comparison vendor/symfony/dom-crawler/Crawler.php @ 0:c75dbcec494b

Initial commit from drush-created site

+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <[e-mail]>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Symfony\Component\DomCrawler;
+
+use Symfony\Component\CssSelector\CssSelectorConverter;
+
+/**
+ * Crawler eases navigation of a list of \DOMNode objects.
+ *
+ * @author Fabien Potencier <[e-mail]>
+ */
+class Crawler implements \Countable, \IteratorAggregate
+{
+    protected $uri;
+
+    /**
+     * @var string The default namespace prefix to be used with XPath and CSS expressions
+     */
+    private $defaultNamespacePrefix = 'default';
+
+    /**
+     * @var array A map of manually registered namespaces
+     */
+    private $namespaces = array();
+
+    /**
+     * @var string The base href value
+     */
+    private $baseHref;
+
+    /**
+     * @var \DOMDocument|null
+     */
+    private $document;
+
+    /**
+     * @var \DOMElement[]
+     */
+    private $nodes = array();
+
+    /**
+     * Whether the Crawler contains HTML or XML content (used when converting CSS to XPath).
+     *
+     * @var bool
+     */
+    private $isHtml = true;
+
+    /**
+     * @param mixed  $node     A Node to use as the base for the crawling
+     * @param string $uri      The current URI
+     * @param string $baseHref The base href value
+     */
+    public function __construct($node = null, $uri = null, $baseHref = null)
+    {
+        $this->uri = $uri;
+        $this->baseHref = $baseHref ?: $uri;
+
+        $this->add($node);
+    }
+
+    /**
+     * Returns the current URI.
+     *
+     * @return string
+     */
+    public function getUri()
+    {
+        return $this->uri;
+    }
+
+    /**
+     * Returns base href.
+     *
+     * @return string
+     */
+    public function getBaseHref()
+    {
+        return $this->baseHref;
+    }
+
+    /**
+     * Removes all the nodes.
+     */
+    public function clear()
+    {
+        $this->nodes = array();
+        $this->document = null;
+    }
+
+    /**
+     * Adds a node to the current list of nodes.
+     *
+     * This method uses the appropriate specialized add*() method based
+     * on the type of the argument.
+     *
+     * @param \DOMNodeList|\DOMNode|array|string|null $node A node
+     *
+     * @throws \InvalidArgumentException when node is not the expected type
+     */
+    public function add($node)
+    {
+        if ($node instanceof \DOMNodeList) {
+            $this->addNodeList($node);
+        } elseif ($node instanceof \DOMNode) {
+            $this->addNode($node);
+        } elseif (is_array($node)) {
+            $this->addNodes($node);
+        } elseif (is_string($node)) {
+            $this->addContent($node);
+        } elseif (null !== $node) {
+            throw new \InvalidArgumentException(sprintf('Expecting a DOMNodeList or DOMNode instance, an array, a string, or null, but got "%s".', is_object($node) ? get_class($node) : gettype($node)));
+        }
+    }
+
+    /**
+     * Adds HTML/XML content.
+     *
+     * If the charset is not set via the content type, it is assumed to be UTF-8,
+     * or ISO-8859-1 as a fallback, which is the default charset defined by the
+     * HTTP 1.1 specification.
+     *
+     * @param string      $content A string to parse as HTML/XML
+     * @param null|string $type    The content type of the string
+     */
+    public function addContent($content, $type = null)
+    {
+        if (empty($type)) {
+            $type = 0 === strpos($content, '<?xml') ? 'application/xml' : 'text/html';
+        }
+
+        // DOM only for HTML/XML content
+        if (!preg_match('/(x|ht)ml/i', $type, $xmlMatches)) {
+            return;
+        }
+
+        $charset = null;
+        if (false !== $pos = stripos($type, 'charset=')) {
+            $charset = substr($type, $pos + 8);
+            if (false !== $pos = strpos($charset, ';')) {
+                $charset = substr($charset, 0, $pos);
+            }
+        }
+
+        // http://www.w3.org/TR/encoding/#encodings
+        // http://www.w3.org/TR/REC-xml/#NT-EncName
+        if (null === $charset &&
+            preg_match('/\<meta[^\>]+charset *= *["\']?([a-zA-Z\-0-9_:.]+)/i', $content, $matches)) {
+            $charset = $matches[1];
+        }
+
+        if (null === $charset) {
+            $charset = preg_match('//u', $content) ? 'UTF-8' : 'ISO-8859-1';
+        }
+
+        if ('x' === $xmlMatches[1]) {
+            $this->addXmlContent($content, $charset);
+        } else {
+            $this->addHtmlContent($content, $charset);
+        }
+    }
+
+    /**
+     * Adds an HTML content to the list of nodes.
