drupal/core/vendor/symfony/css-selector

CssSelector Component

CssSelector converts CSS selectors to XPath expressions.

The component only goal is to convert CSS selectors to their XPath equivalents:

use Symfony\Component\CssSelector\CssSelector;

print CssSelector::toXPath('div.item > h4 > a');

HTML and XML are different

The CssSelector component comes with an HTML extension which is enabled by default. If you need to use this component with XML documents, you have to disable this HTML extension. That's because, HTML tag & attribute names are always lower-cased, but case-sensitive in XML:

// disable `HTML` extension:
CssSelector::disableHtmlExtension();

// re-enable `HTML` extension:
CssSelector::enableHtmlExtension();

When the HTML extension is enabled, tag names are lower-cased, attribute names are lower-cased, the following extra pseudo-classes are supported: checked, link, disabled, enabled, selected, invalid, hover, visited, and the lang() function is also added.

Resources

This component is a port of the Python cssselect library v0.7.1, which is distributed under the BSD license.

You can run the unit tests with the following command:

$ cd path/to/Symfony/Component/CssSelector/
$ composer install
$ phpunit