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php-mf2 is a superb open source PHP microformats2 parser that also supports classic microformats per the microformats2 parsing specification.
php-mf2 has PHP Composer support and that is the recommended way to install and use it.
Just one file
You can also use php-mf2 with the "just use this one file" approach by following the instructions at https://github.com/indieweb/php-mf2#installation
You could install it by just downloading /Mf2/Parser.php and including that