+     *
+     * The libxml errors are disabled when the content is parsed.
+     *
+     * If you want to get parsing errors, be sure to enable
+     * internal errors via libxml_use_internal_errors(true)
+     * and then, get the errors via libxml_get_errors(). Be
+     * sure to clear errors with libxml_clear_errors() afterward.
+     *
+     * @param string $content The HTML content
+     * @param string $charset The charset
+     */
+    public function addHtmlContent($content, $charset = 'UTF-8')
+    {
+        $internalErrors = libxml_use_internal_errors(true);
+        $disableEntities = libxml_disable_entity_loader(true);
+
+        $dom = new \DOMDocument('1.0', $charset);
+        $dom->validateOnParse = true;
+
+        set_error_handler(function () { throw new \Exception(); });
+
+        try {
+            // Convert charset to HTML-entities to work around bugs in DOMDocument::loadHTML()
+            $content = mb_convert_encoding($content, 'HTML-ENTITIES', $charset);
+        } catch (\Exception $e) {
+        }
+
+        restore_error_handler();
+
+        if ('' !== trim($content)) {
+            @$dom->loadHTML($content);
+        }
+
+        libxml_use_internal_errors($internalErrors);
+        libxml_disable_entity_loader($disableEntities);
+
+        $this->addDocument($dom);
+
+        $base = $this->filterRelativeXPath('descendant-or-self::base')->extract(array('href'));
+
+        $baseHref = current($base);
+        if (count($base) && !empty($baseHref)) {
+            if ($this->baseHref) {
+                $linkNode = $dom->createElement('a');
+                $linkNode->setAttribute('href', $baseHref);
+                $link = new Link($linkNode, $this->baseHref);
+                $this->baseHref = $link->getUri();
+            } else {
+                $this->baseHref = $baseHref;
+            }
+        }
+    }
+
+    /**
+     * Adds an XML content to the list of nodes.
+     *
+     * The libxml errors are disabled when the content is parsed.
+     *
+     * If you want to get parsing errors, be sure to enable
+     * internal errors via libxml_use_internal_errors(true)
+     * and then, get the errors via libxml_get_errors(). Be
+     * sure to clear errors with libxml_clear_errors() afterward.
+     *
+     * @param string $content The XML content
+     * @param string $charset The charset
+     * @param int    $options Bitwise OR of the libxml option constants
+     *                        LIBXML_PARSEHUGE is dangerous, see
+     *                        http://symfony.com/blog/security-release-symfony-2-0-17-released
+     */
+    public function addXmlContent($content, $charset = 'UTF-8', $options = LIBXML_NONET)
+    {
+        // remove the default namespace if it's the only namespace to make XPath expressions simpler
+        if (!preg_match('/xmlns:/', $content)) {
+            $content = str_replace('xmlns', 'ns', $content);
+        }
+
+        $internalErrors = libxml_use_internal_errors(true);
+        $disableEntities = libxml_disable_entity_loader(true);
+
+        $dom = new \DOMDocument('1.0', $charset);
+        $dom->validateOnParse = true;
+
+        if ('' !== trim($content)) {
+            @$dom->loadXML($content, $options);
+        }
+
+        libxml_use_internal_errors($internalErrors);
+        libxml_disable_entity_loader($disableEntities);
+
+        $this->addDocument($dom);
+
+        $this->isHtml = false;
+    }
+
+    /**
+     * Adds a \DOMDocument to the list of nodes.
+     *
+     * @param \DOMDocument $dom A \DOMDocument instance
+     */
+    public function addDocument(\DOMDocument $dom)
+    {
+        if ($dom->documentElement) {
+            $this->addNode($dom->documentElement);
+        }
+    }
+
+    /**
+     * Adds a \DOMNodeList to the list of nodes.
+     *
+     * @param \DOMNodeList $nodes A \DOMNodeList instance
+     */
+    public function addNodeList(\DOMNodeList $nodes)
+    {
+        foreach ($nodes as $node) {
+            if ($node instanceof \DOMNode) {
+                $this->addNode($node);
+            }
+        }
+    }
+
+    /**
+     * Adds an array of \DOMNode instances to the list of nodes.
