Flarum mentions

flarum_mention.php

<?php

include '/s9e/TextFormatter/src/autoloader.php';
$configurator = new s9e\TextFormatter\Configurator;

$tagName = 'MENTION';
$tag = $configurator->tags->add($tagName);
$tag->attributes->add('username');
$tag->attributes->add('id')->filterChain->append('#uint');
$tag->filterChain->prepend('mentionator::addId')->addParameterByName('mentionator');
$tag->template = '<a href="{$PROFILE_URL}{@id}"><xsl:value-of select="@username"/></a>';

$configurator->Preg->match('/@(?<username>\\w+)/', $tagName);

class mentionator
{
	protected $cache = ['Bob' => 123];
	public static function addId($tag, self $mentionator)
	{
		$tag->setAttribute('id', $mentionator->getId($tag->getAttribute('username')));

		return true;
	}
	protected function getId($username)
	{
		return (isset($this->cache[$username])) ? $this->cache[$username] : false;
	}
}

extract($configurator->finalize());

$mentionator = new mentionator;
$parser->registeredVars['mentionator'] = $mentionator;

$renderer->setParameter('PROFILE_URL', 'http://example.org/profile/');

$text = '@Bob @NotBob';
$xml  = $parser->parse($text);
$html = $renderer->render($xml);

echo $xml, "\n", $html, "\n";

output.html

<a href="http://example.org/profile/123">Bob</a> @NotBob

output.xml

<r><MENTION id="123" username="Bob">@Bob</MENTION> @NotBob</r>