Laravel helper function that turn hashtags in a string into links..

hashTagToLink.php

<?php

if (! function_exists('hashTagToLink')) 
{
	function hashTagToLink($string)
	{
		$hashTagMap = [
			'book' => 'books',
		];
		$hashTags = [];

		preg_match_all('/#(\w+)/', $string, $hashTags);

		$processedHashTags = [];

		foreach ($hashTags[1] as $hashTag) {
			if (! in_array($hashTag, $processedHashTags)) {
				if (! empty($hashTagMap[$hashTag])) {
					$hashTagLink = $hashTagMap[$hashTag];
				} else {
					$hashTagLink = $hashTag;
				}
				$string = str_replace('#' . $hashTag, '<a href="' . route('project', $hashTagLink) . '">#' . $hashTag . '</a>', $string);
				$processedHashTags[] = $hashTag;
			}
		}

		return $string;
    }
}