+     *
+     * @param \DOMNode[] $nodes An array of \DOMNode instances
+     */
+    public function addNodes(array $nodes)
+    {
+        foreach ($nodes as $node) {
+            $this->add($node);
+        }
+    }
+
+    /**
+     * Adds a \DOMNode instance to the list of nodes.
+     *
+     * @param \DOMNode $node A \DOMNode instance
+     */
+    public function addNode(\DOMNode $node)
+    {
+        if ($node instanceof \DOMDocument) {
+            $node = $node->documentElement;
+        }
+
+        if (null !== $this->document && $this->document !== $node->ownerDocument) {
+            throw new \InvalidArgumentException('Attaching DOM nodes from multiple documents in the same crawler is forbidden.');
+        }
+
+        if (null === $this->document) {
+            $this->document = $node->ownerDocument;
+        }
+
+        // Don't add duplicate nodes in the Crawler
+        if (in_array($node, $this->nodes, true)) {
+            return;
+        }
+
+        $this->nodes[] = $node;
+    }
+
+    /**
+     * Returns a node given its position in the node list.
+     *
+     * @param int $position The position
+     *
+     * @return self
+     */
+    public function eq($position)
+    {
+        if (isset($this->nodes[$position])) {
+            return $this->createSubCrawler($this->nodes[$position]);
+        }
+
+        return $this->createSubCrawler(null);
+    }
+
+    /**
+     * Calls an anonymous function on each node of the list.
+     *
+     * The anonymous function receives the position and the node wrapped
+     * in a Crawler instance as arguments.
+     *
+     * Example:
+     *
+     *     $crawler->filter('h1')->each(function ($node, $i) {
+     *         return $node->text();
+     *     });
+     *
+     * @param \Closure $closure An anonymous function
+     *
+     * @return array An array of values returned by the anonymous function
+     */
+    public function each(\Closure $closure)
+    {
+        $data = array();
+        foreach ($this->nodes as $i => $node) {
+            $data[] = $closure($this->createSubCrawler($node), $i);
+        }
+
+        return $data;
+    }
+
+    /**
+     * Slices the list of nodes by $offset and $length.
+     *
+     * @param int $offset
+     * @param int $length
+     *
+     * @return self
+     */
+    public function slice($offset = 0, $length = null)
+    {
+        return $this->createSubCrawler(array_slice($this->nodes, $offset, $length));
+    }
+
+    /**
+     * Reduces the list of nodes by calling an anonymous function.
+     *
+     * To remove a node from the list, the anonymous function must return false.
+     *
+     * @param \Closure $closure An anonymous function
+     *
+     * @return self
+     */
+    public function reduce(\Closure $closure)
+    {
+        $nodes = array();
+        foreach ($this->nodes as $i => $node) {
+            if (false !== $closure($this->createSubCrawler($node), $i)) {
+                $nodes[] = $node;
+            }
+        }
+
+        return $this->createSubCrawler($nodes);
+    }
+
+    /**
+     * Returns the first node of the current selection.
+     *
+     * @return self
+     */
+    public function first()
+    {
+        return $this->eq(0);
+    }
+
+    /**
+     * Returns the last node of the current selection.
+     *
+     * @return self
+     */
+    public function last()
+    {
+        return $this->eq(count($this->nodes) - 1);
+    }
+
+    /**
+     * Returns the siblings nodes of the current selection.
+     *
+     * @return self
+     *
+     * @throws \InvalidArgumentException When current node is empty
+     */
+    public function siblings()
+    {
+        if (!$this->nodes) {
+            throw new \InvalidArgumentException('The current node list is empty.');
+        }
+
+        return $this->createSubCrawler($this->sibling($this->getNode(0)->parentNode->firstChild));
+    }
+
+    /**
+     * Returns the next siblings nodes of the current selection.
+     *
+     * @return self
+     *
+     * @throws \InvalidArgumentException When current node is empty
+     */
+    public function nextAll()
+    {
+        if (!$this->nodes) {
+            throw new \InvalidArgumentException('The current node list is empty.');
+        }
+
+        return $this->createSubCrawler($this->sibling($this->getNode(0)));
+    }
+
+    /**
+     * Returns the previous sibling nodes of the current selection.
