List most used php functions in a tree of directories with php files

mostUsedPhpFunctions.php

<?php
$baseDir = 'phpfiles/path/';

$dir = new RecursiveDirectoryIterator($baseDir);
$Iterator = new RecursiveIteratorIterator($dir);
$regexFiles = new RegexIterator($Iterator, '/^.+\.php$/i', RecursiveRegexIterator::GET_MATCH);
$phpFunctions = get_defined_functions();
$functionsCount = array();

foreach ($regexFiles as $filename => $file) {
        $tokens = token_get_all('<?php '.file_get_contents($file[0]) . ' ?>');
        $tokens = array_filter($tokens, function($token) use ($phpFunctions) {
            return $token[0] == T_STRING && in_array($token[1], $phpFunctions['internal']);
        });

        foreach ($tokens as $token){
            $functionName = $token[1];
            $functionsCount[$functionName] =
                array_key_exists($functionName, $functionsCount)
                    ? $functionsCount[$functionName]+1
                    : 1;
        }
}
arsort($functionsCount);
print_r($functionsCount);