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Customization

This is the documentation for the unsupported version 0.19. Please consider upgrading your code to the latest stable version

Document Processing

The best way to manipulate the Abstract Syntax Tree is by implementing a custom Document Processor. These are executed once all other processing is done and the document is ready to be rendered. Simply create a class which implements the DocumentProcessorInterface which contains a single method:

/**
 * @param Document $document
 *
 * @return void
 */
public function processDocument(Document $document);

This method receives the root Document node which you could then walk across, modifying nodes as needed.

Here’s an example of a Document Processor which adds an external-link class to external URLs.

class ExternalLinkProcessor implements DocumentProcessorInterface, ConfigurationAwareInterface
{
    private $config;

    /**
     * @param Configuration $configuration
     */
    public function setConfiguration(Configuration $configuration)
    {
        $this->config = $configuration;
    }

    /**
     * @param Document $document
     *
     * @return void
     */
    public function processDocument(Document $document)
    {
        $walker = $document->walker();
        while ($event = $walker->next()) {
            $node = $event->getNode();

            // Only stop at Link nodes when we first encounter them
            if (!($node instanceof Link) || !$event->isEntering()) {
                continue;
            }

            $url = $node->getUrl();
            if ($this->isUrlExternal($url)) {
                $node->data['attributes']['class'] = 'external-link';
            }
        }
    }

    /**
     * @param string $url
     *
     * @return bool
     */
    private function isUrlExternal($url)
    {
        // Only look at http and https URLs
        if (!preg_match('/^https?:\/\//', $url)) {
            return false;
        }

        $host = parse_url($url, PHP_URL_HOST);

        return $host != $this->config->getConfig('host');
    }
}

And here’s how you’d use it:

$env = Environment::createCommonMarkEnvironment();
$env->addDocumentProcessor(new ExternalLinkProcessor());

$converter = new CommonMarkConverter(['host' => 'commonmark.thephpleague.com'], $env);

$input = 'My two favorite sites are <https://google.com> and <https://commonmark.thephpleague.com>';

echo $converter->convertToHtml($input);

Output (formatted for readability):

<p>
    My two favorite sites are
    <a class="external-link" href="https://google.com">https://google.com</a>
    and
    <a href="https://commonmark.thephpleague.com">https://commonmark.thephpleague.com</a>
</p>

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