+     *
+     * @return self
+     *
+     * @throws \InvalidArgumentException
+     */
+    public function previousAll()
+    {
+        if (!$this->nodes) {
+            throw new \InvalidArgumentException('The current node list is empty.');
+        }
+
+        return $this->createSubCrawler($this->sibling($this->getNode(0), 'previousSibling'));
+    }
+
+    /**
+     * Returns the parents nodes of the current selection.
+     *
+     * @return self
+     *
+     * @throws \InvalidArgumentException When current node is empty
+     */
+    public function parents()
+    {
+        if (!$this->nodes) {
+            throw new \InvalidArgumentException('The current node list is empty.');
+        }
+
+        $node = $this->getNode(0);
+        $nodes = array();
+
+        while ($node = $node->parentNode) {
+            if (XML_ELEMENT_NODE === $node->nodeType) {
+                $nodes[] = $node;
+            }
+        }
+
+        return $this->createSubCrawler($nodes);
+    }
+
+    /**
+     * Returns the children nodes of the current selection.
+     *
+     * @return self
+     *
+     * @throws \InvalidArgumentException When current node is empty
+     */
+    public function children()
+    {
+        if (!$this->nodes) {
+            throw new \InvalidArgumentException('The current node list is empty.');
+        }
+
+        $node = $this->getNode(0)->firstChild;
+
+        return $this->createSubCrawler($node ? $this->sibling($node) : array());
+    }
+
+    /**
+     * Returns the attribute value of the first node of the list.
+     *
+     * @param string $attribute The attribute name
+     *
+     * @return string|null The attribute value or null if the attribute does not exist
+     *
+     * @throws \InvalidArgumentException When current node is empty
+     */
+    public function attr($attribute)
+    {
+        if (!$this->nodes) {
+            throw new \InvalidArgumentException('The current node list is empty.');
+        }
+
+        $node = $this->getNode(0);
+
+        return $node->hasAttribute($attribute) ? $node->getAttribute($attribute) : null;
+    }
+
+    /**
+     * Returns the node name of the first node of the list.
+     *
+     * @return string The node name
+     *
+     * @throws \InvalidArgumentException When current node is empty
+     */
+    public function nodeName()
+    {
+        if (!$this->nodes) {
+            throw new \InvalidArgumentException('The current node list is empty.');
+        }
+
+        return $this->getNode(0)->nodeName;
+    }
+
+    /**
+     * Returns the node value of the first node of the list.
+     *
+     * @return string The node value
+     *
+     * @throws \InvalidArgumentException When current node is empty
+     */
+    public function text()
+    {
+        if (!$this->nodes) {
+            throw new \InvalidArgumentException('The current node list is empty.');
+        }
+
+        return $this->getNode(0)->nodeValue;
+    }
+
+    /**
+     * Returns the first node of the list as HTML.
+     *
+     * @return string The node html
+     *
+     * @throws \InvalidArgumentException When current node is empty
+     */
+    public function html()
+    {
+        if (!$this->nodes) {
+            throw new \InvalidArgumentException('The current node list is empty.');
+        }
+
+        $html = '';
+        foreach ($this->getNode(0)->childNodes as $child) {
+            $html .= $child->ownerDocument->saveHTML($child);
+        }
+
+        return $html;
+    }
+
+    /**
+     * Evaluates an XPath expression.
+     *
+     * Since an XPath expression might evaluate to either a simple type or a \DOMNodeList,
+     * this method will return either an array of simple types or a new Crawler instance.
+     *
+     * @param string $xpath An XPath expression
+     *
+     * @return array|Crawler An array of evaluation results or a new Crawler instance
+     */
+    public function evaluate($xpath)
+    {
+        if (null === $this->document) {
+            throw new \LogicException('Cannot evaluate the expression on an uninitialized crawler.');
+        }
+
+        $data = array();
+        $domxpath = $this->createDOMXPath($this->document, $this->findNamespacePrefixes($xpath));
+
+        foreach ($this->nodes as $node) {
+            $data[] = $domxpath->evaluate($xpath, $node);
+        }
+
+        if (isset($data[0]) && $data[0] instanceof \DOMNodeList) {
+            return $this->createSubCrawler($data);
+        }
+
+        return $data;
+    }
+
+    /**
+     * Extracts information from the list of nodes.
+     *
+     * You can extract attributes or/and the node value (_text).
