $xpath, FunctionNode $function)
+ {
+ return $this->translateNthChild($xpath, $function, false, false);
+ }
+
+ /**
+ * @param XPathExpr $xpath
+ * @param FunctionNode $function
+ *
+ * @return XPathExpr
+ *
+ * @throws ExpressionErrorException
+ */
+ public function translateNthLastOfType(XPathExpr $xpath, FunctionNode $function)
+ {
+ if ('*' === $xpath->getElement()) {
+ throw new ExpressionErrorException('"*:nth-of-type()" is not implemented.');
+ }
+
+ return $this->translateNthChild($xpath, $function, true, false);
+ }
+
+ /**
+ * @param XPathExpr $xpath
+ * @param FunctionNode $function
+ *
+ * @return XPathExpr
+ *
+ * @throws ExpressionErrorException
+ */
+ public function translateContains(XPathExpr $xpath, FunctionNode $function)
+ {
+ $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())
+ ));
+ }
+
+ /**
+ * @param XPathExpr $xpath
+ * @param FunctionNode $function
+ *
+ * @return XPathExpr
+ *
+ * @throws ExpressionErrorException
+ */
+ public function translateLang(XPathExpr $xpath, FunctionNode $function)
+ {
+ $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()
+ {
+ return 'function';
+ }
+}