+     *
+     * Example:
+     *
+     * $crawler->filter('h1 a')->extract(array('_text', 'href'));
+     *
+     * @param array $attributes An array of attributes
+     *
+     * @return array An array of extracted values
+     */
+    public function extract($attributes)
+    {
+        $attributes = (array) $attributes;
+        $count = count($attributes);
+
+        $data = array();
+        foreach ($this->nodes as $node) {
+            $elements = array();
+            foreach ($attributes as $attribute) {
+                if ('_text' === $attribute) {
+                    $elements[] = $node->nodeValue;
+                } else {
+                    $elements[] = $node->getAttribute($attribute);
+                }
+            }
+
+            $data[] = 1 === $count ? $elements[0] : $elements;
+        }
+
+        return $data;
+    }
+
+    /**
+     * Filters the list of nodes with an XPath expression.
+     *
+     * The XPath expression is evaluated in the context of the crawler, which
+     * is considered as a fake parent of the elements inside it.
+     * This means that a child selector "div" or "./div" will match only
+     * the div elements of the current crawler, not their children.
+     *
+     * @param string $xpath An XPath expression
+     *
+     * @return self
+     */
+    public function filterXPath($xpath)
+    {
+        $xpath = $this->relativize($xpath);
+
+        // If we dropped all expressions in the XPath while preparing it, there would be no match
+        if ('' === $xpath) {
+            return $this->createSubCrawler(null);
+        }
+
+        return $this->filterRelativeXPath($xpath);
+    }
+
+    /**
+     * Filters the list of nodes with a CSS selector.
+     *
+     * This method only works if you have installed the CssSelector Symfony Component.
+     *
+     * @param string $selector A CSS selector
+     *
+     * @return self
+     *
+     * @throws \RuntimeException if the CssSelector Component is not available
+     */
+    public function filter($selector)
+    {
+        if (!class_exists(CssSelectorConverter::class)) {
+            throw new \RuntimeException('To filter with a CSS selector, install the CssSelector component ("composer require symfony/css-selector"). Or use filterXpath instead.');
+        }
+
+        $converter = new CssSelectorConverter($this->isHtml);
+
+        // The CssSelector already prefixes the selector with descendant-or-self::
+        return $this->filterRelativeXPath($converter->toXPath($selector));
+    }
+
+    /**
+     * Selects links by name or alt value for clickable images.
+     *
+     * @param string $value The link text
+     *
+     * @return self
+     */
+    public function selectLink($value)
+    {
+        $xpath = sprintf('descendant-or-self::a[contains(concat(\' \', normalize-space(string(.)), \' \'), %s) ', static::xpathLiteral(' '.$value.' ')).
+                            sprintf('or ./img[contains(concat(\' \', normalize-space(string(@alt)), \' \'), %s)]]', static::xpathLiteral(' '.$value.' '));
+
+        return $this->filterRelativeXPath($xpath);
+    }
+
+    /**
+     * Selects images by alt value.
+     *
+     * @param string $value The image alt
+     *
+     * @return self A new instance of Crawler with the filtered list of nodes
+     */
+    public function selectImage($value)
+    {
+        $xpath = sprintf('descendant-or-self::img[contains(normalize-space(string(@alt)), %s)]', static::xpathLiteral($value));
+
+        return $this->filterRelativeXPath($xpath);
+    }
+
+    /**
+     * Selects a button by name or alt value for images.
+     *
+     * @param string $value The button text
+     *
+     * @return self
+     */
+    public function selectButton($value)
+    {
+        $translate = 'translate(@type, "ABCDEFGHIJKLMNOPQRSTUVWXYZ", "abcdefghijklmnopqrstuvwxyz")';
+        $xpath = sprintf('descendant-or-self::input[((contains(%s, "submit") or contains(%1$s, "button")) and contains(concat(\' \', normalize-space(string(@value)), \' \'), %s)) ', $translate, static::xpathLiteral(' '.$value.' ')).
+                         sprintf('or (contains(%s, "image") and contains(concat(\' \', normalize-space(string(@alt)), \' \'), %s)) or @id=%s or @name=%s] ', $translate, static::xpathLiteral(' '.$value.' '), static::xpathLiteral($value), static::xpathLiteral($value)).
+                         sprintf('| descendant-or-self::button[contains(concat(\' \', normalize-space(string(.)), \' \'), %s) or @id=%s or @name=%s]', static::xpathLiteral(' '.$value.' '), static::xpathLiteral($value), static::xpathLiteral($value));
+
+        return $this->filterRelativeXPath($xpath);
+    }
+
+    /**
+     * Returns a Link object for the first node in the list.
+     *
+     * @param string $method The method for the link (get by default)
+     *
+     * @return Link A Link instance
+     *
+     * @throws \InvalidArgumentException If the current node list is empty or the selected node is not instance of DOMElement
+     */
+    public function link($method = 'get')
+    {
+        if (!$this->nodes) {
+            throw new \InvalidArgumentException('The current node list is empty.');
+        }
+
+        $node = $this->getNode(0);
+
+        if (!$node instanceof \DOMElement) {
+            throw new \InvalidArgumentException(sprintf('The selected node should be instance of DOMElement, got "%s".', get_class($node)));
+        }
+
+        return new Link($node, $this->baseHref, $method);
+    }
+
+    /**
+     * Returns an array of Link objects for the nodes in the list.
+     *
+     * @return Link[] An array of Link instances
+     *
+     * @throws \InvalidArgumentException If the current node list contains non-DOMElement instances
+     */
+    public function links()
+    {
+        $links = array();
+        foreach ($this->nodes as $node) {
+            if (!$node instanceof \DOMElement) {
+                throw new \InvalidArgumentException(sprintf('The current node list should contain only DOMElement instances, "%s" found.', get_class($node)));
+            }
+
+            $links[] = new Link($node, $this->baseHref, 'get');
+        }
+
+        return $links;
+    }
+
+    /**
+     * Returns an Image object for the first node in the list.
+     *
+     * @return Image An Image instance
+     *
+     * @throws \InvalidArgumentException If the current node list is empty
+     */
+    public function image()
+    {
+        if (!count($this)) {
+            throw new \InvalidArgumentException('The current node list is empty.');
+        }
+
+        $node = $this->getNode(0);
+
+        if (!$node instanceof \DOMElement) {
+            throw new \InvalidArgumentException(sprintf('The selected node should be instance of DOMElement, got "%s".', get_class($node)));
+        }
+
+        return new Image($node, $this->baseHref);
+    }
+
+    /**
+     * Returns an array of Image objects for the nodes in the list.
+     *
+     * @return Image[] An array of Image instances
+     */
+    public function images()
+    {
+        $images = array();
+        foreach ($this as $node) {
+            if (!$node instanceof \DOMElement) {
+                throw new \InvalidArgumentException(sprintf('The current node list should contain only DOMElement instances, "%s" found.', get_class($node)));
+            }
+
+            $images[] = new Image($node, $this->baseHref);
+        }
+
+        return $images;
+    }
+
+    /**
+     * Returns a Form object for the first node in the list.
+     *
+     * @param array  $values An array of values for the form fields
+     * @param string $method The method for the form
+     *
+     * @return Form A Form instance
+     *
+     * @throws \InvalidArgumentException If the current node list is empty or the selected node is not instance of DOMElement
+     */
+    public function form(array $values = null, $method = null)
+    {
+        if (!$this->nodes) {
+            throw new \InvalidArgumentException('The current node list is empty.');
+        }
+
+        $node = $this->getNode(0);
+
+        if (!$node instanceof \DOMElement) {
+            throw new \InvalidArgumentException(sprintf('The selected node should be instance of DOMElement, got "%s".', get_class($node)));
+        }
+
+        $form = new Form($node, $this->uri, $method, $this->baseHref);
+
+        if (null !== $values) {
+            $form->setValues($values);
+        }
+
+        return $form;
+    }
+
+    /**
+     * Overloads a default namespace prefix to be used with XPath and CSS expressions.
+     *
+     * @param string $prefix
+     */
+    public function setDefaultNamespacePrefix($prefix)
+    {
+        $this->defaultNamespacePrefix = $prefix;
+    }
+
+    /**
+     * @param string $prefix
+     * @param string $namespace
+     */
+    public function registerNamespace($prefix, $namespace)
+    {
+        $this->namespaces[$prefix] = $namespace;
+    }
+
+    /**
+     * Converts string for XPath expressions.
+     *
+     * Escaped characters are: quotes (") and apostrophe (').
+     *
+     *  Examples:
+     *  <code>
+     *     echo Crawler::xpathLiteral('foo " bar');
+     *     //prints 'foo " bar'
+     *
+     *     echo Crawler::xpathLiteral("foo ' bar");
+     *     //prints "foo ' bar"
+     *
+     *     echo Crawler::xpathLiteral('a\'b"c');
+     *     //prints concat('a', "'", 'b"c')
+     *  </code>
+     *
+     * @param string $s String to be escaped
+     *
+     * @return string Converted string
+     */
+    public static function xpathLiteral($s)
+    {
+        if (false === strpos($s, "'")) {
+            return sprintf("'%s'", $s);
+        }
+
+        if (false === strpos($s, '"')) {
+            return sprintf('"%s"', $s);
+        }
+
+        $string = $s;
+        $parts = array();
+        while (true) {
+            if (false !== $pos = strpos($string, "'")) {
+                $parts[] = sprintf("'%s'", substr($string, 0, $pos));
+                $parts[] = "\"'\"";
+                $string = substr($string, $pos + 1);
+            } else {
+                $parts[] = "'$string'";
+                break;
+            }
+        }
+
+        return sprintf('concat(%s)', implode(', ', $parts));
+    }
+
+    /**
+     * Filters the list of nodes with an XPath expression.
+     *
+     * The XPath expression should already be processed to apply it in the context of each node.
+     *
+     * @param string $xpath
+     *
+     * @return self
+     */
+    private function filterRelativeXPath($xpath)
+    {
+        $prefixes = $this->findNamespacePrefixes($xpath);
+
+        $crawler = $this->createSubCrawler(null);
+
+        foreach ($this->nodes as $node) {
+            $domxpath = $this->createDOMXPath($node->ownerDocument, $prefixes);
+            $crawler->add($domxpath->query($xpath, $node));
+        }
+
+        return $crawler;
+    }
+
+    /**
+     * Make the XPath relative to the current context.
+     *
+     * The returned XPath will match elements matching the XPath inside the current crawler
+     * when running in the context of a node of the crawler.
+     *
+     * @param string $xpath
+     *
+     * @return string
+     */
+    private function relativize($xpath)
+    {
+        $expressions = array();
+
+        // An expression which will never match to replace expressions which cannot match in the crawler
+        // We cannot simply drop
+        $nonMatchingExpression = 'a[name() = "b"]';
+
+        $xpathLen = strlen($xpath);
+        $openedBrackets = 0;
+        $startPosition = strspn($xpath, " \t\n\r\0\x0B");
+
+        for ($i = $startPosition; $i <= $xpathLen; ++$i) {
+            $i += strcspn($xpath, '"\'[]|', $i);
+
+            if ($i < $xpathLen) {
+                switch ($xpath[$i]) {
+                    case '"':
+                    case "'":
+                        if (false === $i = strpos($xpath, $xpath[$i], $i + 1)) {
+                            return $xpath; // The XPath expression is invalid
+                        }
+                        continue 2;
+                    case '[':
+                        ++$openedBrackets;
+                        continue 2;
+                    case ']':
+                        --$openedBrackets;
+                        continue 2;
+                }
+            }
+            if ($openedBrackets) {
+                continue;
+            }
+
+            if ($startPosition < $xpathLen && '(' === $xpath[$startPosition]) {
+                // If the union is inside some braces, we need to preserve the opening braces and apply
+                // the change only inside it.
+                $j = 1 + strspn($xpath, "( \t\n\r\0\x0B", $startPosition + 1);
+                $parenthesis = substr($xpath, $startPosition, $j);
+                $startPosition += $j;
+            } else {
+                $parenthesis = '';
+            }
+            $expression = rtrim(substr($xpath, $startPosition, $i - $startPosition));
+
+            if (0 === strpos($expression, 'self::*/')) {
+                $expression = './'.substr($expression, 8);
+            }
+
+            // add prefix before absolute element selector
+            if ('' === $expression) {
+                $expression = $nonMatchingExpression;
+            } elseif (0 === strpos($expression, '//')) {
+                $expression = 'descendant-or-self::'.substr($expression, 2);
+            } elseif (0 === strpos($expression, './/')) {
+                $expression = 'descendant-or-self::'.substr($expression, 3);
+            } elseif (0 === strpos($expression, './')) {
+                $expression = 'self::'.substr($expression, 2);
+            } elseif (0 === strpos($expression, 'child::')) {
+                $expression = 'self::'.substr($expression, 7);
+            } elseif ('/' === $expression[0] || '.' === $expression[0] || 0 === strpos($expression, 'self::')) {
+                $expression = $nonMatchingExpression;
+            } elseif (0 === strpos($expression, 'descendant::')) {
+                $expression = 'descendant-or-self::'.substr($expression, 12);
+            } elseif (preg_match('/^(ancestor|ancestor-or-self|attribute|following|following-sibling|namespace|parent|preceding|preceding-sibling)::/', $expression)) {
+                // the fake root has no parent, preceding or following nodes and also no attributes (even no namespace attributes)
+                $expression = $nonMatchingExpression;
+            } elseif (0 !== strpos($expression, 'descendant-or-self::')) {
+                $expression = 'self::'.$expression;
+            }
+            $expressions[] = $parenthesis.$expression;
+
+            if ($i === $xpathLen) {
+                return implode(' | ', $expressions);
+            }
+
+            $i += strspn($xpath, " \t\n\r\0\x0B", $i + 1);
+            $startPosition = $i + 1;
+        }
+
+        return $xpath; // The XPath expression is invalid
+    }
+
+    /**
+     * @param int $position
+     *
+     * @return \DOMElement|null
+     */
+    public function getNode($position)
+    {
+        if (isset($this->nodes[$position])) {
+            return $this->nodes[$position];
+        }
+    }
+
+    /**
+     * @return int
+     */
+    public function count()
+    {
+        return count($this->nodes);
+    }
+
+    /**
+     * @return \ArrayIterator|\DOMElement[]
+     */
+    public function getIterator()
+    {
+        return new \ArrayIterator($this->nodes);
+    }
+
+    /**
+     * @param \DOMElement $node
+     * @param string      $siblingDir
+     *
+     * @return array
+     */
+    protected function sibling($node, $siblingDir = 'nextSibling')
+    {
+        $nodes = array();
+
+        do {
+            if ($node !== $this->getNode(0) && 1 === $node->nodeType) {
+                $nodes[] = $node;
+            }
+        } while ($node = $node->$siblingDir);
+
+        return $nodes;
+    }
+
+    /**
+     * @param \DOMDocument $document
+     * @param array        $prefixes
+     *
+     * @return \DOMXPath
+     *
+     * @throws \InvalidArgumentException
+     */
+    private function createDOMXPath(\DOMDocument $document, array $prefixes = array())
+    {
+        $domxpath = new \DOMXPath($document);
+
+        foreach ($prefixes as $prefix) {
+            $namespace = $this->discoverNamespace($domxpath, $prefix);
+            if (null !== $namespace) {
+                $domxpath->registerNamespace($prefix, $namespace);
+            }
+        }
+
+        return $domxpath;
+    }
+
+    /**
+     * @param \DOMXPath $domxpath
+     * @param string    $prefix
+     *
+     * @return string
+     *
+     * @throws \InvalidArgumentException
+     */
+    private function discoverNamespace(\DOMXPath $domxpath, $prefix)
+    {
+        if (isset($this->namespaces[$prefix])) {
+            return $this->namespaces[$prefix];
+        }
+
+        // ask for one namespace, otherwise we'd get a collection with an item for each node
+        $namespaces = $domxpath->query(sprintf('(//namespace::*[name()="%s"])[last()]', $this->defaultNamespacePrefix === $prefix ? '' : $prefix));
+
+        if ($node = $namespaces->item(0)) {
+            return $node->nodeValue;
+        }
+    }
+
+    /**
+     * @param string $xpath
+     *
+     * @return array
+     */
+    private function findNamespacePrefixes($xpath)
+    {
+        if (preg_match_all('/(?P<prefix>[a-z_][a-z_0-9\-\.]*+):[^"\/:]/i', $xpath, $matches)) {
+            return array_unique($matches['prefix']);
+        }
+
+        return array();
+    }
+
+    /**
+     * Creates a crawler for some subnodes.
+     *
+     * @param \DOMElement|\DOMElement[]|\DOMNodeList|null $nodes
+     *
+     * @return static
+     */
+    private function createSubCrawler($nodes)
+    {
+        $crawler = new static($nodes, $this->uri, $this->baseHref);
+        $crawler->isHtml = $this->isHtml;
+        $crawler->document = $this->document;
+        $crawler->namespaces = $this->namespaces;
+
+        return $crawler;
+    }
+}